Highly toxic Cr (VI) adsorption by (chitosan-g-PMMA)/silica bionanocomposite prepared via emulsifier-free emulsion polymerisation.

This work focuses on developing some composites of desirable properties mainly for heavy metal ion adsorption from the water bodies leading to water remediation. Adsorption of Cr(VI) by a novel biopolymer-based hybrid nanocomposite material has been synthesized via emulsifier-free emulsion polymerisation technique and investigated its assess as proposed use. Chitosan is a biocompatible, biodegradable and non-toxic material, hence this biopolymer has been selected in this research work. The chemical modification of the biopolymer chitosan has been achieved via grafting of poly(methyl methacrylate) (PMMA) and crosslinker silica gel was added in order to improve the mechanical strength of the nanocomposite in nitrogen atmosphere taking ammonium persulphate as initiator. The resulting composite samples were characterized by using XRD, FTIR, SEM and TEM. Further, the biodegradability of the samples was studied at different time intervals from 15days to 6months and the so produced nanocomposite exhibited good biodegradability. Adsorption of Chromium (Cr) was investigated by varying the contact time between the adsorbate (Cr), the nanocomposite, pH of the solution and the doses of the composite. The optimum result for chromium removal was found at pH-4 and this result showed its use efficiently for the treatment of wastewater containing Cr (VI).