Ionic solid-impregnated sulphate-crosslinked chitosan for effective adsorption of hexavalent chromium from effluents

Abstract

Microwave-assisted tetrabutyl ammonium-impregnated sulphate-crosslinked chitosan was synthesized for enhanced adsorption of hexavalent chromium. The adsorbent obtained was extensively characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray studies.Various isotherm models such as Langmuir, Freundlich and Dubinin-Radushkevich were studied to comprehend the adsorption mechanism of hexavalent chromium by the adsorbent. Maximum adsorption capacity of 225.9 mg g -1 was observed at pH 3.0 in accordance with Langmuir isotherm model. The sorption kinetics and thermodynamic studies revealed that adsorption of hexavalent chromium followed pseudo-second-order kinetics with exothermic and spontaneous behaviour. A column packed with 1 g of adsorbent was found to give complete adsorption of Cr(VI) up to 900 mL of 200 mg L -1 solution which discerns the applicability of the adsorbent material for higher sample volumes in column studies. The effective adsorption results were obtained due to both ion exchange and ion pair interaction of adsorbent with hexavalent chromium. Greener aspect of overall adsorption was regeneration of the adsorbent which was carried out using sodium hydroxide solution. In the present study, the regenerated adsorbent was effectively reused up to ten adsorptiondesorption cycles with no loss in adsorption efficiency.

Chitosan entrapped microporous activated carbon composite as a supersorbent for remazol brilliant blue R

“…The pH PZC of Cs-C was determined by a previously reported method 32 in order to establish the surface charge on the adsorbent. For this, 50 mL 0.1 M NaCl solutions with varying initial pH from 2.0 to 9.0 were taken in a series of conical flasks.…”

Fe(III)–Chitosan Microbeads for Adsorptive Removal of Cr(VI) and Phosphate Ions

“…For the structural/functional modification of a chitosan matrix on free amine groups on deacetylated units or hydroxyl groups on carbon, C 3 and C 6 have been used [19]. Chemical modifications involve grafting, cross-linking, and impregnation with inorganic and organic moieties for Cr(VI) ion adsorption [20]. Meanwhile, physical modifications involve phase modifications of membranes, beads, hydrogels, nanofibers, and so on.…”