Relevant bibliographies by topics / CMC-nZVI

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Academic literature on the topic 'CMC-nZVI'

Author: Grafiati
Published: 4 June 2021
Last updated: 13 February 2022

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Journal articles on the topic "CMC-nZVI"

1

Ibrahim, Hesham M., Mohammed Awad, Abdullah S. Al-Farraj, and Ali M. Al-Turki. "Stability and Dynamic Aggregation of Bare and Stabilized Zero-Valent Iron Nanoparticles under Variable Solution Chemistry." Nanomaterials 10, no. 2 (January 22, 2020): 192. http://dx.doi.org/10.3390/nano10020192.

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Surface modification of nanoscale zero-valent iron (nZVI) using polymer stabilizers (e.g., sodium carboxymethyl cellulose, CMC) is usually used to minimize aggregation, increase stability, and enhance transport of nZVI. We investigated the stability and dynamic aggregation of bare and CMC–nZVI as affected by variations in pH, ionic strength (IS), and nZVI particle concentration. CMC coating of nZVI resulted in smaller hydrodynamic size and larger zeta potential. The largest hydrodynamic size of nZVI was associated with bare nZVI at high IS (100 mM), pH close to the point of zero charge (PZC, 7.3–7.6), and larger particle concentration (1.0 g L−1). The increase in the zeta potential of CMC–nZVI reached one- to four-fold of that for bare nZVI, and was greater at pH values close to PZC, high IS, and larger particle concentration. The stability of CMC–nZVI was increased by 61.8, 93.1, and 57.5% as compared to that of bare nZVI at IS of 1, 50 and 100 mM, respectively. Calculations of Derjaguin, Landau, Verwey and Overbeek (DLVO) interaction energy were in agreement with stability results, and showed the formation of substantial energy barriers at low IS indicating greater nZVI stability. Our results suggest that at IS above 50 mM and nZVI particle concentration larger than 0.1 g L−1, the likelihood of nZVI aggregation is high. Nevertheless, CMC polymer stabilizer would enhance the stability and transport of nZVI even under these unfavorable solution chemistry conditions.
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Ayob, Afizah, Salina Alias, Farrah Aini Dahalan, Ragunathan Santiagoo, Ahmad Zuhairi Abdullah, and Tjoon Tow Teng. "Kinetic removal of Cr6+ by carboxymethyl cellulose-stabilized nano zerovalent iron particles." Macedonian Journal of Chemistry and Chemical Engineering 34, no. 2 (November 12, 2015): 295. http://dx.doi.org/10.20450/mjcce.2015.523.

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Carboxymethyl cellulose (CMC) was used in the chemical reduction method for producing dispersible nano zerovalent iron (nZVI) particles served as reactive, mobile and convenient adsorbent. CMC-stablized nZVI particles at CMC:Fe2+ = 0.0034 molar ratio were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy assisted with probe ultrasonication dispersing tool. FTIR depicted that the CMC monomers were adsorbed onto nZVI particles primarily through carbonyl head groups via monodentate bonding. The botryoidally clusters were the predominant morphology of CMC-stablized nZVI particles under SEM observation. Those spherical particles were evenly dispersed at sizes less than 100 nm under TEM analysis. nZVI particles stabilization with CMC (at CMC:Fe2+ molar ratio of 0.0050) prevented the aggregation and resulted in high catalytic reactivity observed at pseudo-first order constant value, K1 of 0.0196 min-1 for Cr6+ removal in contaminated aqueous. This study demonstrates that CMC-stablized nZVI particles has the potential to become an effective agent for in-situ subsurface environment remediation.
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Zhang, Runyuan, Nuanqin Zhang, and Zhanqiang Fang. "In situ remediation of hexavalent chromium contaminated soil by CMC-stabilized nanoscale zero-valent iron composited with biochar." Water Science and Technology 77, no. 6 (February 1, 2018): 1622–31. http://dx.doi.org/10.2166/wst.2018.039.

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Abstract In this study, the remediation experiments were performed outdoors in natural conditions. Carboxymethyl cellulose (CMC)-stabilized nanoscale zero-valent iron (CMC-nZVI), biochar (BC) and CMC-stabilized nanoscale zero-valent iron composited with biochar (CMC-nZVI/BC) were synthesized and investigated for their effect on the in situ remediation of hexavalent chromium [Cr(VI)] contaminated soil and the concentration of available iron was tested after the remediation, compared with the untreated soil. The results of toxicity characteristic leaching procedure (TCLP) test showed that CMC-nZVI and CMC-nZVI/BC used as remediation materials could obviously improve the remediation rate of Cr contaminated soil and when the ratio of CMC-nZVI to Fe0 was 2.5 g/Kg, the leachability of Cr(VI) and Crtotal can be reduced by 100% and 95.8% simultaneously. Moreover, sequential extraction procedure (SEP) showed that most exchangeable Cr converted to carbonate-bound and Fe-Mn oxides-bound, reducing the availability and leachability of Cr in the soil.
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Yu, Shu Zhen, Yue Cheng, Xiao Feng Fan, and Li Ping Xu. "Preparation of Coated CMC-nZVI Using Rheological Phase Reaction Method and Research on Degradation of Chloroform in Water." Materials Science Forum 847 (March 2016): 230–33. http://dx.doi.org/10.4028/www.scientific.net/msf.847.230.

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This study reported the synthesis of nanoscale zero-valent iron (nZVI) by rheological phase reaction method in the presence of sodium (CMC). The synthesized CMC coated nZVI (CMC-nZVI) was then characterized with x-ray diffraction (XRD) and transmission electron microscope (TEM) and was tested for the removal of chloroform from simulated groundwater. The investigated parameters in the uptake experiments included different adsorbents, initial concentrations of chloroform and different water flow. The results show that:(1) the prepared CMC-nZVI has good stability and dispersibility; (2) when the concentration of chloroform is 0.1 mg/L, the dosage of CMC-Fe0 is 0.01 g, the removal rate of chloroform is 91.2%;(3)The reaction follows the first-order kinetic reaction equation, and the apparent reaction rate constant increases with decreasing the concentration of chloroform.
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5

Ibrahim, Awad, Al-Farraj, and Al-Turki. "Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil." Sustainability 11, no. 23 (November 22, 2019): 6608. http://dx.doi.org/10.3390/su11236608.

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Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min-1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min-1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency.
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L. S. Silva, Larissa, Júlio A. Caldara, Ana Maria Rocco, Cristiano P. Borges, and Fabiana V. Fonseca. "Evaluation of Nano Zero-Valent Iron (nZVI) Activity in Solution and Immobilized in Hydrophilic PVDF Membrane for Drimaren Red X-6BN and Bisphenol-a Removal in Water." Processes 7, no. 12 (December 2, 2019): 904. http://dx.doi.org/10.3390/pr7120904.

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Fenton reactions that involve nano zero-valent iron (nZVI) have shown high promise in the removal of organic pollutants. In this work, nZVI stabilized with carboxymethyl cellulose (CMC) was evaluated for drimaren red X-6BN (DRX-6BN, 10 mg/L) and bisphenol-a (BPA, 800 mg/L) removal. Oxidation reactions were conducted for removal of both compounds by varying nZVI/CMC concentration (0.01–5 g/L), hydrogen peroxide (H2O2, 0.01–0.1 g/L), and pH (3–9). DRX-6BN degradation rate was the highest (kinetic constant (kobs) = 4.622 h−1) when working at pH 3 and 3 g/L of nZVI/CMC. Increasing H2O2 concentration could not improve the reaction. For BPA, all the conditions tested showed removals of more than 96% with 0.02 g/L of H2O2. This result was compared with the activity of nZVI loaded in hydrophilic PVDF (Polyvinylidene fluoride) membranes by polyacrylic acid (PAA) to entrap nanoparticles to the membrane surface. As expected, the attachment of nZVI onto the membranes diminished nanoparticles’ activity; however, it is important to highlight the need for preparing a stable catalytic membrane, which could enhance pollutant removal of microfiltration membranes’ systems. This was confirmed by the percentage of iron leaching from functionalized membranes, where a higher concentration of iron in the bulk solution leads to enhancement on BPA removal. Issues with BPA diffusion resistance inside the pores were overcome by conducting the nZVI/PAA/PVDF membranes in the cross-flow system, reaching 40% of BPA removal after 3 h of permeation.
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7

Fan, Tian En, Zhen Miao Shen, Meng Yao Jin, Jian Zhu, Ning Wang, and Zhen Zhang. "The Removal of Chromium(VI) by Synthesized CMC Stabilized Zero-Valent Iron Materials." Advanced Materials Research 534 (June 2012): 188–91. http://dx.doi.org/10.4028/www.scientific.net/amr.534.188.

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The removal of chromium(VI) by CMC stabilized nanoscale zero-valent iron (nZVI) and the effects of reaction temperature and CMC dosage on the removal efficiency of Cr(VI) were investigated through multi-group experiments on this paper. The experiental results revealed: (1) different dosages of CMC vary the degree of impact of the removal of Cr(VI), at the concentration of 0.5 g L-1, it has the highest removal efficiency. (2)The effect of temperature on the removal efficiency is negative. The higher the temperature is, the lower will be the removal efficiency. After 120 min of treatment, the removal efficiencies of Cr(VI) at various reaction temperatures from 0, 20, 30 to 40°C were recorded as 100%, 99.75%, 97.6%, 95.75%.
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8

Huang, Danlian, Yunhe Yang, Rui Deng, Xiaomin Gong, Wei Zhou, Sha Chen, Bo Li, and Guangfu Wang. "Remediation of Cd-Contaminated Soil by Modified Nanoscale Zero-Valent Iron: Role of Plant Root Exudates and Inner Mechanisms." International Journal of Environmental Research and Public Health 18, no. 11 (May 30, 2021): 5887. http://dx.doi.org/10.3390/ijerph18115887.

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In this study, the role of exogenous root exudates and microorganisms was investigated in the application of modified nanoscale zero-valent iron (nZVI) for the remediation of cadmium (Cd)-contaminated soil. In this experiment, citric acid (CA) was used to simulate root exudates, which were then added to water and soil to simulate the pore water and rhizosphere environment. In detail, the experiment in water demonstrated that low concentration of CA facilitated Cd removal by nZVI, while the high concentration achieved the opposite. Among them, CA can promote the adsorption of Cd not only by direct complexation with heavy metal ions, but also by indirect effect to promote the production of iron hydroxyl oxides which has excellent heavy metal adsorption properties. Additionally, the H+ dissociated from CA posed a great influence on Cd removal. The situation in soil was similar to that in water, where low concentrations of CA contributed to the immobilization of Cd by nZVI, while high concentrations promoted the desorption of Cd and the generation of CA–Cd complexes which facilitated the uptake of Cd by plants. As the reaction progressed, the soil pH and cation exchange capacity (CEC) increased, while organic matter (OM) decreased. Meanwhile, the soil microbial community structure and diversity were investigated by high-throughput sequencing after incubation with CA and nZVI. It was found that a high concentration of CA was not conducive to the growth of microorganisms, while CMC had the effect of alleviating the biological toxicity of nZVI.
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9

Wang, Yu, Zhanqiang Fang, Yuan Kang, and Eric Pokeung Tsang. "Immobilization and phytotoxicity of chromium in contaminated soil remediated by CMC-stabilized nZVI." Journal of Hazardous Materials 275 (June 2014): 230–37. http://dx.doi.org/10.1016/j.jhazmat.2014.04.056.

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10

Wu, Wenpei, Lu Han, Xiang Nie, Mingyue Gu, Jing Li, and Mengfang Chen. "Effects of multiple injections on the transport of CMC-nZVI in saturated sand columns." Science of The Total Environment 784 (August 2021): 147160. http://dx.doi.org/10.1016/j.scitotenv.2021.147160.

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Dissertations / Theses on the topic "CMC-nZVI"

1

Williams, Leslie Lavinia. "POST-EMPLACEMENT LEACHING BEHAVIORS OF NANO ZERO VALENT IRON MODIFIED WITH CARBOXYMETHYLCELLULOSE UNDER SIMULATED AQUIFER CONDITIONS." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1389376802.

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