Magnetic Schiff's base sorbent based on shrimp peels wastes for consummate sorption of chromate

Abstract

Magnetic Schiff's base chitosan composite has been prepared starting from shrimp peels as a raw material. Chitosan extraction involved three main stages as preconditioning, demineralization deproteinization and deacetylation. Chitosan modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The synthetic hybrid composite was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses and tested as sorbent for Cr(VI) recovery from aqueous solution. The performance of the sorbent was systematically evaluated by batch sorption experiments, followed by equilibrium and kinetic studies with different mathematical models. The isotherm study demonstrate that the sorbent achieved 99.1% (sorption capacity; 252.45 mg g^-1) removal efficiency in Cr(VI) solution with concentrations up to 400 mg/L. Experimental data gave better mathematical fitting towards pseudo-second-order kinetic model and Langmuir isotherm model. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous and contributes to increase the randomness of the system. The sorbent could be recycled for three cycles of sorption/desorption.