Removal of Chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron

Shi, Lina; Zhang, Xin; Chen, Zuliang

doi:10.1016/j.watres.2010.09.025

Cited by 656 publications

(252 citation statements)

References 18 publications

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“…These exchanged Fe 2+ ions were reduced to Fe 0 with NaBH 4 , which resulted in good dispersed nZVI on the zeolite surface. Similar results have been reported using bentonite and kaolinite supported iron nanoparticles (ÜzÜm et al 2009;Shi et al 2011). Measuring the diameters of 100 particles in different regions of a given image grid can be used to quantify the particle size .…”

Section: Methodssupporting

confidence: 88%

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Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles

2014

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Sepehri S., Heidarpour M., Abedi-Koupai J. (2014): Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles. Soil & Water Res., 9: 224-232.A report on the synthesis and characterization of nanoscale zero-valent iron in the presence of natural zeolite as a stabilizer is presented. This novel adsorbent (Ze-nZVI) was synthesized by the sodium borohydride reduction method. The scanning electron microscopy (SEM) images revealed that the stabilized nZVI particles were uniformly dispersed across the zeolite surface without obvious aggregation. The synthesized Ze-nZVI material was then tested for the removal of nitrate from aqueous solution. The effect of various parameters on the removal process, such as initial concentration of nitrate, contact time, initial pH, and Ze-nZVI dosage, was studied. Batch experiments revealed that the supported nZVI materials generally have great flexibility and high activity for nitrate removal from aqueous solution. The nitrogen mass balance calculation showed that ammonium was the major product of nitrate reduction by Ze-nZVI (more than 84% of the nitrate reduced); subsequently the natural zeolite in Ze-nZVI removed it completely via adsorption. The kinetic experiments indicated that the removal of nitrate followed the pseudo-second-order kinetic model. The removal efficiency for nitrate decreased continuously with an increase in the initial solution pH value and Ze-nZVI dosage but increased with the increase in the initial concentration of nitrate. The overall results indicated the potential efficacy of Ze-nZVI for environmental remediation application.

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Section: Methodssupporting

confidence: 88%

“…The nitrate removal (%) is increased rapidly from 56.6 to 74.2% for Ze-nZVI. These phenomena can be attributed to the increase in the available active sites and larger surface area with the increase in the Ze-nZVI dosage (Huan et al 2006;Shi et al 2011).…”

Section: Methodsmentioning

confidence: 99%

Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles

2014

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“…Widely employed methods for Cr(VI) removal include chemical precipitation (primarily by reducing Cr(VI) to Cr(III)), ion exchange, electrodialysis, reverse osmosis, and adsorption (Rengaraj, Yeon, and Moon 2001;Gheju and Balcu 2011;Shi, Zhang, and Chen 2011;Yari et al 2013). Sludge production, cost unaffordability, and unpleasant tests are among the challenges encountered for most of the methods especially in developing countries.…”

Section: Introductionmentioning

confidence: 99%

Freeze Desalination as Point of Use Water Treatment Technology: A Case of Chromium (VI) Removal from Water

Melak

Ambelu

Laing

et al. 2017

The 2nd International Electronic Conference on Water Sciences

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Options to develop tanning industries could be hindered even in the presence of huge leather industry raw materials due to the requirements of high-tech contaminant removal technologies, especially in developing countries. This study was initiated to investigate the efficiency of freeze desalination for Cr(VI) removal using refrigerators to generate fresh water. Synthetic solutions that represent major ion compositions of drinking water as well as deionized water to which known concentrations of Cr(VI) spiked into it, were added and frozen in a closed freezer unit. The effects of different parameters such as initial concentration, freeze duration, ice nucleation, fraction of ice volume, and influence of co-occurring ions were evaluated in relation to the quality of produced ice. The physicochemical characteristics of the produced meltwater were also evaluated. A high total water recovery of up to 85% was achieved in the experimental evaluation. Cr(VI) removal efficiency of up to 80% from simulated tap and 93 to 97% for deionized water spiked with Cr(VI) were found in this batch partial freezing. Freeze desalination was found to be relatively viable desalination technology in terms of quality of water produced, options on the use of cost effective refrigerants and technologies which could have a pertinent importance to save energy consumption of freezers.

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“…However, it cannot successfully remediate highlime COPR because its mineralogical complexity prevents effective Cr(VI) availability for subsequent conventional chemical reduction [3,17]. In recent years nanoscale zero-valent iron (nZVI) has been developed and demonstrated to be an effective reductant for the immobilization of Cr(VI) in water and soils [18][19][20][21]. Nevertheless, limited research is conducted on the leachability and speciation of Cr in COPR in the presence of nZVI [22].…”

Section: Introductionmentioning

confidence: 99%

Reduction and immobilization of chromate in chromite ore processing residue with nanoscale zero-valent iron

et al. 2012

Journal of Hazardous Materials

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Keywords:Chromite ore processing residue (COPR) Nanoscale zero-valent iron (nZVI) X-ray absorption near edge structure (XANES) spectroscopy Chromate leachability Speciation a b s t r a c t Chromite ore processing residue (COPR) poses a great environmental and health risk with persistent Cr(VI) leaching. To reduce Cr(VI) and subsequently immobilize in the solid matrix, COPR was incubated with nanoscale zero-valent iron (nZVI) and the Cr(VI) speciation and leachability were studied. Multiple complementary analysis methods including leaching tests, X-ray powder diffraction, X-ray absorption near edge structure (XANES) spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to investigate the immobilization mechanism. Geochemical PHREEQC model calculation agreed well with our acid neutralizing capacity experimental results and confirmed that when pH was lowered from 11.7 to 7.0, leachate Cr(VI) concentrations were in the range 358-445 mg L −1 which contributed over 90% of dissolved Cr from COPR. Results of alkaline digestion, XANES, and XPS demonstrated that incubation COPR with nZVI under water content higher than 27% could result in a nearly complete Cr(VI) reduction in solids and less than 0.1 mg L −1 Cr(VI) in the TCLP leachate. The results indicated that remediation approaches using nZVI to reduce Cr(VI) in COPR should be successful with sufficient water content to facilitate electron transfer from nZVI to COPR.

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Removal of Chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron

Cited by 656 publications

References 18 publications

Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles

Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles

Freeze Desalination as Point of Use Water Treatment Technology: A Case of Chromium (VI) Removal from Water

Reduction and immobilization of chromate in chromite ore processing residue with nanoscale zero-valent iron

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