Journal articles: 'PH combination electrode'

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Sharma, Arun Kumar, and A. K. Chopra. "Efficiency of aluminum and iron electrodes in removal of colour, turbidity and total suspended solid from biologically treated municipal wastewater." Journal of Applied and Natural Science 7, no. 2 (December 1, 2015): 799–805. http://dx.doi.org/10.31018/jans.v7i2.686.

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The present investigation was undertaken to observe the effect of different combinations of aluminium and iron (Al-Al, Al-Fe, Fe-Fe and Fe-Al) electrodes on the removal of colour, turbidity (TD) and total suspended solids (TSS) of biologically treated municipal wastewater ( BTMW) using applied potential (V), operating time (OT) and initial pH. The maximum removal of colour (98.7 %) and TSS (96.89 %) was found with the use of Al-Al combination with optimum operating conditions (Voltage: 40 V; OT: 40 mins.; IED: 1.0 cm; EA: 160 cm2; initial pH: 7.5 and ST: 30 mins). It was interesting to note that TD of BTMW was completely removed at these optimal operating conditions. The economic evaluation of electrode combinations was observed to be in the order of Fe-Al (1.17 US $/m3)> Al-Fe (1.11 US $/m3)> Fe-Fe (1.08 US $/m3) >Al-Al (1.01 US $/m3) in terms of energy and electrode consumption. Thus, the BTMW can be effectively treated with the Al-Al electrode combination in comparison to other electrode combinations (Al-Fe , Fe-Fe and Fe-Al).

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Scholz, Fritz, Tim Steinhardt, Heike Kahlert, Jens R. Pörksen, and Jürgen Behnert. "Teaching pH Measurements with a Student-Assembled Combination Quinhydrone Electrode." Journal of Chemical Education 82, no. 5 (May 2005): 782. http://dx.doi.org/10.1021/ed082p782.

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Quigley, M. N., and W. S. Reid. "Comparison of a combination pH electrode and field effect transistor electrode for the determination of soil pH and lime requirement." Communications in Soil Science and Plant Analysis 26, no. 19-20 (November 1995): 3371–83. http://dx.doi.org/10.1080/00103629509369533.

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Sharma, Arun Kumar, and A. K. Chopra. "Influence of operating conditions on the electrolytic treatment for the removal of color, TSS, hardness and alkalinity using Al-Al electrode combination." Journal of Applied and Natural Science 6, no. 1 (June 1, 2014): 279–85. http://dx.doi.org/10.31018/jans.v6i1.415.

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The present investigation observed the effect of current density (CD), operating time (OT), inter electrode distance (IED), electrode area (EA), initial pH and settling time (ST) using Al-Al electrode combination on the removal of color, total suspended solids (TSS), hardness (HR) and alkalinity (ALK) from biologically treated municipal wastewater (BTMW) of Sewage Treatment Plant (STP), Jagjeetpur, Haridwar, India. The maximum removal of color (99.86%), TSS (98.7%), HR (78.9%) and ALK (43.69 %) from BTMW was found with the optimum operating conditions of CD (2.65 A/m2), OT (40 mins.), IED (0.5 cm), EA (160 cm2), initial pH (7.5) and ST (60 min.). However, the maximum removal of ALK was found with the optimum operating conditions of CD (1.68 A/m2), OT (40 mins.), IED (1.0 cm), EA (80 cm2), initial pH (7.5) and ST (90 min.) The electrolytic treatment ( ET) brought down the concentration of HR and ALK to the desirable limit of the BIS standards of drinking water. There was no need of pH adjustment of the BTMW during ET as the optimal removal efficiency was close to the pH of 7.5. Under optimal operating conditions, the operating cost was found to be 1.01 $/m3 in terms of the electrode consumption (23.71x 10-5 kg Al/m3) and energy consumption (101.76 Kwh/m3). The study revealed that BTMW can be effectively treated with the Al-Al electrode combination for color, TSS, HR and ALK removal.

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Esfandyari, Yahya, Keivan Saeb, Ahmad Tavana, Aptin Rahnavard, and Farid Gholamreza Fahimi. "Effective removal of cefazolin from hospital wastewater by the electrocoagulation process." Water Science and Technology 80, no. 12 (December 15, 2019): 2422–29. http://dx.doi.org/10.2166/wst.2020.003.

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Abstract The present study evaluated the treatment of hospital wastewater by the electrocoagulation process using aluminum and iron electrodes. The effects of pH, voltage and reaction time on the removal efficiencies of the antibiotic cefazolin, chemical oxygen demand (COD) and turbidity were investigated. The results showed that by increasing reaction time and input voltage, the removal efficiency of pollutants was increased. The highest removal efficiency of cefazolin, COD, and turbidity occurred at neutral pH, which may have been related to the formation of aluminum hydroxide (Al(OH)3) flocs through the combination of aluminum released from the surface of the electrode and the hydroxide ions present in the solution. The conductivity of the treated wastewater at neutral to alkaline pH decreased compared to acidic pH, which may have been due to the adsorption of anions and cations from the solution by the Al(OH)3 flocs. The electrode and energy consumption in the present study was higher than in other studies, which may have been due to the high concentration of COD in and the turbidity of the solution.

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Persson, A., P. Lingström, T. Bäcklund, and J. W. V. van Dijken. "Evaluation of a skin reference electrode used for intraoral pH measurements in combination with a microtouch electrode." Clinical Oral Investigations 8, no. 3 (February 12, 2004): 172–75. http://dx.doi.org/10.1007/s00784-004-0257-4.

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Gidudu, Brian, and Evans M. Nkhalambayausi Chirwa. "Application of Biosurfactants and Pulsating Electrode Configurations as Potential Enhancers for Electrokinetic Remediation of Petrochemical Contaminated Soil." Sustainability 12, no. 14 (July 13, 2020): 5613. http://dx.doi.org/10.3390/su12145613.

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The remediation of soil contaminated with petrochemicals using conventional methods is very difficult because of the complex emulsions formed by solids, oil, and water. Electrokinetic remediation has of recent shown promising potential in the removal of organics from contaminated media as calls for further improvement of the technology are still made. This work investigated the performance of electrokinetic remediation of soil contaminated with petrochemicals by applying fixed electrode configurations and continuous approaching electrode configurations. This was done in combination with bioremediation by inoculating hydrocarbon degrading bacteria and biosurfactants with the aim of obtaining an improved method of remediation. The results obtained show that the biosurfactant produced by the hydrocarbon degrading bacteria Pseudomonas aeruginosa was able to enhance oil extraction to 74.72 ± 2.87%, 57.375 ± 3.75%, and 46.2 ± 4.39% for 185 mm fixed electrodes, 335-260-185 mm continuous approaching electrodes, and 335 mm fixed electrode configurations, respectively. By maintaining high current flow, the 335-260-185 mm continuous approaching electrodes configuration enhanced electroosmotic flow (EOF) on every event of electrodes movement. The fixed electrode configuration of 185 mm provided amiable pH conditions for bacterial growth by allowing quick neutrality of the pH due to high EOF as compared to the 335 mm fixed electrodes configuration. After 240 h, the carbon content in the soil was reduced from 0.428 ± 0.11 mg of carbon/mg of the soil to 0.103 ± 0.005, 0.11355 ± 0.0006, and 0.1309 ± 0.004 for 185 mm, 335-260-185 mm, and 335 mm, respectively. The application of biosurfactants and continuous approaching electrodes reduced the energy expenditure of electrokinetic remediation by enhancing the decontamination process with respect to time.

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Veeken, A. H. M., and W. H. Rulkens. "Innovative developments in the selective removal and reuse of heavy metals from wastewaters." Water Science and Technology 47, no. 10 (May 1, 2003): 9–16. http://dx.doi.org/10.2166/wst.2003.0525.

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Sulphide precipitation of heavy metal containing wastewaters results in low effluent concentrations. However, sulphide precipitation is not widely applied in practice because the dosing of sulphide cannot adequately be controlled. A new process was developed where the combination of a sulphide-selective electrode (pS-electrode) and pH electrode controls the sulphide addition. Precipitation experiments were performed on a laboratory-scale in batch and continuous reactor systems with synthetic wastewaters containing Cd, Cu, Ni, Pb or Zn. The response of the pS-electrode during precipitation was unique for each heavy metal and was directly related to the solubility product of the corresponding metal sulphide. The metals were removed to levels <0.05 mg.l-1 at pH 6.0 by sulphide precipitation while maintaining a total sulphide concentration <0.02 mg.l-1. By the control of pS at different levels and keeping the pH constant at 6.0, the metals in solutions of both Cu and Zn could be precipitated selectively from solution in a batch and continuous reactors. The use of a membrane reactor in combination with control of pH and pS offers a simple, cheap, efficient and sustainable technique with respect to obtaining very low effluent concentrations and selective removal of metals as pure metal sulphides which can be reused.

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Golan, Rotem, Ittai Gavrieli, Boaz Lazar, and Jiwchar Ganor. "The determination of pH in hypersaline lakes with a conventional combination glass electrode." Limnology and Oceanography: Methods 12, no. 11 (November 2014): 810–15. http://dx.doi.org/10.4319/lom.2014.12.810.

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10

Sharma, Arun Kumar, and A. K. Chopra. "Removal of COD and BOD from biologically treated municipal wastewater by electrochemical treatment." Journal of Applied and Natural Science 5, no. 2 (December 1, 2013): 475–81. http://dx.doi.org/10.31018/jans.v5i2.356.

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The present investigation observed the effect of current density (CD), operating time (OT), inter electrode distance (IED), electrode area (EA), initial pH and settling time (ST) using Fe-Fe electrode combination on the removal of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) from biologically treated municipal wastewater (BTMW) of Sewage Treatment Plant (STP). The maximum removal of COD (92.35%) from BTMW was found with the optimum operating conditions of CD (2.82 A/m2), OT (40 mins.), IED (0.5 cm), EA (160 cm2), initial pH (7.5) and ST (60 min.), while the maximum removal of BOD (84.88%) was found with the ST (30 min.) at the same operating conditions. There was no need of pH adjustment of the BTMW during ET as the optimal removal efficiency was close to the pH of 7.5. Under optimal operating conditions, the operating cost was found to be 54.29 Rs./m3 / 1.08 US$/m3 in terms of the electrode consumption (78.48 x 10-5 kg Al/m3 ) and energy consumption (108.48 Kwh/m3).

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Wahyuningsih, Sayekti, Puji Estiningsih, Velina Anjani, Liya N. M. Z. Saputri, Candra Purnawan, and Edi Pramono. "Enhancing Remazol Yellow FG Decolorination by Adsorption and Photoelectrocatalytic Degradation." Molekul 12, no. 2 (November 30, 2017): 126. http://dx.doi.org/10.20884/1.jm.2017.12.2.321.

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The combination of adsorption and photoelectrocatalytic degradation system for Remazol Yellow FG decolorization has been studied. The adsorption of Remazol Yellow FG was carried out using alumina and silica, which was activated using H2SO4 1 M and NaOH 1 M. The adsorption results at optimum pH were then used for photoelectrocatalytic process. Photoelectrocatalytic degradation cell was built by electrode Ti/TiO2 as a cathode and Ti/TiO2-PbO as an anode. Material characterizations were performed by UV-Vis Spectrophotometers, X-Ray Diffraction (XRD), and Fourier Transform Infra-Red (FTIR). Activation of the adsorbent can increase Remazol Yellow FG adsorption on alumina base and silica acid that were reached 99.500% and 81.631%, respectively. The optimum condition of Remazol Yellow FG 6 adsorption by alumina acid was at pH 3, alumina base were at pH 4 and pH 5, and silica base were at pH 6 and pH 10. Degradation of Remazol Yellow FG using TiO2-PbO electrode was 72.756% at potential cells of 7.5 Volts for 10 minutes. The combination of adsorption and photoelectrocatalytic degradation can decrease the concentration of Remazol Yellow FG achieved 99.705%

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12

Olya, Mohammad Ebrahim, and Azam Pirkarami. "Electrocoagulation for the removal of phenol and aldehyde contaminants from resin effluent." Water Science and Technology 68, no. 9 (October 19, 2013): 1940–49. http://dx.doi.org/10.2166/wst.2013.439.

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This paper is a report on a study which aimed to investigate the effect of different current density, pH, temperature, and cathode–anode combination on the removal of phenol and aldehyde in two samples of actual resin effluent through the process of electrocoagulation using solar energy. Current density 60 A/m2 and pH 6 proved to be the best levels for both contaminants. As for the effect of temperature, although the highest degree of phenol and aldehyde removal was achieved at 15 °C, 25 °C was taken to be the optimum temperature for economic reasons. The Fe-Fe combination of electrodes was found to be the best as it led to nearly 93% of phenol removal and approximately 95% of aldehyde removal. Also, the effect of electrode combination on energy consumption was studied. It was observed that the Fe-Fe combination consumed the least amount of energy (0.7–4.3 kWh/m3 of wastewater in the case of phenol and 0.8–4 kWh/m3 of wastewater in the case aldehyde). Moreover, the Fe-Fe combination brought about the best results in terms of chemical oxygen demand removal: 93% in both cases. Finally, an economic analysis was performed for the electrocoagulation process.

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Gengec, Nevin Atalay, Erhan Gengec, Orhan Taner Can, and Mehmet Kobya. "Electrooxidation of Alkyd Resin Production Wastewater By Boren Doped Diamond Electrode." Academic Perspective Procedia 1, no. 1 (November 9, 2018): 1026–33. http://dx.doi.org/10.33793/acperpro.01.01.168.

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Wastewater of alkyd resin production (ARW) has low pH value (2.3) and high organic matters (15,304 mg/L of TOC and 45,220 mg/L of COD) as well as is toxic and non-biodegradable. In addition to, it does not respond to chemical coagulation and adsorption. Thus, advance oxidation processes (AOPs) or combinations of AOPs are very important alternatives for treatment of ARW due to the advantages which they have. The purpose of this study is to investigate the treatment efficiencies of anodic electrooxidation process by boren doped diamond electrode (BDD). The effect of process parameters such as current density (40-100 mA/cm2), operation time (0-180 min.) and pH of wastewater were investigated. The maximum removal efficiencies were obtained as 42.3 % of TOC and 43.4 % of COD at the 100 mA/cm2, 180 min and pH of 3.5. The consumed electric energy and operation cost were calculated as 169.07 kWh/m3 and 42.27 TL. Although as the removal ratios were not seemed very high, the removed COD and TOC values showed the potential of EO with BDD. Consequently, EO was a suitable process for the treatment of ARW; however the results showed that it must be applied with combination of other AOPs.

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Gutsal, Valery, Sander Sieuwerts, and Rodrigo Bibiloni. "High-throughput pH monitoring method for application in dairy fermentations." Journal of Dairy Research 85, no. 4 (August 22, 2018): 453–59. http://dx.doi.org/10.1017/s0022029918000717.

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Optimization of dairy fermentation processes often requires multiplexed pH measurements over several hours. The method developed here measures up to 90 samples simultaneously, where traditional electrode-based methods require a lot more time for handing the same number of samples. Moreover, the new method employs commonly used materials and can be used with a wider range of fluorescence readers than commercial 96-well plates with optical pH sensors. For this application, a milk-like transparent medium is developed that shows acidification properties with dairy starters that are similar to milk. Combination of this milk-like medium and 3 fluorescent indicators allow precise measurements of pH in a range of 4·0–7·0. The new method showed much higher throughput compared to the benchmark electrode systems while being as accurate, as shown by successful application for a comparison of various dairy starter cultures and for optimizing the inoculation rate.

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Lebon, Emilie, Pierre Fau, Maurice Comtat, Myrtil Kahn, Alix Sournia-Saquet, Pierre Temple-Boyer, Brigitte Dubreuil, Philippe Behra, and Katia Fajerwerg. "In Situ Metalorganic Deposition of Silver Nanoparticles on Gold Substrate and Square Wave Voltammetry: A Highly Efficient Combination for Nanomolar Detection of Nitrate Ions in Sea Water." Chemosensors 6, no. 4 (November 6, 2018): 50. http://dx.doi.org/10.3390/chemosensors6040050.

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The electro-reduction of nitrate ions in artificial sea water was investigated at a gold substrate (EAu) functionalized by silver nanoparticles (AgNPs). These AgNPs were generated in situ on the gold substrate by the direct decomposition of the metalorganic N,N′-diisopropylacetamidinate silver precursor [Ag(Amd)] in the liquid phase. Very small and well dispersed AgNPs were deposited on the gold electrode and then used as working electrode (EAu/AgNPs). Square wave voltammetry (SWV) was successfully employed to detect nitrate ions (NO3−) with a detection limit (LOD) of 0.9 nmol∙L−1 in artificial sea water (pH = 6.0) without pre-concentration or pH adjustment.

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Lin, Cong, Wuxin Li, Cengceng Fang, Qidan Wu, Hucheng Xie, Deliang Xu, and Bizhi Xu. "Formation of the regularly arranged tubular pores during electrophoretic deposition." Materials Science-Poland 35, no. 1 (March 10, 2017): 151–58. http://dx.doi.org/10.1515/msp-2017-0013.

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AbstractThe formation mechanism of regularly arranged tubular pores during an acid-based electrophoretic deposition (EPD) process was explored by studying the influence of gauze electrodes and suspension properties on the pore structures. The gauze electrodes can change the intensity of electrical field on the electrode surface, and thus control the pore locations. The mesh size not only restricts the ultimate pore size, but also determines the regularity of the pores. Under specific experimental conditions, a critical value of mesh size for attaining the regularity of the pores arrangement can be determined. Meanwhile, the pore structures can be controlled by a combination of pH value and zeta potential of the suspensions. The strength of the acidity is also one of the determinants to the final structures.

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JIANG, J., L. ZHU, W. QIAN, H. CHEN, C. FENG, S. HAN, H. LIN, and F. Y. YE. "ELECTROCHEMICAL INVESTIGATION OF DA AND UA ON CARBOXYLATED GRAPHENE OXIDE/LANTHANUM ELECTRODES WITH SUNDRY CONTENT OF CTAB." Surface Review and Letters 24, no. 07 (August 15, 2017): 1750097. http://dx.doi.org/10.1142/s0218625x17500974.

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Glassy carbon electrodes (GCE) were modified by carboxylated graphene oxide/lanthanum with various concentrations of hexadecyl trimethyl ammonium bromide (CTAB), and the treated electrodes, called CTAB/GO-COOLa/GCE, were prepared for the detection of uric acid (UA) and dopamine (DA) by using the differential pulse voltammetry (DPV) and the cyclic voltammetry (CV). The results show that the modified electrode’s electrocatalytic activity could be affected by several factors in the examination, they are the pH value of the system, the main content of CTAB, various concentrations and rates of scan. With a combination of carboxylated graphene oxide/lanthanum and CTAB, the resulted CTAB/GO-COOLa/GCE sensors showed preeminent selectivity and obvious catalytic property toward the electro-oxidation of UA and DA. In optimized conditions, the response of the CTAB/GO-COOLa/GCE electrode for DA was linear in the region of 0.03–500.0[Formula: see text][Formula: see text]M with detection limits of 0.036[Formula: see text][Formula: see text]M [Formula: see text]. Two linear response ranges for the determination UA were obtained from ranges of 1 to 200[Formula: see text][Formula: see text]M and 200 to 1300[Formula: see text][Formula: see text]M with a detection limit of 0.42[Formula: see text][Formula: see text]M [Formula: see text]. Moreover, the refined electrode was used in the inspection of DA and UA in real samples of serum and urine successfully, displaying its potential application of real samples involved in electroanalysis.

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Xu, Zhan Wei, and Gui Lin Zheng. "Implementation of a High-Precision pH Sensor." Applied Mechanics and Materials 373-375 (August 2013): 358–62. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.358.

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A high-precision pH sensor based on electrochemical principle is proposed in the paper. The principle of the sensor, the performance parameters of MCU, hardware architecture and experiment are introduced. The NEC microprocessor, which is low-power and high stability, is adopted as core processor. The three operational amplifiers same-phase parallel amplifying circuit not only matches the impendence of the pH combination electrode, but also eliminates the impact of wire resistance on pH measurement. The system's capacity of resisting disturbance is improved. Using 18-bit AD converter, which has programmable amplifier on chip, improves measurement accuracy. Both theoretical analysis and experimental results show the effectiveness of the pH sensor. A full description of the pH sensor and implementation are presented.

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Brenes, Norma, Michael N. Quigley, and W. Shaw Reid. "Performance characteristics in the determination of soil‐water pH and soil‐SMP buffer pH using a flow‐through junction combination electrode." Communications in Soil Science and Plant Analysis 28, no. 9-10 (May 1997): 759–75. http://dx.doi.org/10.1080/00103629709369828.

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Le, Son Thanh, Khai Cao Le, Linh Tuan Doan, and Anh Thi Doan. "Effect of some effective parameters on COD Removal from Nam Son Landfill Leachate by electrocoagulation." Vietnam Journal of Science and Technology 55, no. 5 (October 20, 2017): 540. http://dx.doi.org/10.15625/2525-2518/55/5/9225.

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Leachate becomes ahead of wastewaters as being the most difficult to treat due to its complex and widely variable composition. In this research, the leachate treatment performance by electrocoagulation (EC) was studied. The samples of leachate were taken from Nam Son landfill in Hanoi. The effects of factors namely current intensity, electrolysis time, initial pH and anode materials on the EC performance were investigated via chemical oxygen demand (COD) removal efficiencies. The input leachate properties were obtained as COD, NH4+ and pH in the range of around 6247 ± 295, 1270 ± 38 mg/l and 8 ± 0.1, respectively. Mono-polar electrocoagulation unit was carried out in a batch system for leachate treatment with iron electrodes and approximately 1.8 litter of leachate. Firstly, with the increase in current (1 to 4A), the COD removal efficiencies increased from 50.00 to 78.57% (pH = 8 and operating time = 40 min). Secondly, by the increase in operating time, the treatment performance also went up significantly in first 40 min, then nearly level-off at above 73 % (pH=8, current intensity = 3A). In addition, the effect of pH in range of 5 to 10 on the electrocoagulation process was studied and showed the highest treatment efficiencies in neutral and mild alkaline medium, especially between 6 < pH < 8. Finally, the electrode materials made of iron and aluminum was investigated and the result indicated that when the iron anodes were replaced by aluminum, the COD removal efficiency experienced a considerable decline, from 70 to 37.93% (pH = 8 and operating time = 40 min). In combination of all experiments, the optimum operating conditions were achieved as iron electrodes, current intensity of 3A, electrolysis time of 40 min, the raw pH with iron electrodes, resulting the maximum COD removal efficiencies of 73.21%. As a result, the electrocoagulation can be applied to leachate pre-treatment.

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Teng, Xiaolei, Junfeng Li, Zhaoyang Wang, Weiwei Liu, Dongbao Song, Zhao Chun, and XiaoYa Deng. "Treatment of Methyl Blue Wastewater by Steel Slag Particle Three-Dimensional Electrode System." Science of Advanced Materials 12, no. 3 (March 1, 2020): 344–49. http://dx.doi.org/10.1166/sam.2020.3544.

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The particle electrode was prepared by using industrial waste slag as raw material, and the surface morphology of the particle electrode was characterized by scanning electron microscopy. The comparison experiments showed that under the same experimental conditions, the efficiency of removing the methyl blue from the three-dimensional electrode of the steel slag particles was 23.48% higher than that of the two-dimensional electrode, and the energy consumption was reduced by 36.2%. The results showed that the primary and secondary factors affecting the methyl blue wastewater of steel slag particles are electrolyte concentration, voltage, initial waste concentration and particle volume. Under the optimal combination of pH 3, voltage 12 V, initial methyl blue concentration of 15 mg/L and electrolyte concentration of 0.3 mol/L, the removal rate of methyl blue reached 91.41%.

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Kettle, A. J., and C. C. Winterbourn. "Influence of superoxide on myeloperoxidase kinetics measured with a hydrogen peroxide electrode." Biochemical Journal 263, no. 3 (November 1, 1989): 823–28. http://dx.doi.org/10.1042/bj2630823.

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Stimulated neutrophils discharge large quantities of superoxide (O2.-), which dismutates to form H2O2. In combination with Cl-, H2O2 is converted into the potent oxidant hypochlorous acid (HOCl) by the haem enzyme myeloperoxidase. We have used an H2O2 electrode to monitor H2O2 uptake by myeloperoxidase, and have shown that in the presence of Cl- this accurately represents production of HOCl. Monochlorodimedon, which is routinely used to assay production of HOCl, inhibited H2O2 uptake by 95%. This result confirms that monochlorodimedon inhibits myeloperoxidase, and that the monochlorodimedon assay grossly underestimates the activity of myeloperoxidase. With 10 microM-H2O2 and 100 mM-Cl-, myeloperoxidase had a neutral pH optimum. Increasing the H2O2 concentration to 100 microM lowered the pH optimum to pH 6.5. Above the pH optimum there was a burst of H2O2 uptake that rapidly declined due to accumulation of Compound II. High concentrations of H2O2 inhibited myeloperoxidase and promoted the formation of Compound II. These effects of H2O2 were decreased at higher concentrations of Cl-. We propose that H2O2 competes with Cl- for Compound I and reduces it to Compound II, thereby inhibiting myeloperoxidase. Above pH 6.5, O2.- generated by xanthine oxidase and acetaldehyde prevented H2O2 from inhibiting myeloperoxidase, increasing the initial rate of H2O2 uptake. O2.- allowed myeloperoxidase to function optimally with 100 microM-H2O2 at pH 7.0. This occurred because, as previously demonstrated, O2.- prevents Compound II from accumulating by reducing it to ferric myeloperoxidase. In contrast, at pH 6.0, where Compound II did not accumulate, O2.- retarded the uptake of H2O2. We propose that by generating O2.- neutrophils prevent H2O2 and other one-electron donors from inhibiting myeloperoxidase, and ensure that this enzyme functions optimally at neutral pH.

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JOHNO, IKUO, KAZUMI KASHIBA, KIKUKO KOMEDA, YOKO TAKEDA, TETSUO MIYATA, KANJI ARIGA, and SHIKIFUMI KITAZAWA. "A Qualitative Identification of Powder Preparations and Granules Using Card Type pH Meter with The Sheet Combination Electrode." Japanese Journal of Hospital Pharmacy 17, no. 1 (1991): 77–82. http://dx.doi.org/10.5649/jjphcs1975.17.77.

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Zhao, Dong Jiao, Fei Yan, Yao Fang Xuan, Xiao Ping Dong, and Feng Na Xi. "Self-Assembled Combination of Graphene with Au Nanoparticle-Doped Copper-Hexacyanoferrate Multilayer for Sensitive Detection of Hydrazine." Advanced Materials Research 586 (November 2012): 18–23. http://dx.doi.org/10.4028/www.scientific.net/amr.586.18.

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Based on self-assembled combination of graphene with Au nanoparticle-doped copper hexacyanoferrate (CuHCF) multilayers, a electrochemical biosensor for sensitive detection of hydrazine has been reported. Graphene was functionalized by wrapping with poly(diallyldimethylammonium chloride) (PDDA). Such polyelectrolyte modified graphene (PDDA-G) was water-soluble and possessed net positive charge. Based on electrostatic self-assembly, graphene multilayers modified electrode (ITO/G-M) was fabricated. After binding with mercaptopropionic acid stabled Au nanoparticles (MPA-AuNPs), three dimensional graphene-AuNPs electrode was obtained. CuHCF multilayers were then formed on AuNPs center by successive self-assembly and solution epitaxy. Due to the synergistic effect of graphene and AuNPs, the developed biosensor (ITO/G-M/CuHCF-M) exhibited fast and sensitive amperometric response for the determination of hydrazine in near physiological pH. The linear response for the determination of hydrazine ranged from 4.0 × 10-7 to 1.3 × 10-4 M with a detection limit of 7.2 × 10-8 M. The biosensor exhibited high reproducibility and stability resulted from simple and reproducible self-assembly methodology.

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Chow, Edith, Devi D. Liana, Burkhard Raguse, and J. Justin Gooding. "A Potentiometric Sensor for pH Monitoring with an Integrated Electrochromic Readout on Paper." Australian Journal of Chemistry 70, no. 9 (2017): 979. http://dx.doi.org/10.1071/ch17191.

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Paper-based potentiometric pH sensors allow multiple measurements to be recorded in a cost-effective manner but usually in combination with an external display unit. In this work, a potentiometric pH sensor is integrated with an electrochromic readout system all on paper. The potentiometric pH sensor is based on electropolymerised aniline on a conductive gold nanoparticle film working electrode. The voltage output of the sensor is amplified using an operational amplifier and generated across an electrochromic readout system. The readout system comprises four segments of electrochromic Prussian blue/polyaniline on conductive gold nanoparticle films connected by graphite resistive separators. The colour of each segment is dependent on the voltage output from the potentiometric sensor and can be used to determine the pH range of a sample or whether the sample pH falls outside a critical value. This type of integrated paper device can be used for multiple measurements and also be applied to the development of other types of potentiometric sensors.

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Frutos-Puerto, Samuel, Conrado Miró, and Eduardo Pinilla-Gil. "Nafion-Protected Sputtered-Bismuth Screen-Printed Electrode for On-site Voltammetric Measurements of Cd(II) and Pb(II) in Natural Water Samples." Sensors 19, no. 2 (January 11, 2019): 279. http://dx.doi.org/10.3390/s19020279.

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In this work, we explore the protection with Nafion of commercial sputtered-bismuth screen-printed electrodes (BiSPSPEs), to improve its ability for on-site determination of Cd(II) and Pb(II) ions in ambient water samples. The modified screen-printed platform was coupled with a miniaturized cell, in combination with a battery-operated stirring system and a portable potentiostat operated by a laptop for decentralized electrochemical measurements using Square-Wave Anodic Stripping Voltammetry (SWASV). We also describe a detailed electrode surface characterization by microscopy and surface analysis techniques, before and after the modification with Nafion, to get insight about modification effect on signal size and stability. Optimization of the chemical composition of the medium including the optimization of pH, and instrumental parameters, resulted in a method with detection limits in the low ng/mL range (3.62 and 3.83 ng·mL−1 for Cd and Pb respectively). Our results show an improvement of the sensitivity and stability for Nafion-protected BiSPSPEs in pH = 4.4 medium, and similar or lower detection limits than comparable methods on commercial BiSPSPEs. The values obtained for Pb(II) and Cd(II) in natural water samples agreed well with those obtained by the much more costly Inductively Coupled Plasma Mass Spectrometry, ICP-MS, technique as a reference method (recoveries from 75% to 111%).

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Bernardo-Arugay, Ivyleen C., and Leslie Joy L. Diaz. "Separating Nanoclay Minerals via Electrophoretic Deposition." Key Engineering Materials 654 (July 2015): 240–44. http://dx.doi.org/10.4028/www.scientific.net/kem.654.240.

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This paper presents the possibility of separating nanoclays from aqueous synthetic slurry of two clays by EPD. Na-Montmorillonite (NM) from Southern Clay Products and kaolinite (K) from Source Clays Repository were used at 2:1 weight ratio at 3.5% solid loading for making the synthetic slurry. Effect of applied potential [2 and 4V] and electrode gaps [1 and 2centimeters] was investigated on the yield and on the NM/K ratio of the deposit. Stainless steel was used for working and counter electrodes. AUTOLAB (pgstat302N) was used in the conduct of EPD. Open circuit potential of the slurries was used as reference potential for EPD. Slurries were stirred at constant rate of 300 rpm during EPD for twenty minutes. Shimadzu XRD-7000 was used to determine NM/K ratio of the dried deposit. ANOVA of two-factor fixed effect Model was employed with F-test at 5% significance level.NM slurries have negative bulk potential [163-170 mV], while positive bulk potential to kaolinite slurries. NM slurries had higher bulk conductivities [1.616 mS/cm] and pH [~10.2] than kaolinite slurries. These distinct slurry properties could lead to their differential electrophoresis during EPD. Effect of the interaction of applied potential and electrode gap for the yield and the NM/K ratio was significant. High potential [4V] - low electrode [1cm] gap had the highest yield of deposit. NM/K ratios of the deposits were compared to the clay ratio of the synthetic slurry. High potential [4V]–high electrode [2cm] gap showed highest NM/K ratio at an average of 5.2 :1 from 2:1. This means Na-MMT has been successfully separated from kaolinite from aqueous synthetic clay slurry by EPD at specific potential – electrode gap combination.

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Wahyuningsih, Sayekti, Velina Anjani, Hanik Munawaroh, and Candra Purnawan. "Optimization of Rhodamine B Decolorization by Adsorption and Photoelectrodegradation Combination System." ALCHEMY Jurnal Penelitian Kimia 14, no. 2 (September 3, 2018): 276. http://dx.doi.org/10.20961/alchemy.14.2.16440.277-290.

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A combination of adsorption and photoelectrodegradation system was performed to reduce the concentration of Rhodamine B dye in water. The adsorption was conducted using silica and alumina activated by acid and base under various predetermined pH of Rhodamine B. The photoelectrodegradation process was performed using Ti/TiO2 electrode as a cathode and Ti/TiO2-NiO as an anode. TiO2 was synthesized from titanium tetra-isopropoxide precursor (TTiP) by sol-gel method. TiO2-NiO composite was synthesized with the same precursor with the addition of Ni(NO3)2.6H2O. The result shows that the activation changes the amount of OH total in the adsorbent. The acid-activated adsorbent showed an optimum adsorption activity when Rhodamine B was in base condition caused by zwitter ionic structure. It reversely occured to base-activated adsorbent where an optimum absorption activity reached at acid condition. The application of base-activated silica in adsorption and photoelectrodegradation combination system decreased the concentration of Rhodamine B dye up to 98.79% using photoanode Ti/TiO2-NiO under pH 2 at bias potential 6 V.

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SINGH, BIJENDRA, and CHHAGAN LAL. "Enhanced Efficiency of Photogalvanic Cell based on Mixed Triphenylmethane Dyes." Asian Journal of Chemistry 32, no. 2 (January 15, 2020): 466–70. http://dx.doi.org/10.14233/ajchem.2020.22547.

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The study focused on the enhancement of solar power generation and storage capacity of a photogalvanic cell ethylene diaminetetraacetic acid as reductant, xylene cyanol FF and patent blue as photosensitizers. This chemical system with changed concentrations, a combination electrode and a very small Pt electrode was used to fabricate a modified photogalvanic cell. The modified cell showed greatly enhanced performance in terms of photopotential (868.0 mV), photocurrent (230.0 μA), efficiency (0.64 %) and the maximum output (power) of the cell was found to be 199.64 W. The photogalvanic cell can be used at this power level for 115 min in the dark due to the storage capacity of the cell. The effects of various parameters such as pH, reductant concentration, dye concentration, diffusion length, light intensity, and electrode area on electrical output of the cell were also investigated. The current-voltage (i-v) characteristics of the cell have been studied and a mechanism for the photocurrent generation in photogalvanic cell has also been proposed.

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Câmpean, Anuţa, Mihaela Tertiş, and Robert Săndulescu. "Voltammetric determination of some alkaloids and other compounds in pharmaceuticals and urine using an electrochemically activated glassy carbon electrode." Open Chemistry 9, no. 4 (August 1, 2011): 688–700. http://dx.doi.org/10.2478/s11532-011-0058-y.

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AbstractElectrochemical behaviour of some alkaloids, namely: caffeine, aminophylline, theophylline, codeine phosphate and papaverine hydrochloride, that are in solution in various combinations or in the presence of other compounds contained in pharmaceuticals or in real samples (urine) was investigated using cyclic voltammetry (CV), square-wave voltammetry (SWV) and differential pulse voltammetry (DPV) on electrochemically activated glassy carbon electrode. The proposed electroanalytical methods were successfully applied in the simultaneous determination of these alkaloids in different combination or in the presence of other compounds. The great part of these combinations can be analyzed simultaneously because they practically do not interfere. The electrochemical test methods attempted to detect the presence of alkaloids in urine samples collected from subjects who consumed coffee (caffeine), and from a patient under treatment with Miofilin® (aminophylline). Urine samples were determined after filtration, without prior dilution and after dilutiion with acetate buffer at pH 4.5. Best results were obtained using DPV performed on electrochemically activated glassy carbon electrode. Thus in samples taken from subjects who drink coffee the caffeine concentration detected was 6.21×10−7 mol L−1 in the first sample and 7.77×10−7 mol L−1 in the second sample, while aminophylline concentration detected was 1.15×10−7 mol L−1.

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Wygant, Michele B., John A. Statler, and Alan Henshall. "Improvements in Amperometric Detection of Sulfite in Food Matrixes." Journal of AOAC INTERNATIONAL 80, no. 6 (November 1, 1997): 1374–80. http://dx.doi.org/10.1093/jaoac/80.6.1374.

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Abstract Sulfite is added to foods as an antimicrobial, antibrowning agent, or antioxidant. It also can occur naturally, and is often used in the production of beer and wine. For years the standard methodology for determination of sulfite in foods has been the Monier–Williams method, which is a combination of acid distillation and titration. Recently, AOAC adopted a chromatographic method based on a method developed by Kim and Kim for the determination of sulfite. The method combines ion exclusion chromatography with direct-current (DC) amperometric detection to provide more convenient and accurate quantitation of sulfite. However, fouling of the platinum working electrode results in a rapid decrease in method sensitivity. As a result, standards must be injected before and after every sample, and the electrode must be polished frequently to maintain adequate detection limits. Pulsed amperometric detection overcomes electrode fouling problems by repeatedly and continuously applying cleaning potentials to the working electrode. Using this technique, a reproducible electrode surface can be maintained, and injection-to-injection repeatability is greatly improved. A comparison of method performance for both DC and pulsed amperometric detection is presented. Also investigated was the stability of sulfite samples at varying pH, and in the presence or absence of a preservative.

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Shibata, Manabu, Makoto Kato, Yasukazu Iwamoto, Satoshi Nomura, and Takashi Kakiuchi. "Potentiometric determination of pH values of dilute sulfuric acid solutions with glass combination electrode equipped with ionic liquid salt bridge." Journal of Electroanalytical Chemistry 705 (September 2013): 81–85. http://dx.doi.org/10.1016/j.jelechem.2013.07.024.

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Delfino, Fabiana Antonia Arena, Denise Bevilaqua, and Assis Vicente Benedetti. "EIS Studies of Chalcopyrite Involving Iron(II) Ions." Solid State Phenomena 262 (August 2017): 496–500. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.496.

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In this work, we present an Electrochemical Impedance Spectroscopy (EIS) study using a carbon paste electrode modified with chalcopyrite (CuFeS2) containing 50 wt% of the mineral (particle size < 38 μm) and graphite (particle size < 20 μm) in naturally aerated salt acid solutions (pH 1.8) without and with the addition of 0.100 mol L-1 of ferrous ions. The aim was to evaluate the influence of the solution potential on the behavior of chalcopyrite electrode in the presence and absence of iron (II) ions. Additionally, we evaluated the influence of the bacteria Acidithiobacillus ferrooxidans in the system containing iron (II) ions without applying potential. Therefore, EIS was used to investigate the processes occurring at the electrode/solution interface in the different systems, considering the charge transfer reactions involving chalcopyrite and ferrous ions, the presence of a multicomponent layer, and diffusion. The results showed that the combination of iron (II) ions with the imposition of low potential values (0.100 Fe2+ ions with +0.300 V/Ag|AgCl|KCl3mol/L) activates the chalcopyrite surface and enhances the copper recovery.

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Shirahatti, Ravi V., and L. Nagesh. "Effect of Fennel Seeds On Dental Plaque and Salivary pH-A Clinical Study." Journal of Oral Health and Community Dentistry 4, no. 2 (2010): 38–41. http://dx.doi.org/10.5005/johcd-4-2-38.

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ABSTRACT Aim Numerous types of practices have been developed over a period of time and have been traditionally followed by various cultures. Chewing of fennel seeds is one of such practices. Scientifically known as foeniculum vulgare, seeds of this plant are commonly chewed after food in Indian sub-continent. Aim of this study was to know the effect of chewing fennel seeds on plaque pH and salivary pH. Materials and Method Twenty subjects were recruited based on eligibility criteria and were informed not to use any oral hygiene measures 24 hours prior to appointment. Plaque was collected to represent buccal surfaces of posterior teeth. For measurement of salivary pH, 2 ml of stimulated saliva was collected. Baseline pH was determined for both plaque and saliva using a calibrated glass combination electrode. After the subjects chewed seeds for five minutes resultant plaque and salivary pH were measured again. A third saliva sample was taken and pH measured five minutes later. Results A highly significant but a very transient drop in salivary pH on chewing the seeds was observed. However plaque pH did not show any significant change. Conclusion The drop in pH is not sustained and is returning to normal limits within five minutes after chewing the seeds suggesting that the seeds have very little Cariogenic potential.

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Anes, Bárbara, Ricardo J. N. Bettencourt da Silva, Cristina Oliveira, and M. Filomena Camões. "Seawater pH measurements with a combination glass electrode and high ionic strength TRIS-TRIS HCl reference buffers – An uncertainty evaluation approach." Talanta 193 (February 2019): 118–22. http://dx.doi.org/10.1016/j.talanta.2018.09.075.

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von Cossel, Moritz, Harm Druecker, and Eberhard Hartung. "Low-Input Estimation of Site-Specific Lime Demand Based on Apparent Soil Electrical Conductivity and In Situ Determined Topsoil pH." Sensors 19, no. 23 (November 30, 2019): 5280. http://dx.doi.org/10.3390/s19235280.

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Site-specific liming helps increase efficiency in agricultural production. For adequate determination of the lime demand, a combination of apparent soil electrical conductivity (ECa) and topsoil pH can be used. Here, it was hypothesized that this can also be done at low-input level. Field measurements using the EM38 MK I (Geonics, Canada) were conducted on three experimental sites in north Germany in 2011. The topsoil pH was measured based on two approaches: on the field using a handheld pH meter (Spectrum-Technologies Ltd., Bridgend, UK) with a flat electrode (in situ), and in the lab using standard equipment (ex situ). Both soil ECa (0.4–35.9 mS m−1) and pH (5.13–7.41) were heterogeneously distributed across the sites. The same was true of the lime demand (−1.35–4.18 Mg ha−1). There was a significant correlation between in situ and ex situ determined topsoil pH (r = 0.89; p < 0.0001). This correlation was further improved through non-linear regression (r = 0.92; p < 0.0001). Thus, in situ topsoil pH was found suitable for map-overlay with ECa to determine the site-specific lime demand. Consequently, the hypothesis could be confirmed: The combined use of data from EM38 and handheld pH meters is a promising low-input approach that may help implement site-specific liming in developing countries.

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Correia-Sá, Luísa, Cristina Soares, Olga Matos Freitas, Manuela Maria Moreira, Henri Petrus Antonius Nouws, Manuela Correia, Paula Paíga, et al. "A Three-Dimensional Electrochemical Process for the Removal of Carbamazepine." Applied Sciences 11, no. 14 (July 12, 2021): 6432. http://dx.doi.org/10.3390/app11146432.

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The scientific community is increasingly concerned about the presence of pharmaceuticals in the aquatic environment, which is a consequence of their high consumption and inefficient removal by wastewater-treatment plants. The search for an effective and sustainable tertiary treatment is therefore needed to enhance their removal. For this purpose, the combination of electrochemical and adsorption processes into three-dimensional (3D) electrochemical systems has been proposed. In this study, a 3D system was studied to remove carbamazepine, an antiepileptic, consumed in high doses and very persistent in the environment. The influences of the following parameters on its removal were evaluated: anode and cathode materials and distance between them, electrolyte (NaCl) concentration and pH, and the (carbon-based) adsorbent material used as the particulate electrode. The obtained results demonstrated that the introduction of the particulate electrode improved the removal efficiency. This can be attributed to the simultaneous occurrence of different phenomena, such as adsorption/electrosorption, electrocoagulation, oxidation, and catalytic degradation.

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Wang, Xiao Hui, Hui Ling Wang, and Zhi Hui Bai. "A Novel Microbial Biosensor for Toxicity Test." Advanced Materials Research 726-731 (August 2013): 1204–8. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1204.

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A mercury chloride sensitive Bacillus sp. X4 as a toxicity recognition element was isolated from soil. A novel microbial biosensor was developed based on the isolated X4 in combination with a dissolved oxygen electrode for the analysis of toxicity in wastewater. Optimal response of the biosensor was obtained at pH 7.0 - 7.5 and 30 - 35 °C with a detection linearity over the range 0.10 - 1.97 mg·L-1 of HgCl2. The repeatability of the sensor response were found to be 1.8%. Preliminary application of the biosensor in pharmacy wastewaters has demonstrated their effectiveness. Toxicity values produced with this biosensor for pharmacy wastewaters correlated well with those determined by standard method.

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Dao, Khanh Chau, Chih-Chi Yang, Ku-Fan Chen, and Yung-Pin Tsai. "Recent Trends in Removal Pharmaceuticals and Personal Care Products by Electrochemical Oxidation and Combined Systems." Water 12, no. 4 (April 7, 2020): 1043. http://dx.doi.org/10.3390/w12041043.

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Due to various potential toxicological threats to living organisms even at low concentrations, pharmaceuticals and personal care products in natural water are seen as an emerging environmental issue. The low efficiency of removal of pharmaceuticals and personal care products by conventional wastewater treatment plants calls for more efficient technology. Research on advanced oxidation processes has recently become a hot topic as it has been shown that these technologies can effectively oxidize most organic contaminants to inorganic carbon through mineralization. Among the advanced oxidation processes, the electrochemical advanced oxidation processes and, in general, electrochemical oxidation or anodic oxidation have shown good prospects at the lab-scale for the elimination of contamination caused by the presence of residual pharmaceuticals and personal care products in aqueous systems. This paper reviewed the effectiveness of electrochemical oxidation in removing pharmaceuticals and personal care products from liquid solutions, alone or in combination with other treatment processes, in the last 10 years. Reactor designs and configurations, electrode materials, operational factors (initial concentration, supporting electrolytes, current density, temperature, pH, stirring rate, electrode spacing, and fluid velocity) were also investigated.

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Das, Sovik, Pritha Chatterjee, and M. M. Ghangrekar. "Increasing methane content in biogas and simultaneous value added product recovery using microbial electrosynthesis." Water Science and Technology 77, no. 5 (January 4, 2018): 1293–302. http://dx.doi.org/10.2166/wst.2018.002.

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Abstract Electrosynthesis of multi-carbon compounds from the carbon dioxide present in biogas is a nascent approach towards purification of biogas. Microbial electrosynthesis (MES) cells, fabricated using different electrode materials, were operated using different electrolytes and mixed anaerobic culture as biocatalysts in the cathodic chamber under an applied cathode potential of −0.7 V vs standard hydrogen electrode (SHE). The rate of production of acetate, isobutyrate, propionate and 2-piperidinone from reduction of CO2 in the cathodic chamber of the MES was 0.81 mM/day, 0.63 mM/day, 0.44 mM/day and 0.53 mM/day, respectively. As methane was also present in the biogas, methyl derivatives of these acids were also found in traces in catholyte. It was observed that the use of nickel foam as an anode, 1 M NiSO4 solution as anolyte, graphite felt as a cathode, phosphate buffer solution as catholyte at a pH of 5.2 proved to be the best possible combination for MES for this study to get enhanced product yield at higher energy efficiency.

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Zimmermann, Peter, Andreas Weltin, Gerald Urban, and Jochen Kieninger. "Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes." Sensors 18, no. 8 (July 24, 2018): 2404. http://dx.doi.org/10.3390/s18082404.

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Potentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter.

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Wang, Qian, Chunmeng Gu, Yafen Fu, Liangliang Liu, and Yixi Xie. "Ultrasensitive Electrochemical Sensor for Luteolin Based on Zirconium Metal-Organic Framework UiO-66/Reduced Graphene Oxide Composite Modified Glass Carbon Electrode." Molecules 25, no. 19 (October 5, 2020): 4557. http://dx.doi.org/10.3390/molecules25194557.

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Luteolin is a kind of natural flavonoid with many bioactivities purified from a variety of natural herbs, fruits and vegetables. Electrochemical sensing has become an outstanding technology for the detection of luteolin in low concentration due to its fast response, easy operation and low cost. In this study, electroreduced graphene oxide (ErGO) and UiO-66 were successively modified onto a glassy carbon electrode (UiO-66/ErGO/GCE) and applied to the detection of luteolin. A combination of UiO-66 and ErGO showed the highest promotion in the oxidation peak current for luteolin compared with those of a single component. The factors affecting the electrochemical behavior of UiO-66/ErGO/GCE were evaluated and optimized including pH, accumulation potential, accumulation time and scan rate. Under optimum conditions, UiO-66/ErGO/GCE showed satisfactory linearity (from 0.001 μM to 20 μM), reproducibility and storage stability. The detection limit of UiO-66/ErGO/GCE reached 0.75 nM of luteolin and was suitable for testing real samples. Stable detection could be provided at least eight times by one modified electrode, which guaranteed the practicability of the proposed sensor. The fabricated UiO-66/ErGO/GCE showed a rapid electrochemical response and low consumption of materials in the detection of luteolin. It also showed satisfactory accuracy for real samples with good recovery. In conclusion, the modification using MOFs and graphene materials made the electrode advanced property in electrochemical sensing of natural active compounds.

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Heidari, Alireza. "Synthesis of Fructose Biosensors and Progressing Their Efficiency Using Californium Colloidal Nanoparticles for Detecting Fructose and Triglycerides." Advanced Science, Engineering and Medicine 12, no. 8 (August 1, 2020): 1002–17. http://dx.doi.org/10.1166/asem.2020.2635.

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In the current paper, fructose–oxidase enzyme is used as stabilization medium due to its more efficiency, ability for more accurate controlling the enzyme reaction, protecting against wasting of enzyme as well as simple and easy use and exchange of enzyme medium after performing some levels of surface modification and developing multi–walled carbon nanotubes (MWCNTs) on Californium plate. For better connecting and stabilizing the enzyme on the medium, the prepared medium is washed by high concentration sulfuric acid and nitric acid and a large volume of deionized water and for protecting enzyme from devastating effect of Californium and prohibiting them to become inactive, surface is covered with cystamine before stabilization. Regarding the large size of fructose–oxidase enzyme compared to surface of medium, a connective material with amid at one end and pyrine at the other end is used as transfer agent and for stabilizing this connection, the prepared medium is placed into dimethylformamide (DMF) solution for a couple of hours. Activity of stabilized enzyme at 460 (nm) wavelength recorded by spectroscope was depicted against time to evaluate its stability in various times. The prepared medium, which have a large amount of fructose–oxidase enzyme, can be used as electrode in sensors. Furthermore, fructose–oxidase electrochemical sensor is one of the best methods for detecting low amount of fructose and applying Californium colloidal nanoparticles as a supplementary material in the structure of biosensor can be effective for progressing its efficiency and optimum efficiency. On the other hand, in the current study, electrode biosensor entitled as modified carbon paste electrode with Californium colloidal nanoparticles (Cfnano/CPE) is produced by carbon graphite powder, paraffin oil and Californium colloidal nanoparticles (24 nm) and it is compared with carbon paste electrode (CP). In semi–permeable membranes, a combination of 1 (ml) of 0.1 (M) phosphate buffer with specified pH and 10 (mg) of fructose–oxidase enzyme is placed around each electrode. In the same potential of 0.7 (V), biosensors are tested with fructose in concentration range of (0−1) (mM) and various amounts of pH (4,6,8) which lead to producing the maximum current and tracing fructose in pH=6 and concentration of 1 (M) as the optimum condition. Currentmetry induced from both biosensors are compared and it is confirmed that using Californium colloidal nanoparticles in the structure of (Cfnano/CPE) electrode leads to increasing the conductivity and currentmerty of biosensor. In addition, qualitative and quantitative measurement of food components is of great importance due to high cost of traditional methods, in addition to tendency for more accurate and sensitive detecting of these components. Fructose and triglycerides are such compounds that they frequently measure. Various methods are used to detect these food elements. However, the necessity for accurate measurement of these two compounds with high sensitivity, especially for food health issue, leads to developing biological methods, especially biosensors. Among them, biosensors based on conductive polymer nanostructures, especially Polypyrrole and Polythiophene, have been recently interested due to their unique characteristics. The current paper aims to introduce and investigate the previously performed studies about Polypyrrole and Polythiophene–based biosensors for detecting fructose and triglycerides.

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Zeng, Jie, Min Ji, Yingxin Zhao, Thomas Helmer Pedersen, and Hao Wang. "Optimization of electrocoagulation process parameters for enhancing phosphate removal in a biofilm-electrocoagulation system." Water Science and Technology 83, no. 10 (April 5, 2021): 2560–74. http://dx.doi.org/10.2166/wst.2021.132.

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Abstract This study aimed to enhance the removal of phosphate in synthetic rural sewage by using a continuous electrocoagulation (EC) combined with biofilm process in an integrated system. Characteristic indexes of biofilm process effluent covering pH, dissolved oxygen (DO), suspended solids (SS), chemical oxygen demand (COD) and phosphate maintained a narrow fluctuation range and tended not readily to influence the phosphate removal of subsequent electrocoagulation. Three parameters including inter-electrode distance, current intensity and reaction time were selected to investigate the performance of enhancing phosphate removal. On the strength of single-factor tests, the Box-Behnken design (BBD) coupled with response surface methodology (RSM) was applied to investigate the individual and mutual interaction impacts of the major operating parameters and to optimize conditions. The optimum conditions were found to be inter-electrode distance of 1.8 cm, current density of 2.1 mA/cm2 and EC reaction time of 34 min, and phosphate removal efficiency of 90.24% was achieved along with less than 1 mg/L in case of periodic polarity switching mode, which raised removal efficiency by 10.10% and reduced operating cost by 0.13 CNY/g PO4− compared to non-switching mode. The combination of biofilm processing and electrocoagulation treatment was proven to be a valid and feasible method for enhancing phosphate removal.

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Wang, Lixin, Peipei Zhang, Lei Bai, Lei Cao, Jing Du, Yazhou Wang, and Xiujuan Qin. "Effects of Electrodeposition Time on Ni/rGO Composite Electrode as an Efficient Catalyst for Hydrogen Evolution Reaction in Alkaline Media." Current Nanoscience 15, no. 2 (December 14, 2018): 178–87. http://dx.doi.org/10.2174/1573413714666180405142110.

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Background: Ni/rGO composite electrode has been fabricated by facile supergravity electrodeposition as a low-cost catalyst for efficient hydrogen evolution in alkaline media. In this paper, the electrodeposition time is the main research variable. When the electrodeposition time is 100 minutes, the Ni/rGO-100 catalyst manifests the highest electrocatalytic activity toward the hydrogen evolution reaction (HER). In 1.0 M NaOH solution, the overpotential at a current density of 100 mA cm-2, Tafel slope and charge transfer resistance of Ni/rGO-100 catalyst is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. In addition, Ni/rGO-100 catalyst shows a long-term durability at a constant current density of 100 mA cm-2 for 10 h. The outstanding HER electrocatalytic performance of the Ni/rGO-100 is mainly related to the synergetic combination of Ni and rGO, as well as the enlarged exposure of catalytically active sites and improved transport of electrons arising from the good conductivity of graphene. Method: In a classic experiment, GO was prepared by modified Hummers method. The Ni/rGO composite electrodes were prepared by supergravity electrodeposition, which has been reported in detail in our published paper. Firstly, a ø10 cm × 2 cm Ni foam circle was cleaned sequentially in HCl solution (15%), acetone and DI water for 5 min with ultrasonication to be used as a cathode. And a pure nickel pipe was used as anode. The Ni/rGO composite cathodes were electrodeposited in a blackish green plating bath which contained 350 g L-1 Ni(NH2SO3)2·6H2O, 10g L-1 NiCl2·6H2O, 30 g L-1 NH4Cl , 1.0 g L-1 GO colloidal solution with different electrodeposition time, 10min, 30min, 60min, 80min, 100min, respectively. The pH value of the plating bath is 3.5-3.8. The above five electrodes were respectively denominated as Ni/rGO-10, Ni/rGO-30, Ni/rGO-60, Ni/rGO-80, Ni/rGO-100. All composite electrodes were performed under the strength of the supergravity with G=350 g at a current density of 3 A dm-2 at 318 K. Afterwards the Ni foam coated with Ni/rGO hybrid was taken out of the reaction vessel, followed by washing with deionized water to remove physical adsorption residua, and then dried at 80°C. Results: In this paper, the electrodeposition time is the main research variable. When the electrodeposition time is 100 minutes, the Ni/rGO-100 catalyst manifests the highest electrocatalytic activity toward the hydrogen evolution reaction (HER). In 1.0 M NaOH solution, the overpotential at a current density of 100 mA cm-2, Tafel slope and charge transfer resistance of Ni/rGO-100 catalyst is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. In summary, we have synthesized a class of composite electrodes (Ni/rGO) for HER in alkaline solution by electrodeposition under supergravity field. We studied the effect of electrodeposition time on electrode performance in detail. With the increase of electrodeposition time, the number of active sites is enlarged provided by the electrode. When the electrodeposition time is 100 min, we fabricate the best electrode (Ni/rGO-100). The η100, Tafel slope and charge transfer resistance of Ni/rGO-100 is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. The introduction of graphene and supergravity field plays a key role in improving the performance of the electrodes. This work is a pivotal part of the development of Ni/rGO as a non-precious HER catalyst for green energy field.

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Wang, H., X. J. Wei, and Z. Y. Bian. "Degradation of 4-chlorophenol by the anodic–cathodic cooperative effect with a Pd/MWNT gas-diffusion electrode." Water Science and Technology 65, no. 11 (June 1, 2012): 2010–15. http://dx.doi.org/10.2166/wst.2012.104.

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Pd/multi-walled carbon nanotubes (MWNTs) catalyst used for the gas-diffusion electrode was prepared by ethylene glycol (EG) reduction and characterized by the X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that Pd particles with an average size of 8.0 nm were highly dispersed in the MWNTs with amorphous structure. In a diaphragm electrolysis system with a Ti/RuO2/IrO2 anode and the Pd/MWNT gas diffusion cathode, the degradation of 4-chlorophenol was performed by a combination of electrochemical reduction and oxidation. The combined process was in favor of improving 4-chlorophenol degradation efficiency. The optimum reaction conditions were as following: initial pH 7, aeration with hydrogen and air. Under the optimized electrolysis conditions the removal of 4-chlorophenol in the anodic and cathodic compartments were 98.5 and 90.5%, respectively. Additionally, based on the analysis of electrolysis intermediates using high performance liquid chromatography (HPLC) and ion chromatography (IC), the electrolysis degradation of 4-chlorophenol was proposed containing the intermediates, such as phenol, hydroquinone, benzoquinone, maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid, acetic acid and formic acid.

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47

Yuliani, G., R. Agustiningsih, H. S. Halimatul Munawaroh, and N. F. Rahmi. "The Use of Coagulation-UV Irradiation/H₂O₂ and Electrocoagulation Methods on Pulp and Paper Mill Wastewater Treatment." Solid State Phenomena 280 (August 2018): 393–98. http://dx.doi.org/10.4028/www.scientific.net/ssp.280.393.

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Effluents from pulp and paper mill typically consist of high loading of inorganics compounds (e.g., Na2CO3, Na2S, NaOH and NaCl) and organics compounds (e.g., lignin and polysaccharides fragments, alcohols, carboxylic acids) Several methods, such as biological, physical and chemical treatment, have been reported to degrade these molecules. However, coagulation is by far the cheapest, simplest and most common method employed for secondary wastewater treatment to reduce colour and organics. In this research, two most widely used methods were employed to treat a model wastewater of pulp and paper industry, namely a combination of coagulation-flocculation-UV irradiation/H2O2 and electrocoagulation (EC). In the application of coagulation-flocculation-UV irradiation/H2O2 method, the decrease in colour (measured as absorbance at 500 nm) was 71%, and the COD removal was measured to be 38% under the optimum conditions of pH 8, coagulant dose of 700 ppm, flocculant dose of 60 ppm, 130 rpm of coagulant stirring rate, 1 day irradiation time, and 25 mM of H2O2. For the EC method, 91% reduction of color and 84% reduction of COD were achieved at 40 min of electrolysis time, pH of 8, 600 ppm of NaCl concentration, electrode distance of 1.5 cm and 2 V of voltage. The EC method may serve as an efficient method for color and organics removals from pulp and paper mill wastewater.

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Baek, Jiyun, Changman Kim, Young Song, Hyeon Im, Mutyala Sakuntala, and Jung Kim. "Separation of Acetate Produced from C1 Gas Fermentation Using an Electrodialysis-Based Bioelectrochemical System." Energies 11, no. 10 (October 16, 2018): 2770. http://dx.doi.org/10.3390/en11102770.

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The conversion of C1 gas feedstock, such as carbon monoxide (CO), to useful platform chemicals has attracted considerable interest in industrial biotechnology. One conversion method is electrode-based electron transfer to microorganisms using bioelectrochemical systems (BESs). In this BES system, acetate is the predominant component of various volatile fatty acids (VFAs). To appropriately separate and concentrate the acetate produced, a BES-type electrodialysis cell with an anion exchange membrane was constructed and evaluated under various operational conditions, such as applied external current, acetate concentration, and pH. A high acetate flux of 23.9 mmol/m2∙h was observed under a −15 mA current in an electrodialysis-based bioelectrochemical system. In addition, the initial acetate concentration affected the separation efficiency and transportation rate. The maximum flux appeared at 48.6 mmol/m2∙h when the acetate concentration was 100 mM, whereas the effects of the initial pH of the anolyte were negligible. The acetate flux was 14.9 mmol/m2∙h when actual fermentation broth from BES-based CO fermentation was used as a catholyte. A comparison of the synthetic broth with the actual fermentation broth suggests that unknown substances and metabolites produced from the previous bioconversion process interfere with electrodialysis. These results provide information on the optimal conditions for the separation of VFAs produced by C1 gas fermentation through electrodialysis and a combination of a BES and electrodialysis.

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Cook, Peter, YoungJae Kim, Ke Yuan, Maria C. Marcano, and Udo Becker. "Electrochemical, Spectroscopic, and Computational Investigations on Redox Reactions of Selenium Species on Galena Surfaces." Minerals 9, no. 7 (July 15, 2019): 437. http://dx.doi.org/10.3390/min9070437.

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Despite previous studies investigating selenium (Se) redox reactions in the presence of semiconducting minerals, Se redox reactions mediated by galena (PbS) are poorly understood. In this study, the redox chemistry of Se on galena is investigated over a range of environmentally relevant Eh and pH conditions (+0.3 to −0.6 V vs. standard hydrogen electrode, SHE; pH 4.6) using a combination of electrochemical, spectroscopic, and computational approaches. Cyclic voltammetry (CV) measurements reveal one anodic/cathodic peak pair at a midpoint potential of +30 mV (vs. SHE) that represents reduction and oxidation between HSeO3− and H2Se/HSe−. Two peak pairs with midpoint potentials of −400 and −520 mV represent the redox transformation from Se(0) to HSe− and H2Se species, respectively. The changes in Gibbs free energies of adsorption of Se species on galena surfaces as a function of Se oxidation state were modeled using quantum-mechanical calculations and the resulting electrochemical peak shifts are (−0.17 eV for HSeO3−/H2Se, −0.07 eV for HSeO3−/HSe−, 0.15 eV for Se(0)/HSe−, and −0.15 eV for Se(0)/H2Se). These shifts explain deviation between Nernstian equilibrium redox potentials and observed midpoint potentials. X-ray photoelectron spectroscopy (XPS) analysis reveals the formation of Se(0) potentials below −100 mV and Se(0) and Se(−II) species at potentials below −400 mV.

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Neupane, Shova, Suresh Bhusal, Vivek Subedi, Krishna Badan Nakarmi, Dipak Kumar Gupta, Ram Jeewan Yadav, and Amar Prasad Yadav. "Preparation of an Amperometric Glucose Biosensor on Polyaniline-Coated Graphite." Journal of Sensors 2021 (January 28, 2021): 1–7. http://dx.doi.org/10.1155/2021/8832748.

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Control of glucose concentration has tremendous significance in medical diagnosis, pharmaceuticals, food, and fermentation industries. Herein, we report on the fabrication of a facile, low-cost, and sensitive enzyme-based amperometric sensor using the electrochemically deposited polyaniline (PANI) film on a graphite electrode. PANI was deposited from an aqueous solution of 0.2 M aniline in 1.0 M hydrocholoric acid (HCl) by cyclic voltammetry (CV). Surface morphology and composition characterization of the PANI film were carried out by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FTIR) spectroscopy. Potentiostatic immobilization of glucose oxidase (GOX) enzyme in the PANI film was carried out at 0.75 V to fabricate an amperometric glucose biosensor (GOx/PANI/graphite biosensor). The glucose concentration response of the prepared sensor was studied amperometrically by detecting hydrogen peroxide (H2O2). The detection of H2O2 was optimized by calibrating the effects of pH, reduction potential, and background current. A reduction potential of -0.4 V at pH 6 was the best combination to get a maximum amperometric response of the GOx/PANI/graphite biosensor. A stable current response was obtained in 4 min with a high reproducibility in linearity within the concentration range of 0.01 M-0.1 M D-glucose. Therefore, the fabricated GOx/PANI/graphite biosensor could be a promising candidate for glucose sensing.

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Journal articles on the topic 'PH combination electrode'

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