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1
Ondon, Brim Stevy, Bing Sun, Zhi Yu Yan, Xiao Mei Zhu y Hui Liu. "Microwave Preparation of Modified Activated Carbons for Phenol Adsorption in Aqueous Solution". Advanced Materials Research 726-731 (agosto de 2013): 1883–89. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1883.
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Microwave energy was used to prepare modified activated carbons (GAC, GAC/MW, GAC/Ni, and GAC/Cu). The modified activated carbons were used for phenol adsorption in aqueous solution. The adsorption conditions were optimized. Adsorption capacities of the different modified activated carbons were evaluated. The effect of microwave pretreatment of activated carbons was investigated. A comparative study on the activated carbons adsorption capacities was also investigated. Under optimal conditions the results showed that there was no obvious effect on activated carbons adsorption when rising temperature and pH during the adsorption process. Stirring has a very high effect on the activated carbons adsorption capacity. The adsorption capacity of the modified activated carbons reaches 95%. MW/GAC, GAC/Ni and GAC/Cu adsorptive capacity was higher compared to the Granulated Activated Carbon (GAC) used as received. GAC treated with microwave energy has highest adsorption capacity. The adsorption capacity of GAC loaded with ion Ni2+ is higher than the activated carbon loaded with Cu2+. The untreated GAC has the lowest adsorption capacity. These results can be explained by the effect of microwave irradiation on GAC.The activated carbon loaded with Ni2+ adsorbs more microwave energy than the GAC loaded with Cu2+.
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Bastami, Sina, Sina Ghassa, Amin Seyedhakimi y Saeed Chehreh Chelgani. "Adsorption of Mercury from a Cyanide Leaching Solution Using Various Activation Rates of Granular Activated Carbon: A Laboratory- and Industrial-Scale Study". Sustainability 12, n.º 8 (17 de abril de 2020): 3287. http://dx.doi.org/10.3390/su12083287.
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The use of granular activated carbon (GAC) is a typical and sustainable technique for recovering precious metals from a cyanide leaching solution (CLS). The level of GAC activity is a fundamental factor in assessing the rate of precious metal adsorption; thus, it is essential to determine the efficiency of carbon elution for reproducing GACs. Since mercury (Hg) adsorption plays a critical role, economically and environmentally, in GAC efficiency, we conducted various laboratory and industrial experiments to explore the effect of different rates of GAC activation (10%, 35%, 70% and 100%) on Hg adsorption from CLS. Assessments of laboratory test results showed a direct relationship between the Hg adsorption and GAC activity; by increasing the GAC activity from 10% to 100%, the recovery of Hg was increased from 20% to 41%. Kinetic modeling results indicated that the Hg adsorption for all GAC activities followed chemisorption mechanisms. There was good agreement between the laboratory test results and the results of experiments on the industrial scale (that used a continuous circuit). These outcomes indicate that by increasing the frequency of carbon reactivation and using GAC with a high level of activity in the first tank, Hg desorption was meaningfully decreased and recovery was improved (for 10% GAC activity vs. 35% GAC activity, recovery was 40% vs. 90%, respectively).
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Son, Heejong, Sangki Choi, Byungryul An, Hyejin Lee y Hoon-Sik Yoom. "Effect of Changes in Physical Properties of Granular Activated Carbon (GAC) on the Adsorption of Natural Organic Matter (NOM) with Increasing the Number of Thermal Regeneration: Pore Size and NOM Molecular Weight". Journal of Korean Society of Environmental Engineers 43, n.º 7 (31 de julio de 2021): 537–46. http://dx.doi.org/10.4491/ksee.2021.43.7.537.
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Objectives : The purpose of this study was to evaluate the effect of increasing the number of regeneration of granular activated carbon (GAC) on the adsorption capacity of natural organic matter (NOM), and to suggest the technical process options associated the limit number of regeneration and the efficient use of regenerated GAC.Methods : The physicochemical properties of virgin and thermally regenerated GAC were analyzed. To evaluate the NOM adsorption capacity of virgin- and regenerated-GAC, five laboratory-scale columns packed with virgin- and regenerated-GAC were used for treating effluent from pilot-scale drinking water treatment facility. The NOM concentration in the influent and the effluent treated by each column was analyzed by LC-OCD (liquid chromatography-organic carbon detector) to evaluate the adsorption capacity of each NOM fractions (humic substances (HS), building blocks (BB), low molecular weight organics (LMWs)).Results and Discussion : Due to the change in the pore structure of GAC by thermal regeneration, the volume of micropores (< 2 nm) decreased, while the volume of mesopores (> 2 nm) increased. The volume ratio of micropore in virgin-GAC was about 60%, but it gradually decreased as the number of regenerations increased, resulting that the volume ratio of micropore in the 5th-regenerated (5th-Re) GAC decreased to 23%. On the other hand, the volume ratio of mesopore increased in proportion to the number of regenerations from 40% of the virgin GAC to 77% of the 5th-Re-GAC. The DOC adsorption capacities of the regenerated GACs were higher than that of virgin GAC, and the DOC adsorption capacity increased as the number of regenerations increased. As a result of comparing the adsorption capacity of virgin- and regenerated-GAC by NOM fractions, the adsorption capacity of high molecular weight NOM, such as HS, increased by 1.5 to 1.7 times as the number of regenerations increased. In contrast, the adsorption capacity of low molecular weight NOM, such as BB and LMWs, decreased by 78% and 48% as the number of regeneration increased. The limit number of regeneration was evaluated based on that the adsorption capacity (qe) of each NOM fractions keep over than 70% relative to its virgin GAC. As a result, the adsorption capacity for low molecular weight NOM was greatly reduced in GAC regenerated over than 3rd time, so that the 2nd-Re-GAC was valid to keep 70% removal of whole NOM fractions. Low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.Conclusions : Due to the change in the pore structure of GAC by thermal regeneration, the DOC adsorption capacity was higher in regenerated GAC than its virgin-GAC, and the adsorption capacity of DOC and high molecular weight NOM (HS) was enhanced as the number of regenerations increased. On the other hand, the pore volume of micropore was reduced by regenerations, and in more than 3rd times regenerations, the adsorption capacity of low molecular weight NOMs (BB and LMWs) was reduced by less than 70% compared to its virgin GAC, so that 2nd-Re-GAC was suggested for suitable GAC. When using a mixture of virgin- and 3rd-Re-GAC, low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.
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Roddaeng, Songkiat, Pongjet Promvonge y Rewadee Anuwattana. "Behaviors of hydrogen sulfide removal using granular activated carbon and modified granular activated carbon". MATEC Web of Conferences 192 (2018): 03037. http://dx.doi.org/10.1051/matecconf/201819203037.
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An experimental study on hydrogen sulphide (H2S) adsorption behaviours using amine-impregnated solid adsorbent (GAC/PEI) was carried out for H2S concentration in the range of 200 and 400 ppm. The dynamic adsorptions of GAC and modified GAC (2.0 and 1000 g/L PEI) in a fixed-bed column were investigated by determining the breakthrough curves and adsorption capacities of various adsorbents. The adsorbent exhibits an excellent adsorption capacity of 106.87 and 231.45 mgH2S/g-adsorbent for 200 ppm and 400 ppm H2S, respectively. The H2S breakthrough capacity is found to relate to the surface adsorption and chemical adsorption.
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Kim, Taehoon y Byungryul An. "Effect of Hydrogen Ion Presence in Adsorbent and Solution to Enhance Phosphate Adsorption". Applied Sciences 11, n.º 6 (20 de marzo de 2021): 2777. http://dx.doi.org/10.3390/app11062777.
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In this paper, the effect of hydrogen ions on the adsorption onto granular activated carbon (GAC) with the inorganic contaminant phosphate, which exists as a form of four species depending on the solution pH, is investigated. Various batch isotherm and kinetic experiments were conducted in an initial pH 4 as an acid, a pH 7 as neutral, and a pH 9 solution as a base for the GAC conditioned with deionized water and hydrochloric acid, referred to as GAC and GACA, respectively. The physical properties, such as the total surface area, pore volume, pore size distribution, and weight of the element, obtained from Brunauer–Emmett–Teller (BET) and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM–EDX) represent no significant differences. However, the hydrochloric acid (HCl) condition results in an alteration of the pH of the point of zero charge from 4.5 to 6.0. The optimized initial pH was determined as being acid for the GAC and as being neutral for the GACA. According to the Langmuir isotherm, the relatively high Qm was obtained as being acid for the GAC and clearly distinguishes the pH effect as being the base for the GACA. An attempt was made to assess the adsorption mechanism using the pseudo-first-order (PFO), the pseudo-second-order (PSO), and the intraparticle diffusion models. The higher R2 for the PSO in the entire pH range indicated that chemisorption was predominant for phosphate adsorption, and the pH did not change the adsorption mechanism. A prolonged Bed Volume (BV) for the GACA demonstrated that the hydrogen ions on the surface of the GAC enhanced phosphate adsorption.
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Zhaoyang, Lu, Jiang Bicun y Li Aimin. "Effects of the functional groups attached to aromatic organic compounds on their adsorption onto preloaded activated carbon". Water Science and Technology 66, n.º 8 (1 de octubre de 2012): 1799–805. http://dx.doi.org/10.2166/wst.2012.349.
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The adsorption of phenol, p-nitrophenol, aniline, and nitrobenzene onto a commercial granular activated carbon (GAC: F400) preloaded with tannic acid (TA), a model background contaminant, was investigated. Compared with virgin GAC, the adsorption capacities of the four selected aromatic organic compounds (AOCs) onto GACs preloaded with TA at three densities were affected significantly. Also, the relationship between the adsorption capacities of AOCs and the characteristics of GACs was further discussed and clarified in this manuscript. The differences in the functional groups attached to the AOCs did not affect the similar linear relationship between the micropore surface area and their capacities to AOCs. However, the adsorption capacities of AOCs on TA-loaded GAC were affected by the different functional groups on the four AOCs: 67.6% of the capacity of aniline for virgin F400 remained on F400c (a preloaded GAC), compared with 23.8, 25.9, and 36.5% of phenol, p-nitrophenol, and nitrobenzene, respectively. The diversity of adsorption behavior of the four AOCs with different substituents was the result of hybrid contributions, such as hydrogen bonding, hydrophobic effect and aromatic stacking.
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Son, Heejong, Hoon-Sik Yoom, Chang-Dong Seo, Sang-Goo Kim y Yong-Soon Kim. "Evaluation of Dissolved Organic Matter Removal Characteristics in GAC Adsorption Process in Drinking Water Treatment Process using LC-OCD-OND". Journal of Korean Society of Environmental Engineers 42, n.º 5 (31 de mayo de 2020): 239–50. http://dx.doi.org/10.4491/ksee.2020.42.5.239.
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Objectives:In this study, we used liquid chromatograph-organic carbon detector-organic nitrogen detector (LC-OCD-OND) to evaluate adsorption and breakthrough characteristics of NOM fractions (biopolymers (BP), humic substances (HS), building blocks (BB) and low molecular weight organic substances (LMW-O)) according to the various characteristics of the different materials of granular activated carbons (GACs).Methods:Breakthrough characteristics, adsorption capacity and partition coefficients were evaluated by NOM fractions (BP, HS, BB, and LMW-O) using a lab-scale GAC adsorption column filled with coal-, coconut- and wood-based GAC. The GAC column test was operated with 10 minutes empty bed contact time (EBCT). The pore characteristics of each GAC were evaluated using an automated gas sorption analyzer (Autosorb iQ3, Quantachrome, USA) and the concentrations of NOM fractions in the influent and effluent were analyzed using chromatography LC-OCD-OND (Model 8, DOC-Labor, Germany).Results and Discussion:NOM adsorption capacity was evaluated for different materials of laboratory scale GAC adsorption column test. To study the adsorption behavior of individual NOM fractions according to the operation time, NOM was fractionated into BP, HS, BB and LMW-O by LC-OCD-OND, and the individual NOM fractions were quantified. Higher MW like BP was not adsorbed to GAC, in contrast, HS, BB, and LMW-O were well removed during the initial operation period, the concentrations in the effluent gradually increased as increase the operation period until reaching to the pseudo steady-state. Poor removal of BP in GAC adsorption may be a result of blocking the pores with large MW BP and hinder the access to the pores. However, in the case of HS, BB, and LMW-O, as the molecular size decreased, these organic matters easily access to the pores inside of GAC. It was confirmed through the partition coefficient that the adsorption capacity of these NOM fractions increased in proportion to the MW. In addition, in order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH<sub>zpc</sub> must be higher than the neutral pH level.Conclusions:In order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pH<sub>zpc</sub> must be higher than the neutral pH level. In addition, in the NOM fractions, BP were not adsorbed to GAC, while the adsorption capacity of the remaining NOM fractions increased as the MW of the NOM fractions decreased. LMW-O was the most adsorbed, followed by BB, HS and BP. BP and HS play an important role in the membrane fouling that are introduced a lot into domestic and foreign water treatment plants. This study showed that the BP was not removed by the adsorption mechanism of the GAC process. In addition, HS was adsorbed and removed at the beginning of the operation, but the adsorption capacity of HS decreased rapidly as the operation period increased compared to other NOM fractions. Therefore, the GAC adsorption process is not expected to be an effective pre-treatment technology for reducing membrane foulants. Previous studies showed that the yields of DBPs (µmol･DBP/µmol･C) in the high MW humic and low MW non-humic fractions are similar. Therefore, it is suggested that the GAC adsorption process is more effective for DBP precursor control in water containing a larger percentage of LMW NOM.
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Ding, Chun Sheng, Qian Fen Zhu, Ping Ning y Jing Ke Lu. "Preparation and Characterization of Modified Activated Carbon and its Influencing Factors of Cd2+ Adsorption". Advanced Materials Research 152-153 (octubre de 2010): 935–39. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.935.
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In order to improve the Cd2+ adsorption ability, the granular activated carbon (GAC) was modified with different treatments, and the Cd2+ removal efficiencies (REs) by the treated GACs were then comparatively investigated under different conditions. The surface physical-chemical properties of these carbons were further characterized in virtue of BET and Boehm’s titration, etc. The results demonstrate that the specific surface area and surface oxy acidity functional groups of GAC changed to some certain after the different treatments, especially for that with HNO3 oxidizing. It therefore led to an improvement of Cd2+ adsorption ability, and the corresponding REs by the N-GACs that were respectively modified with 10% and 70% HNO3 were significantly higher than that by the original GAC (i.e., 41% and 57% vs. 10%). pH was found to be the most vital influencing factor for the Cd2+ adsorption, and the Cd2+ REs by the tested GACs were all increased with an elevation in the pH value.
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Benstoem, F. y J. Pinnekamp. "Characteristic numbers of granular activated carbon for the elimination of micropollutants from effluents of municipal wastewater treatment plants". Water Science and Technology 76, n.º 2 (4 de abril de 2017): 279–85. http://dx.doi.org/10.2166/wst.2017.199.
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Adsorption on granular activated carbon (GAC) is a promising step to extend existing treatment trains in municipal wastewater treatment plants (WWTPs) and, thus, to reduce the concentration of micropollutants (MPs) (e.g. pharmaceuticals) in wastewater. It is common practice to use characteristic numbers when choosing GAC for a specific application. In this study, characteristic numbers were correlated for five different GACs, with measured adsorption capacities of these carbons for three pharmaceutical MPs (carbamazepine, diclofenac and sulfamethoxazole) and dissolved organic carbon of a WWTP effluent. The adsorption capacities were measured using rapid small scale column tests. Density of GAC showed the highest correlation to adsorption of MP. All other characteristic numbers (iodine number, Brunauer–Emmett–Teller (BET) surface and methylene blue titre) are not suitable markers for choosing an appropriate activated carbon product for the elimination of MPs from municipal wastewater.
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Wang, Feifei, Lu Zhang, Liangfu Wei y Jan Peter van der Hoek. "Removal of Hydrogen Peroxide Residuals and By-Product Bromate from Advanced Oxidation Processes by Granular Activated Carbon". Water 13, n.º 18 (7 de septiembre de 2021): 2460. http://dx.doi.org/10.3390/w13182460.
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During drinking water treatment, advanced oxidation process (AOP) with O3 and H2O2 may result in by-products, residual H2O2 and BrO3−. The water containing H2O2 and BrO3− often flows into subsequent granular activated carbon (GAC) filters. A concentrated H2O2 solution can be used as GAC modification reagent at 60 °C to improve its adsorption ability. However, whether low concentrations of H2O2 residuals from AOP can modify GAC, and the impact of H2O2 residuals on BrO3− removal by the subsequent GAC filter at ambient temperature, is unknown. This study evaluated the modification of GAC surface functional groups by residual H2O2 and its effect on BrO3− removal by GAC. Results showed that both H2O2 and BrO3− were effectively removed by virgin GAC, while pre-loaded and regenerated GACs removed H2O2 but not BrO3− anymore. At the ambient temperature 150 µmol/L H2O2 residuals consumed large amounts of functional groups, which resulted in the decrease of BrO3− removal by virgin GAC in the presence of H2O2 residuals. Redox reactions between BrO3− and surface functional groups played a dominant role in BrO3− removal by GAC, and only a small amount of BrO3− was removed by GAC adsorption. The higher the pH, the less BrO3− removal and the more H2O2 removal was observed.
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Ridwan Fahmi, Muhammad, M. N. Nasruddin, Che Zulzikrami Azner Abidin y M. Ali Umi Fazara. "Adsorption of Reactive Red 120 by Using Regenerated Spent Carbon". Applied Mechanics and Materials 754-755 (abril de 2015): 671–75. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.671.
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In this study the performance of regenerated spent carbon for azo dye removal was evaluated in batch and continuous column. The spent carbon was generated by thermal method through pyrolysis process and chemical method by using NaOH 6.0 M solution. Reactive Red 120 (RR120) was selected as a model of azo dye due to its common application in the industries. The regeneration of spent granular activated carbon (GAC) by pyrolysis could produce adsorbent that has the adsorption capacity closer to new GAC. The result indicated that paralysed GAC could potentially apply to replace new GAC for RR120 adsorption. In addition, the continuous adsorption operation in mini column test confirmed that the order of adsorption capacity of each GAC is as follows: new GAC, pirolysed GAC, chemical treated GAC and spent GAC.
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Orlandini, Ervin, Tsegaye G. Gebereselassie, Joop C. Kruithof y Jan C. Schippers. "Effect of ozonation on preloading of background organic matter in granular activated carbon filters". Water Science and Technology 35, n.º 7 (1 de abril de 1997): 295–302. http://dx.doi.org/10.2166/wst.1997.0289.
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Background Organic Matter (BOM) preloading is adsorption of BOM onto Granular Activated Carbon (GAC) prior to the adsorption of target compounds, such as pesticides and other organic micropollutants (e.g. atrazine). BOM preloading is commonly found to speed up the breakthrough of target compounds during GAC filtration. Ozonation of GAC filter influent may be expected to lower BOM preloading, because it results in less adsorbable and more biodegradable BOM compounds. Short Fixed Bed (SFB) tests with virgin and preloaded GAC, performed within this study, confirmed that preloading of BOM present in pretreated river Rhine water speeds up the breakthrough of atrazine in GAC filters. BOM preloading was found to lower equilibrium adsorption capacity of GAC for atrazine, and to slow down both external and internal mass transfer rate of atrazine on/into GAC. Adsorption capacity of (crushed) GAC was determined from atrazine adsorption isotherms, while mass transfer rate coefficients were determined by fitting the Homogeneous Surface Diffusion model to the breakthrough of atrazine in the SFB tests. More pronounced BOM preloading was found in the GAC filter receiving non-ozonated influent than in its ozonated counterpart. Biodegradation of ozonated BOM was shown to lower BOM preloading in GAC filters.
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Grivé, M., D. García, C. Domènech, L. Richard, I. Rojo, X. Martínez y M. Rovira. "A quantitative speciation model for the adsorption of organic pollutants on activated carbon". Water Science and Technology 68, n.º 6 (1 de septiembre de 2013): 1370–76. http://dx.doi.org/10.2166/wst.2013.383.
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Granular activated carbon (GAC) is commonly used as adsorbent in water treatment plants given its high capacity for retaining organic pollutants in aqueous phase. The current knowledge on GAC behaviour is essentially empirical, and no quantitative description of the chemical relationships between GAC surface groups and pollutants has been proposed. In this paper, we describe a quantitative model for the adsorption of atrazine onto GAC surface. The model is based on results of potentiometric titrations and three types of adsorption experiments which have been carried out in order to determine the nature and distribution of the functional groups on the GAC surface, and evaluate the adsorption characteristics of GAC towards atrazine. Potentiometric titrations have indicated the existence of at least two different families of chemical groups on the GAC surface, including phenolic- and benzoic-type surface groups. Adsorption experiments with atrazine have been satisfactorily modelled with the geochemical code PhreeqC, assuming that atrazine is sorbed onto the GAC surface in equilibrium (log Ks = 5.1 ± 0.5). Independent thermodynamic calculations suggest a possible adsorption of atrazine on a benzoic derivative. The present work opens a new approach for improving the adsorption capabilities of GAC towards organic pollutants by modifying its chemical properties.
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Metz, D. H., J. DeMarco, R. Pohlman, F. S. Cannon y B. C. Moore. "Effect of multiple GAC reactivations on disinfection byproduct precursor removal". Water Supply 4, n.º 4 (1 de diciembre de 2004): 71–78. http://dx.doi.org/10.2166/ws.2004.0063.
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The objective of this study was to compare the adsorption capabilities of the virgin carbon to the twelve and five times reactivated granular activated carbon (GAC). From a water treatment plant operator's perspective, there were very few practical differences in adsorption among the carbons tested for total organic carbon (TOC) and disinfection byproduct (DBP) precursors. However, some overall trends were observed. The GAC that was regenerated 5 times (R5) generally showed greater DBP precursor adsorption than the other GACs especially at the beginning of the runs. In some cases the carbon that was reactivated 12/13 times (R12 and R13) adsorbed slightly less DBP precursors than the other GACs especially in the latter part of the runs. The virgin (V) carbon performed better than the other GACs relative to DBP precursor removal in the latter part of the runs.
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Zaky Sayed, Prof Dr Ahmed. "Adsorptions of Astrazon Dye onto Granular Carbon-Silica Aerogels Synthesized from Recycle Palm-Date Pits: Kinetics, Thermodynamic and Isotherm Studies". JOURNAL OF ADVANCES IN CHEMISTRY 12, n.º 10 (6 de enero de 2017): 4424–39. http://dx.doi.org/10.24297/jac.v12i10.5251.
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In this work, an environmental friendly management process was achieved to solve solid and liquid hazardous contaminants in our environment. In this case, a granular carbon (gAC) sorbent impregnated with SiO2 aerogels as composite (gAC/SiO2) was synthesized from the rceycling of palm-date pits solid waste products to remediate wastewater solution contaminated with Astrazon pink FG cationic dye. The Astrazon dye adsorption onto the gAC/SiO2 was investigated by compared to gAC sorbent alone using a batch system with respect to initial dye concentration, pH, contact time, solution temperature and adsorbents dosage. It was found the amount of adsorbed dye was strongly depended on pH with low significant important of temperatures levels range from 298 to 318 K. The prepared gAC/SiO2 aerogels composite exhibits high efficiency for Astrazon dye adsorption by approximately 1.5 times than that of gAC alone. The equilibrium adsorption states could be achieved in 6 h when using gAC/SiO2 comparable to 12 h by gAC for the different initial dye concentrations. The adsorption kinetics were found to best described by the pseudo-second order model (PSOM) and pseudo-first order (PFOM) kinetic models respectively, when using gAC and gAC/SiO2 sorbents, and poorest-fit with Elvoich equation as confirmed by nonlinear chi-square error test and determination coefficient values. The equilibrium isotherm study indicated that dye adsorption data were analyzed and fitted well by the nonlinear expressions of both Langmuir and Langmuir-Freundlich models compared to Freundlich, Temkin and Redlich–Petersonmodels. The maximum monolayer Astrazon dye adsorption was estimated to be 185.59 and 256.02 µmol/g by gAC and gAC/SiO2 adsorbents. The positive values of the enthalpy (ΔH°) and negative Gibbs free energy (ΔG°) changes indicate an endothermic as well as feasible and spontaneous nature of the adsorption process respectively.
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Shang, Fei, Xiao Lv Zhou, Zhen Xing Zhou, Chen Yan Hu, Jing Zhang y Yi Ming Zhao. "Adsorption Characteristics of L-Phenylalanine in Drinking Water by Granule Activated Carbon". Advanced Materials Research 610-613 (diciembre de 2012): 259–63. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.259.
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In this paper,granular activated carbon GAC was used to investigate the adsorption capacity and adsorption rate of a typical nitrogen-containing organic compounds L-phenylalanine. GAC shows a high adsorption capacity for the L-phenylalanine and the adsorption isotherms conform to with Langmuir model.The pseudo-first-order equation shows the best fitting for adsorption kinetics in L-phenylalanine adsorption by GAC. Besides the factors such as the temperature, adsorption time and activated carbon quantity were studied.
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de Ridder, D. J., A. R. D. Verliefde, S. G. J. Heijman, J. Q. J. C. Verberk, L. C. Rietveld, L. T. J. van der Aa, G. L. Amy y J. C. van Dijk. "Influence of natural organic matter on equilibrium adsorption of neutral and charged pharmaceuticals onto activated carbon". Water Science and Technology 63, n.º 3 (1 de febrero de 2011): 416–23. http://dx.doi.org/10.2166/wst.2011.237.
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Natural organic matter (NOM) can influence pharmaceutical adsorption onto granular activated carbon (GAC) by direct adsorption competition and pore blocking. However, in the literature there is limited information on which of these mechanisms is more important and how this is related to NOM and pharmaceutical properties. Adsorption batch experiments were carried out in ultrapure, waste- and surface water and fresh and NOM preloaded GAC was used. Twenty-one pharmaceuticals were selected with varying hydrophobicity and with neutral, negative or positive charge. The influence of NOM competition and pore blocking could not be separated. However, while reduction in surface area was similar for both preloaded GACs, up to 50% lower pharmaceutical removal was observed on wastewater preloaded GAC. This was attributed to higher hydrophobicity of wastewater NOM, indicating that NOM competition may influence pharmaceutical removal more than pore blocking. Preloaded GAC was negatively charged, which influenced removal of charged pharmaceuticals significantly. At a GAC dose of 6.7 mg/L, negatively charged pharmaceuticals were removed for 0–58%, while removal of positively charged pharmaceuticals was between 32–98%. Charge effects were more pronounced in ultrapure water, as it contained no ions to shield the surface charge. Solutes with higher log D could compete better with NOM, resulting in higher removal.
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Cao, Xiao Qiang, Sheng Rong Liu y Xue Min Huang. "Capture of Toluene Vapors Using Adsorption and Microwave Irradiation Regeneration". Applied Mechanics and Materials 99-100 (septiembre de 2011): 1092–95. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.1092.
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Experimental investigations using granular activated carbon (GAC) adsorption and then desorpted with microwave irradiation for toluene abatement are reported in this paper. The results indicated that the adsorption capacity of GAC for toluene was 198 mg (toluene) / g (GAC) at 303 K. Isotherm analysis of adsorption data obtained at 303 K showed that the adsorption pattern of toluene on GAC followed the Langmuir isotherm. The Langmuir constants Q0 and b were found to be 208.33 mg/g and 0.0023 m3/mg, respectively. At 313 K, the saturated GAC could achieve more than 90% regeneration efficiency in 40 minutes. In this investigation, the reasonable regeneration temperature and superficial gas velocity were 313 K and 0.073 m/s, respectively.
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Tung, Hsin-Hsin, Richard F. Unz y Yuefeng F. Xie. "HAA removal by GAC adsorption". Journal - American Water Works Association 98, n.º 6 (junio de 2006): 107–12. http://dx.doi.org/10.1002/j.1551-8833.2006.tb07687.x.
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Hong, Yong Pyo y Keon Sang Ryoo. "Adsorption Of No3--N And Po43--P in Aqueous Solution Using Granular Activated Charcoal (Gac)". JOURNAL OF ADVANCES IN CHEMISTRY 15, n.º 2 (3 de diciembre de 2018): 6296–305. http://dx.doi.org/10.24297/jac.v15i2.7881.
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In this study, adsorption of NO3- -N and PO43--P on granular activated charcoal (GAC) was investigated depending on pH, agitation time, GAC dosage, adsorption capacity and adsorption isotherms by employing batch adsorption type. The GAC was characterized by thermogravimetric analysis (TG-DTA), scanning electron micrograph coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) and BET surface area analyzer. The GAC exhibited nearly similar adsorption equilibrium time. Both NO3--N and PO43—P appeared to approach equilibrium after approximately 4 h of agitation time. In the adsorption equilibrium, the removal efficiencies of NO3- -N and PO43--P were found to be 14.6-66.0 % and 52.4-99.0 %, respectively. The adsorption data for NO3--N and PO43--P was correlated to Freundlich and Langmuir isotherm model and the equilibrium data was fitted well to the Langmuir isotherm model due to their higher correlation coefficient (R2) value. The Langmuir adsorption capacity was 1.54 and 2.56 mg g-1 for NO3--N and PO43--P, respectively, which suggests that the GAC is a good adsorbent for removal of NO3--N and PO43—P from water.
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Ryoo, Keon Sang, Jong-Ha Choi y Yong Pyo Hong. "Comparison of Adsorptive Removal of Total Nitrogen (T-N) and Total Phosphorous (T-P) in Aqueous Solution using Granular Activated Charcoal (GAC)". JOURNAL OF ADVANCES IN CHEMISTRY 9, n.º 1 (1 de enero de 2013): 1822–36. http://dx.doi.org/10.24297/jac.v9i1.2306.
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The present study is to explore the possibility of utilizing granular activated charcoal (GAC) for the removal of total phosphorous (T-P) and total nitrogen (T-N) in aqueous solution. Batch adsorption studies were carried out to determine the influences of various factors like initial concentration, contact time and temperature. The adsorption data showed that GAC has a similar adsorption capacity for both T-N and T-P. The adsorption degree of T-N and T-P on GAC was highly concentration dependent. It was found that the adsorption capacity of GAC is quite favorable at a low concentration. At concentrations of 1.0 mg L-1 of T-P and 2.0 mg L-1 of T-N, approximately 97 % of adsorption was achieved by GAC. The equilibrium data were fitted well to the Langmuir isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher R2 compared with the pseudo-first-order and intra-particle kinetic model. The theoretical adsorption equilibrium qe,cal from pseudo-second-order kinetic model were relatively similar to the experimental adsorption equilibrium qe,exp. To evaluate the effect of thermodynamic parameters at different temperatures, the change in free energy ΔG, the enthalpy ΔH and the entropy ΔS were estimated. Except for adsorption of T-P at 278 K, the ΔG values obtained were all negative at the investigated temperatures. It indicates that the present adsorption system occurs spontaneously. The adsorption process of T-N by GAC was exothermic in nature, whereas T-P showed endothermic behavior. In addition, the positive values of ΔS imply that there was the increase in the randomness of adsorption of T-N and T-P at GAC-solution interface.
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Moh, H. T., Ivy A. W. Tan y Leonard L. P. Lim. "Removal of Atrazine from Water Using Oil Palm Shell Based Adsorbents: Equilibrium and Kinetic Study". Journal of Civil Engineering, Science and Technology 4, n.º 2 (1 de octubre de 2013): 18–23. http://dx.doi.org/10.33736/jcest.114.2013.
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Adsorption using granular activated carbon (GAC) in a permeable reactive barrier (PRB) has been proven in inhibiting the further spread of contaminant plumes in groundwater. GAC synthesized from oil palm shell was chosen for groundwater remediation in this study due to the low operation cost using the adsorption process. In this study, GAC synthesized from oil palm shells were used as adsorbent to adsorb atrazine from water. This study involved a series of batch experiment to determine the adsorption equilibrium and kinetics of adsorbent. The batch experiment was conducted by shaking conical flasks containing 0.6 g GAC in 300 mL solution with initial atrazine concentrations of 5, 10, 20 and 30 mg/L at 180 rpm at 30 ± 2 °C. The GAC showed more than 95 % of atrazine removal in all the batch experiments. The adsorption kinetic study showed that the adsorption of atrazine is of physisorption as the experimental data is fitted better to the pseudo-first-order model than the pseudo- second-ordermodel.Intheadsorptionisothermstudy,theadsorptionofatrazineontoGACwasbetterdescribedbytheFreundlich model which indicated multilayer adsorption on the heterogeneous surface of the adsorbent. The atrazine adsorption capacity of the GAC was 15.132 mg/g, which was higher than that using the activated carbon synthesized from waste charcoal (13.947 mg/g). ThisstudyshowsthatthereisapotentialforGACtobeusedforremediatinggroundwatercontaminatedbypesticides.
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Choi, Hyun Soo y Dong Seok Rhee. "Catalytic Ozonation with Activated Carbon for Treatment of Humic Substances in Water". Applied Mechanics and Materials 470 (diciembre de 2013): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amm.470.19.
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Ozonation of the ubiquitous and poorly biodegradable humic acid in aquatic system was conducted in the presence of activated carbon with the aim of catalyst. The optimum operating parameters deduced from this study was GAC amount of 16.5 v/v% (GAC column volume per reactor volume) in the humic acid solution of initial pH 9. DOC removal rate in Ozone/GAC process was higher than the sum of Ozone alone and GAC adsorption process. Formaldehyde formation in Ozone/GAC process was less than in Ozone alone and GAC adsorption process. The part of molecular size distribution under 10 k Dalton were increased in the Ozone/GAC process.
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Hatt, J. W., E. Germain y S. J. Judd. "Granular activated carbon for removal of organic matter and turbidity from secondary wastewater". Water Science and Technology 67, n.º 4 (1 de febrero de 2013): 846–53. http://dx.doi.org/10.2166/wst.2012.644.
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A range of commercial granular activated carbon (GAC) media have been assessed as pretreatment technologies for a downstream microfiltration (MF) process. Media were assessed on the basis of reduction in both organic matter and turbidity, since these are known to cause fouling in MF membranes. Isotherm adsorption analysis through jar testing with supplementary column trials revealed a wide variation between the different adsorbent materials with regard to organics removal and adsorption kinetics. Comparison with previous work using powdered activated carbon (PAC) revealed that for organic removal above 60% the use of GAC media incurs a significantly lower carbon usage rate than PAC. All GACs tested achieved a minimum of 80% turbidity removal. This combination of turbidity and organic removal suggests that GAC would be expected to provide a significant reduction in fouling of a downstream MF process with improved product water quality.
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Zhang, Feng, Dong-Sheng Wang, Fan Yang, Tian-Yu Li, Hong-Yan Li y Jian-Guo Cui. "Effect of Sodium Benzenesulfonate on SO42− Removal from Water by Polypyrrole-Modified Activated Carbon". Advances in Materials Science and Engineering 2021 (23 de septiembre de 2021): 1–13. http://dx.doi.org/10.1155/2021/1442506.
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Sodium benzenesulfonate was doped into polypyrrole-modified granular activated carbon (pyrrole-FeCl3·(6H2O)-sodium benzenesulfonate-granular activated carbon; PFB-GAC) with the goal of improving the modified GAC’s ability to adsorb sulfate from aqueous solutions. At a GAC dosage of 2.5 g and a pyrrole concentration of 1 mol L−1, the adsorption capacity of PFB-GAC prepared using a pyrrole:FeCl3·(6H2O):sodium benzenesulfonate ratio of 1000 : 1500 : 1 reached 23.05 mg g−1, which was eight times higher than that for GAC and two times higher than that for polypyrrole-modified GAC without sodium benzenesulfonate. Adsorption was favored under acidic conditions and high initial sulfate concentrations. Doping with sodium benzenesulfonate facilitated polymerization to give polypyrrole. Sodium benzenesulfonate introduced more imino groups to the polypyrrole coating, and the N+ sites improved ion exchange of Cl− and SO42− and increased the adsorption capacity of sulfate. Adsorption to the PFB-GAC followed pseudo-second-order kinetics. The adsorption isotherm conformed to the Langmuir model, and adsorption was exothermic. Regeneration using a weak alkali (NH3·H2O), which released OH− slowly, caused less damage to the polypyrrole than using a strong alkali (NaOH) as the regeneration reagent. NH3·H2O at a concentration of 12 mol L−1 (with the same OH− concentration as 2 mol L−1 NaOH) released 85% of the sorbed sulfate in the first adsorption-desorption cycle, and the adsorption capacity remained >6 mg g−1after five adsorption-desorption cycles.
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Ali, Rehab M., Mohamed A. Hassaan y Marwa R. Elkatory. "Towards Potential Removal of Malachite Green from Wastewater: Adsorption Process Optimization and Prediction". Materials Science Forum 1008 (agosto de 2020): 213–21. http://dx.doi.org/10.4028/www.scientific.net/msf.1008.213.
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Granular activated carbon (GAC) is utilized as an adsorbent for the malachite green (MG) dye removal from aqueous solutions. The GAC was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) to realize the GAC chemical and physical features effects on the adsorption efficiency. Batch adsorption processes were carried out with different variables like pH, GAC dose, initial MG concentration and time. The response surface methodology (RSM) was used to design the experiments, model the adsorption process, optimize the operating conditions and predict the response. A 24 full factorial central composite design (CCD) was performed for the experimental design and the analysis of the results. Analysis of variance (ANOVA) was employed to determine the significance of the factors and explore the interaction between the various experimental parameters. An empirical model was derived to correlate the experimental results and predict the behavior of the GAC for the adsorption process. The model showed a good agreement with the experimental results of R2 = 0.9968 and evidenced that the optimum operating parameters are pH 10, 2 g GAC/L, 200 mg/L of MG initial concentration and 113 min adsorption time for complete removal of MG.
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Jamaliniya, Sara, O. D. Basu, Saumya Suresh, Eustina Musvoto y Alexis Mackintosh. "Kinetic analysis of sucrose activated carbon for nutrient removal in water". H2Open Journal 3, n.º 1 (1 de enero de 2020): 208–20. http://dx.doi.org/10.2166/h2oj.2020.012.
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Abstract A renewable, green activated carbon made from sucrose (sugar) was compared with traditional bituminous coal-based granular activated carbon (GAC). Single and multi-component competitive adsorption of nitrate and phosphate from water was investigated. Langmuir and Freundlich isotherm models were fitted to data obtained from the nitrate and phosphate adsorption experiments. Nitrate adsorption fits closely to either Freundlich or Langmuir model for sucrose activated carbon (SAC) and GAC with a Langmuir adsorption capacity of 7.98 and 6.38 mg/g, respectively. However, phosphate adsorption on SAC and GAC demonstrated a selective fit with the Langmuir model with an adsorption capacity of 1.71 and 2.07 mg/g, respectively. Kinetic analysis demonstrated that adsorption of nitrate and phosphate follow pseudo-second-order kinetics with rate constant values of 0.061 and 0.063 g/(mg h), respectively. Competitive studies between nitrate and phosphate were demonstrated in preferential nitrate removal with GAC and preferential phosphate removal with SAC. Furthermore, nitrate and phosphate removals decreased from 75% removal to 35% removal when subject to multi-component solutions, which highlights the need for adsorption analysis in complex systems. Overall, SAC proved to be competitive with GAC in the removal of inorganic contaminants and may represent a green alternative to coal-based activated carbon.
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Prateek, Chandrakant Thakur, Vimal Chandra Srivastava y Indra Deo Mall. "Comparative Studies on Nitrophenol Removal byAdsorption and Simultaneous Adsorption-Biodegradation Processes". ijcre 11, n.º 1 (19 de diciembre de 2013): 595–607. http://dx.doi.org/10.1515/ijcre-2013-0088.
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Abstract In this paper, it was aimed to study the removal of 4-nitrophenol (NP) from aqueous solution by adsorption using granular activated carbon (GAC); and in sequencing batch reactor (SBR) without any adsorbent (blank-SBR) and with an SBR loaded with GAC (GAC–SBR). During adsorption study with GAC, effect of pH, adsorbent dose (m) and contact time (t) were studied. Adsorption isotherm, kinetic and thermodynamic parameters were determined. During NP removal in SBR, effect of hydraulic retention time (HRT), initial concentration (C 0) and m were studied. The percent removal in case of GAC–SBR was found to be greater in comparison to blank-SBR. The removal of NP from blank-SBR and GAC–SBR for C 0 of 35, 65 and 100 mg/l was found to be 90.46% and 91.23% (m=2 g/l); 52.33% and 96.05% (m=2.5 g/l); 20.01% and 92.72% (m=2.5 g/l), respectively.
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Vidic, R. D. y M. T. Suidan. "Effect of Dissolved Oxygen on Phenols Breakthrough from GAC Adsorbers". Water Science and Technology 26, n.º 5-6 (1 de septiembre de 1992): 1185–93. http://dx.doi.org/10.2166/wst.1992.0560.
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This study demonstrates that molecular oxygen plays an important role in the adsorption of organic compounds from water by activated carbon. It was determined that the adsorptive capacity of granular activated carbon (GAC) for o-cresol can increase by almost 200% as a result of the presence of molecular oxygen in the test environment (oxic conditions). This increase in adsorptive capacity is not due to biological activity but can be totally attributed to the polymerization of o-cresol on the carbon surface under oxic conditions. The rate of adsorbate polymerization is such that the presence of molecular oxygen does not influence adsorption kinetics during the first 12 hours of adsorbent-adsorbate contact. However, the concentration of dissolved oxygen in the feed to a GAC adsorber can significantly influence the breakthrough of adsorbate. As the concentration of dissolved oxygen increased, more of this increased capacity is utilized during the early phase of breakthrough and, consequently, initial breakthrough is delayed. This phenomenon might completely change the existing procedures for the design and operation of GAC adsorbers in that it provides a competitive edge for adsorption as a treatment technology in water purification.
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VanderLoop, Sarah L., Makram T. Suidan, Sandra R. Berchtold, Moustafa A. Moteleb y Stephen W. Maloney. "Effects of molecular oxygen on GAC adsorption of energetics". Water Science and Technology 35, n.º 7 (1 de abril de 1997): 197–204. http://dx.doi.org/10.2166/wst.1997.0277.
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Munitions wastewaters are commonly treated by granular activated carbon (GAC) adsorption followed by incineration of the spent carbon. The design of effective GAC unit processes hinges on the knowledge of GAC adsorption capacity for the compounds of interest as well as the types of chemical interactions to expect. GAC can often catalyze polymerization or chemical degradation of the adsorbate in the presence of molecular oxygen. Some adsorbates, though less common, may be subject to catalytic activity even when no molecular oxygen is present. The products of these interactions may enhance or interfere with effective waste treatment. This study individually evaluated the adsorption properties of a variety of energetics compounds. A number of surface catalyzed polymerization and degradation reactions were noted.
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Luekittisup, Prapaporn, Visanu Tanboonchauy, Jitlada Chumee, Somrudee Predapitakkun, Rattanawan W. Kiatkomol y Nurak Grisdanurak. "Removal of Chlorinated Chemicals in H2Feedstock Using Modified Activated Carbon". Journal of Chemistry 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/959012.
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Activated carbon (GAC) was impregnated by sodium and used as adsorbent to remove chlorinated hydrocarbon (CHC) gases contaminated in H2feedstock. The adsorption was carried out in a continuous packed-bed column under the weight hourly space velocity range of 0.8–1.0 hr−1. The adsorption capacity was evaluated via the breakthrough curves. This modified GAC potentially adsorbed HCl and VCM of 0.0681 gHCl/gadsorbentand 0.0026 gVCM/gadsorbent, respectively. It showed higher adsorption capacity than SiO2and Al2O3balls for both organic and inorganic CHCs removal. In addition, the kinetic adsorption of chlorinated hydrocarbons on modified GAC fit well with Yoon-Nelson model.
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Yao, Yuan, Konstantin Volchek, Carl E. Brown, Adam Robinson y Terry Obal. "Comparative study on adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) by different adsorbents in water". Water Science and Technology 70, n.º 12 (8 de noviembre de 2014): 1983–91. http://dx.doi.org/10.2166/wst.2014.445.
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Perfluorinated compounds (PFCs) are emerging environmental pollutants. Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are the two primary PFC contaminants that are widely found in water, particularly in groundwater. This study compared the adsorption behaviors of PFOS and PFOA on several commercially available adsorbents in water. The tested adsorbents include granular activated carbon (GAC: Filtrasorb 400), powdered activated carbon, multi-walled carbon nanotube (MCN), double-walled carbon nanotube, anion-exchange resin (AER: IRA67), non-ion-exchange polymer, alumina, and silica. The study demonstrated that adsorption is an effective technique for the removal of PFOS/PFOA from aqueous solutions. The kinetic tests showed that the adsorption onto AER reaches equilibrium rapidly (2 h), while it takes approximately 4 and 24 h to reach equilibrium for MCN and GAC, respectively. In terms of adsorption capacity, AER and GAC were identified as the most effective adsorbents to remove PFOS/PFOA from water. Furthermore, MCN, AER, and GAC proved to have high PFOS/PFOA removal efficiencies (≥98%). AER (IRA67) and GAC (Filtrasorb 400) were thus identified as the most promising adsorbents for treating PFOS/PFOA-contaminated groundwater at mg L−1 level based on their equilibrium times, adsorption capacities, removal efficiencies, and associated costs.
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Zhao, Chuan Bao, Dong Mei Shi, Bo Tao Lin y Yan Qiang Jia. "Preparation and Characterization of TiO2/Coconut-Activated Carbon Photocatalytic Materials". Advanced Materials Research 1015 (agosto de 2014): 667–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1015.667.
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Using Ti (OC4H9)4 as the precursor,and GAC as carrier, making use of technology of hydrolyzation and natural assembling,TiO2/GAC composite material was preparated at the lower temperature.The characterization of obtained TiO2 /Coconut-Activated Carbon’scrystal structure and appearance by XRD and SEM.The adsorption capacity and photocatalytic performance on phenol were measured.Results show that TiO2/GAC surface was well-distributed and remains a little interspace.A nanocrystal TiO2 aerogel size is without 30nm.The sample shows lower adsorption compared to GAC.But photocatalytic efficiency was higher than GAC under the exposure of the sunlight or the violet.
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Liu, X. y C. S. B. Fitzpatrick. "Removal of humic substances using solar irradiation followed by granular activated carbon adsorption". Water Supply 10, n.º 1 (1 de marzo de 2010): 15–22. http://dx.doi.org/10.2166/ws.2010.003.
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This study proposed a new method using freely available sunlight and granular activated carbon (GAC) adsorption for enhanced removal of humic substances (HS). Experiments were carried out under natural sunlight conditions in winter and summer. A parabolic solar collector (PC) was applied to concentrate solar energy. HS were characterized by UV254 absorbance, dissolved organic carbon (DOC) concentration and molecular weight (MW). As a result of solar irradiation, decreases of DOC up to 14% in winter and 58% in summer were observed. A comparison of adsorption isotherms and chromatograms of the irradiated and non-irradiated HS confirmed that smaller molecules formed during solar irradiation were preferentially adsorbed by GAC. A dramatic MW change upon solar irradiation was observed in HS irradiation in PC in summer experiment and almost no UV254 detected components were remaining in solution after adsorption (GAC dose 400 mg/L), as measured with high performance size exclusion chromatography (HPSEC). The combined solar irradiation-GAC adsorption method proved to be effective in enhancing HS removal by GAC with no additional energy and chemicals consumption.
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Matsui, Yoshihiko, Tasuku Kamei, Etsuro Kawase, Vernon L. Snoeyink y Norihito Tambo. "GAC adsorption of intermittently loaded pesticides". Journal - American Water Works Association 86, n.º 9 (septiembre de 1994): 91–102. http://dx.doi.org/10.1002/j.1551-8833.1994.tb06249.x.
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Krupa, Nicholas E. y Fred S. Cannon. "GAC: pore structure versus dye adsorption". Journal - American Water Works Association 88, n.º 6 (junio de 1996): 94–108. http://dx.doi.org/10.1002/j.1551-8833.1996.tb06574.x.
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Vinitnantharat, S., W. Rattanasirisophon y Y. Ishibashi. "Modification of granular activated carbon surface by chitosan coating for geosmin removal: sorption performances". Water Science and Technology 55, n.º 5 (1 de marzo de 2007): 145–52. http://dx.doi.org/10.2166/wst.2007.173.
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This study presents the results of the sorption performances for geosmin removal by sorption onto granular activated carbons (GAC) manufactured from different raw materials of coconut shell and bituminous coal. The surface of GAC was modified by chitosan coating. The 90% deacetylated chitosan flakes were used for coating on GAC with the GAC: chitosan ratio of 5:1. The surface of GAC was characterised by scanning electron microscope (SEM) analysis, Fourier transform infrared spectroscopy and measurement of the pH solution of GAC samples. The sorption of geosmin onto the chitosan for both uncoated and coated GACs could be described by the Freundlich adsorption model. Data revealed that the sequence of Freundlich constant (KF) was chitosan coated bitominous coal (CB) > uncoated bituminous coal (UB) > chitosan coated coconut shell (CC) ≅ uncoated coconut shell (UC). The bituminous coal based GAC with chitosan coating had a maximum capacity of 23.57 μg/g which was approximately two-fold of uncoated bituminous coal based GAC. Two simplified kinetic models, pseudo-first order and pseudo-second order, were tested to investigate the sorption mechanisms. It was found that the intraparticle diffusion was a rate controlling step for the sorption and followed the pseudo-second order equation.
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Oh, S. Y., D. K. Cha, P. C. Chiu y B. J. Kim. "Conceptual comparison of pink water treatment technologies: granular activated carbon, anaerobic fluidized bed, and zero-valent iron-Fenton process". Water Science and Technology 49, n.º 5-6 (1 de marzo de 2004): 129–36. http://dx.doi.org/10.2166/wst.2004.0746.
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Pink water, explosive-laden wastewater produced in army ammunition plants is often treated using expensive and non-destructive granular activated carbon (GAC) adsorption. This paper compares GAC adsorption and two alternative treatment technologies, anaerobic GAC fluidized bed reactor and zero-valent iron-Fenton process. The bench-scale demonstration of the zero-valent iron-Fenton process with real pink water is reported. The features of three technologies are compared and their advantages and drawbacks are discussed.
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Wu, Dao Ji, Cheng Long Lv, Zhao Liang Zhu, Ning Wang, Shu Jie Li y Hao Li. "Study on Indicators for Granular Activated Carbon Screening and Adsorption Cycle Determining". Advanced Materials Research 1092-1093 (marzo de 2015): 1006–12. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.1006.
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Four kinds of granular activated carbon GAC were treated by water taken from surface drinking-water sources in Ji’nan. Five adsorption performance indicators of granular activated carbon (GAC) were investigated. The correlation between the indicators and the removal rate of organic matter in raw water was analysed and the results showed that the removal rates of CODMn and DOC were well correlated with iodine value, the coefficient correlations, R2 were 0.8745 and 0.8474 respectively, the removal rates of UV254 was well correlated with methylene blue value (R2 = 0.9454), indicating the capability as indicator for GAC selection. Additionally, one original GAC was used to adsorb organic matter in raw water, as well as the GAC samples treated with four different saturation time in raw water, to investigate the residue rate of adsorption ability. Of all five adsorption performance indicators, it was found that the iodine value, methylene blue value, and tannic acid were negatively related to the residual rate of the GAC absorption ability (R2 was over 0.9). Based on the research, the activated carbon filters in Quehua Water plant in Ji’nan was evaluated and the replacement of them was suggested.
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Sorial, George A., Makram T. Suidan, Radisav D. Vidic y Stephen W. Maloney. "Competitive Adsorption of Phenols on GAC. I: Adsorption Equilibrium". Journal of Environmental Engineering 119, n.º 6 (noviembre de 1993): 1026–43. http://dx.doi.org/10.1061/(asce)0733-9372(1993)119:6(1026).
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Liu, Bao Jian, Shi Wang Liu, Tie Bing Liu y Jian Wei Mao. "A Novel Granular Activated Carbon Adsorption Method for Separation of Levulinic Acid from Formic Acid". Advanced Materials Research 550-553 (julio de 2012): 1691–95. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1691.
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Levulinic acid (LA) is a new versatile platform chemical derived from renewable non-food biomass. A major challenge in the purification of LA from biomass hydrolysate is the separation of LA and formic acid. A novel granular activated carbon (GAC) adsorption and separation of LA and formic acid were investigated in this work. Adsorption equilibria elucidated that LA preferentially adsorbed onto GAC than formic acid. Mixed solution of LA and formic acid was fed into the GAC packed-bed at 30°C, then formic acid was washed out from the column in a pure form with 60°C water and finally LA was effectively eluted with 95% (v/v) ethanol at 60°C. LA can be completely separated from formic acid by this simple GAC adsorption process with good yield and high purity.
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Choe, Hyun-Seok, Ki Yong Kim, Jeong-Eun Oh y Jae-Hyuk Kim. "Parallel study on removal efficiency of pharmaceuticals and PFASs in advanced water treatment processes: Ozonation, GAC adsorption, and RO processes". Environmental Engineering Research 27, n.º 1 (20 de diciembre de 2020): 200509–0. http://dx.doi.org/10.4491/eer.2020.509.
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We aimed to assess the removal efficiencies of four pharmaceuticals (carbamazepine, crotamiton, metformin, and sulfamethoxazole) and four poly- and perfluoroalkyl substances (PFASs) (PFHxA, PFHxS, PFOA, and PFOS) by lab-scale ozonation, granular activated carbon (GAC) adsorption, and reverse osmosis (RO) membrane processes under varying operating conditions. Ozonation and GAC adsorption processes were conducted at two temperatures (5 and 25°C) and three pH conditions (3, 7, and 11). The membrane process was performed using an unstirred cell with two different RO membranes. The most pharmaceuticals were effectively removed by ozonation, whereas metformin and PFASs were unaffected due to their stable chemical structures. In the GAC process, metformin was hardly removed under acidic conditions but it was enhanced by over 90%. PFASs were effectively removed by GAC adsorption and RO membrane processes. The RO membrane for brackish water treatment showed higher rejection than that for residential water treatment. Moreover, the rejection of PFAS increased as the molecular weight increased. A strategy was found to effectively remove the remaining metformin in most advanced water treatment processes. Chemically persistent PFASs were hardly removed by the ozonation process but were effectively removed by physical treatments such as GAC adsorption and RO membrane processes.
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Fu, Yi, Luo Chun Wang y Zhen Zhou. "Microwave Regeneration of Field-Spent Granular Activated Carbon from Power Plants". Advanced Materials Research 356-360 (octubre de 2011): 2065–70. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.2065.
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Granular activated carbon (GAC) is extensively used to remove natural organic matter and residential chlorine in water treatment process of power plant. After being used, the spent GAC needs to be regenerated in order to save on operation costs and reduce solid waste disposal. In this study, microwave technique was tried to regenerate the field-spent GAC from a power plant. The effect of microwave power, irradiation time and hydrochloric acid pretreatment were investigated, it was found that microwave could recover the adsorption capacity of GAC within a short time and the tannic acid adsorption efficiency of regenerated GAC was 9 times greater than spent GAC; hydrochloric acid pretreatment could improve the regeneration process, it showed the highest removal efficiency and iodine number, 99.6% and 859 mg/g respectively. The results obtained from SEM-EDX showed that hydrochloric acid pretreatment could remove inorganic matter and other impurities of GAC. All these indicate that microwave technique can effectively regenerate field-spent GAC, and hydrochloric acid pretreatment is an important process before regeneration.
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Tian, Kaixun, Jing Xiao, Jian Shen y He Zhao. "Tailoring electronic configurations in adsorptive sites for the enhancement of As(V) removal from groundwater". Water Supply 20, n.º 3 (30 de diciembre de 2019): 828–36. http://dx.doi.org/10.2166/ws.2019.197.
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Abstract In the past few decades, heavy metal pollution, such as As(V), has become an important issue for aqueous environment safety. For reasons of practical feasibility and cost-effectiveness, adsorption has been widely used in the water treatment and reuse community, with rapid development of adsorbents. However, the precise control of the electronic configuration of the adsorbents' sites to enhance adsorption performance is largely unexplored. In this study, to demonstrate the effect of electronic configuration on adsorption performance, we synthesized granular activated carbon (GAC) supported Fe-based hydroxides adsorbents by varying the valence state in transition metals. Furthermore, the adsorbents are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) to identify surface structure and morphological properties. Adsorptive performance studies show that the adsorption capacity and arsenic removal efficiency of Fe(II)-GAC are twice those of Fe(III)-GAC, as a matter of charge transfer between adsorbents and cationic pollution (such as Fe-O and As species). Finally, PO43− was selected as a control sample to confirm the rationality of the removal mechanism. Collectively, fine-tuning of the electronic configuration from charge transfer will not only benefit heavy metal removal channels, but also supply fundamental information for adsorbents design for organics removal.
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Lu, Q. y G. Sorial. "Impact of pore size on competitive adsorption of phenolic compounds". Water Supply 4, n.º 5-6 (1 de diciembre de 2004): 1–7. http://dx.doi.org/10.2166/ws.2004.0086.
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Single and binary solute adsorption of phenol and o-cresol at 23°C on three activated carbons with different pore size were conducted in this study. One granular activated carbon (GAC) F400 and two activated carbon fibers (ACFs) were considered. Anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions were evaluated. For the single solute system, the three adsorbents studied have shown higher adsorptive capacities under oxic conditions as compared to anoxic conditions. The degree of adsorption enhancement was related to the pore size of the adsorbent. For binary adsorption on ACC-10, which has the least average pore size (1.76 nm), the oxic and anoxic adsorption isotherms overlapped, indicating no impact of the presence of molecular oxygen on the adsorptive capacity. Significant differences on adsorptive capacities were noticed for the binary solute adsorption on ACC-15 (2.10 nm) and F400 (2.48 nm). The Ideal Adsorbed Solution Theory (IAST) predicted well all binary systems for ACC-10 and anoxic isotherms on ACC-15 and F400. Poor model predictions for GAC and ACC-15 under oxic conditions were attributed to the oligomerization of the adsorbates on the surface of activated carbon. The unique pore size of ACFs has been shown to be a limiting factor in hampering the oligomerization under oxic conditions.
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Doederer, K., G. A. De Vera, M. P. Espino, M. L. Pype, D. Gale y J. Keller. "MIB and geosmin removal during adsorption and biodegradation phases of GAC filtration". Water Supply 18, n.º 4 (25 de octubre de 2017): 1449–55. http://dx.doi.org/10.2166/ws.2017.213.
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Abstract Biologically active carbon (BAC) filtration is a robust process for removal of many contaminants of concern. In this study, the effectiveness of BAC filtration to remove natural organic matter (NOM) and taste and odor (T&O) compounds was investigated by long-term (7 months) bench-scale filtration experiments. Filters contained fresh granular activated carbon (GAC) and a 2-year-old BAC which were fed with ozonated water from a full-scale water treatment plant spiked with 2-methylisoborneol (MIB) and geosmin. The study aims to evaluate T&O removal of GAC transitioning from its adsorptive to biological state, and to determine the effects of changing hydraulic loading during T&O episodes and its effect on dissolved oxygen (DO) consumption. Sequencing of microbial communities in the BAC revealed that 20% of the identified bacteria were of genus Nitrospira. Based on nitrate formation and dissolved organic carbon (DOC) removal of the 2-year-old BAC, the fresh GAC turned biological after approximately 32,000 bed volumes. DOC removal of the GAC decreased from the initial 80% to 17%, however, the removal of MIB and geosmin remained >90% throughout the experiment (i.e., from adsorption to biodegradation). The 2-year-old BAC showed 9% lower MIB removals than the transitioned GAC filter indicating a contribution of remaining adsorption sites on MIB removal. When challenging the filters at different hydraulic loadings, higher T&O removal was achieved at higher empty bed contact times, which correlated well with increased DO consumption.
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Tsuno, H., M. Kawamura y T. Oya. "Application of biological activated carbon anaerobic reactor for treatment of hazardous chemicals". Water Science and Technology 53, n.º 11 (1 de mayo de 2006): 251–60. http://dx.doi.org/10.2166/wst.2006.360.
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An expanded-bed anaerobic reactor with granular activated carbon (GAC) medium has been developed to treat wastewaters that contain a high concentration of inhibitory and/or refractory organic compounds as well as readily degradable organic compounds. The process is characterised by a combination of two removal mechanisms; adsorption on GAC and biological degradation by microorganisms grown on GAC. Applicability of the reactor to treatment of phenol, chloroacetaldehyde (CAA), pentachlorophenol (PCP) and tetrachloroethylene (PCE) was discussed based on experimental data. All chemicals focused on here were removed well and stably at a removal efficiency of more than 98% even during starting operation and shock load operation. Chemicals in influent that exceeded biological degradation capacity was initially adsorbed on GAC and then gradually degraded, and hence the adsorptive capacity of GAC was regenerated biologically. These results proved that a biological activated carbon anaerobic reactor was effective for treatment of wastewater containing hazardous chemicals, especially for strongly absorbable chemicals, as well as readily degradable organic compounds at high concentration.
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Liu, Charlie J., David Werner y Christopher Bellona. "Removal of per- and polyfluoroalkyl substances (PFASs) from contaminated groundwater using granular activated carbon: a pilot-scale study with breakthrough modeling". Environmental Science: Water Research & Technology 5, n.º 11 (2019): 1844–53. http://dx.doi.org/10.1039/c9ew00349e.
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HUMPOLA, PABLO D., HECTOR S. ODETTI, ETHEL S. E. FLORES y JOSE LUIS VICENTE. "DESCRIPTION OF DIFFERENT SOLID ADSORBENT SURFACES ADSORPTION MECHANISMS BASED ON A SEQUENTIAL DECOMPOSITION OF ISOTHERMS". Surface Review and Letters 20, n.º 02 (abril de 2013): 1350022. http://dx.doi.org/10.1142/s0218625x13500224.
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In order to analyze the adsorption capacities of different solid substrates, we present a multi-step method to separately study the isotherm at different pressure ranges (steps). The method is based on simple gas isotherm measurements (nitrogen, methane, carbon dioxide, argon, and oxygen) and is tested to describe the adsorption process and characterize a graphitized surface (GCB) and two different granular activated carbons (GAC). The GCB isotherms are described as a sum of Fowler-Guggenheim-Langmuir shifted curves; isotherm behaviors are quite similar at different temperatures, but change below a certain threshold. In GAC the first steps show the same adsorption characteristics at low pressures (Dubinin's description), but this behavior changes at higher pressure regimes, which allows one to elucidate how heterogeneous the surfaces are or how strong the interactions between adsorbed molecules are for this marginal adsorption to occur. We tested different approaches (from BET multilayer to Aranovich) and found quite different features. We finally conclude that if the description of the adsorption on complex substrates, such as those presented here, is carried using only one model, e. g. Dubinin in case of GACs, the resulting characteristics of the adsorbent would be very biased.
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Okonji, Stanley Onyinye, Linlong Yu, John Albino Dominic, David Pernitsky y Gopal Achari. "Adsorption by Granular Activated Carbon and Nano Zerovalent Iron from Wastewater: A Study on Removal of Selenomethionine and Selenocysteine". Water 13, n.º 1 (25 de diciembre de 2020): 23. http://dx.doi.org/10.3390/w13010023.
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Selenomethionine (SeMet) and selenocysteine (SeCys) are the most common forms of organic selenium, which is often found in the effluent of industrial wastewater. These organic selenium compounds are toxic, bioavailable and most likely to bioaccumulate in aquatic organisms. This study investigated the use of two adsorbent candidates (granular activated carbon (GAC) and nano zerovalent iron (nZVI)) as treatment technologies for SeMet and SeCys removal. Batch experiments were performed and inductively coupled plasma optical emission spectrometer (ICP-OES) was used for sample analysis. Experimental data showed GAC demonstrated a higher affinity towards the removal of SeMet and SeCys compared to nZVI. The removal efficiency of SeCys and SeMet by GAC was 96.1% and 86.7%, respectively. NZVI adsorption capacity for SeCys was 39.4% and SeMet < 1.1%. Irrespective of the adsorbent, SeMet is more refractory to be adsorbed compared to SeCys. Kinetics data of GAC and nZVI agreed well with the pseudo-second-order model (R2 > 0.990). The experimental data of SeCys was characterized by Langmuir model, indicating monolayer adsorption. The adsorption capacity of nZVI for SeCys increased significantly by about 35%, with a decrease in pH from 9.0 to 4.0, indicating that SeCy removal by nZVI is pH dependent. While electrostatic attraction is considered the driving mechanism for nZVI adsorption, GAC uptake capacity is controlled by weak van der Waal forces. The adsorption of binary adsorbates (SeMet and SeCys) exhibited an inhibitory effect due to the competitive interaction between contaminant molecules.