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Sorption of Cr(VI) onto hdtma modified zeolitic tuffs

Sobolewska Paulina, Chojnacka Maria, Kramski Dawid, Warchoł Jolanta

Ecological Chemistry and Engineering. A

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2020

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Vol. 27, nr 1-2

1--9

EN

The removal of Cr(VI) from aqueous solutions was investigated using clinoptilolite and phillipsite-chabazite rich tuffs. These minerals were modified using hexadecyltrimethyl – ammonium bromide (HDTMA-Br) and used for Cr(VI) ions removal. The physicochemical characteristics of zeolitic minerals were revealed by XRD, XRF, BET and FT-IR techniques. The uptake capacities of modified zeolites were compared in batch sorption experiments. To predict the sorption isotherms and to determine the characteristic parameters for process design, three isotherm models the Freundlich, the Langmuir, and the Bilangmuir, were applied to experimental data. The data obtained reveal homogeneous Cr(VI) sorption on one kind of active sites on PC-HDTMA surface and heterogeneous sorption on two kinds of active sites on CL-HDTMA surface.

2

Szkodliwe substancje w materiałach włókienniczych - chrom sześciowartościowy

Chylewska K.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2016

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nr 11

39--40

EN

The article presents information on updating of the laboratory proper testing method used for determination of hexavalent chromium in textile materials. UV-VIS spectrofotometry was described for the determination of chromium (VI) in extraction solutions.

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Removal of hexavalent chromium from aqueous solution by adsorption on γ-alumina nanoparticles

Golestanifar H., Haibati B., Amini H., Dehghani M. H., Asadi A.

Environment Protection Engineering

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2015

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Vol. 41, nr 2

133--145

EN

The use of γ-alumina (γ-Al2O3) nanoparticles as adsorbent to remove Cr(VI) from aqueous solution was investigated using batch experiments. Adsorption experiments were carried out for various initial doses of Al2O3, initial concentrations of chromium(VI), contact times and pH. The structure and morphology of the sorbent was characterized by XRD, SEM, and TEM techniques. Results demonstrated that the removal efficiency of chromium(VI) was increased by increasing the contact time, initial concentration, and pH. The results of the study showed that adsorption of chromium by γ-alumina nanoparticles reached equilibrium after 60 min and after that a little change of chromium removal efficiency was observed. Furthermore, kinetics of chromium sorption was well fitted by pseudo-second order kinetic model, and well explained by the Freundlich isotherm (R2 > 0.992). Overall, alumina nanoparticles recognized as an effective sorbent to remove chromium(VI) from aqueous solutions.

4

Photocatalytic reduction of hexavalent chromium in aqueous solutions with zinc oxide nanoparticles and hydrogen peroxide

Assadi A., Dehghani M. H., Rastkari N., Nasseri S., Mahvi A. H.

Environment Protection Engineering

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2012

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Vol. 38, nr 4

5--16

EN

Photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solutions under UV irradiation and ZnO semiconductor catalyst was investigated using potassium dichromate as a model compound. The effects of pH, catalyst dose (0.05-0.15 g/dm3), Cr(VI) initial concentration (0.1-15 mg/dm3) and hydrogen peroxide concentration on photocatalytic reduction of Cr(VI) were investigated. The reduction rate of chromium was more favorable in acidic solution. Hydrogen peroxide was added as a reduction reagent for enhancement of the photoreduction. The process of photoreduction of Cr(VI) approximately followed first-order kinetics. Drinking water samples and wastewater were collected and photocatalytically treated for reduction of Cr(VI).