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Preparation and Characterization of Chitosan Thin Films on Mixed-Matrix Membranes for Complete Removal of Chromium.

Nayak V, Jyothi MS, Balakrishna RG, Padaki M, Ismail AF - ChemistryOpen (2015)

Bottom Line: Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies.The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes.The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

View Article: PubMed Central - PubMed

Affiliation: Center for Nano and Material Sciences, Jain University Ramanagaram, Bangalore, 562112, India.

ABSTRACT
Herein we present a new approach for the complete removal of Cr(VI) species, through reduction of Cr(VI) to Cr(III), followed by adsorption of Cr(III). Reduction of chromium from water is an important challenge, as Cr(IV) is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

No MeSH data available.


Reduction of CrVI in the dark and sunlight using a) PSf/TiO2/CS and b) PSf/CS membranes; error bars represent the SD.
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fig11: Reduction of CrVI in the dark and sunlight using a) PSf/TiO2/CS and b) PSf/CS membranes; error bars represent the SD.

Mentions: The error graph in Figure 11 a represents the reduction of CrVI using PSf/TiO2/CS membrane, and it is observed that in the presence of sunlight the reduced chromium undergoes back reaction and is recovered. This is due to the presence of TiO2, which acts as a photocatalyst in the presence of sunlight. TiO2 produces an e−–h+ pair upon excitation of light at λ≥400 nm. These electron hole pairs under aqueous conditions and atmospheric oxygen gives rise to a number of free radicals as follows:345


Preparation and Characterization of Chitosan Thin Films on Mixed-Matrix Membranes for Complete Removal of Chromium.

Nayak V, Jyothi MS, Balakrishna RG, Padaki M, Ismail AF - ChemistryOpen (2015)

Reduction of CrVI in the dark and sunlight using a) PSf/TiO2/CS and b) PSf/CS membranes; error bars represent the SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4522177&req=5

fig11: Reduction of CrVI in the dark and sunlight using a) PSf/TiO2/CS and b) PSf/CS membranes; error bars represent the SD.
Mentions: The error graph in Figure 11 a represents the reduction of CrVI using PSf/TiO2/CS membrane, and it is observed that in the presence of sunlight the reduced chromium undergoes back reaction and is recovered. This is due to the presence of TiO2, which acts as a photocatalyst in the presence of sunlight. TiO2 produces an e−–h+ pair upon excitation of light at λ≥400 nm. These electron hole pairs under aqueous conditions and atmospheric oxygen gives rise to a number of free radicals as follows:345

Bottom Line: Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies.The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes.The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

View Article: PubMed Central - PubMed

Affiliation: Center for Nano and Material Sciences, Jain University Ramanagaram, Bangalore, 562112, India.

ABSTRACT
Herein we present a new approach for the complete removal of Cr(VI) species, through reduction of Cr(VI) to Cr(III), followed by adsorption of Cr(III). Reduction of chromium from water is an important challenge, as Cr(IV) is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

No MeSH data available.