Sustainable removal of arsenic from waters by adsorption on blue crab, Portunus segnis (Forskål, 1775) chitosan-based adsorbents

Chitosan is the common name of a linear, copolymer of beta-(1- 4)-linked D-glucosamine and Nacetyl-D-glucosamine whose molecular structure comprises a backbone linked through glycosidic bonds. This polysaccharide has received a lot of attention due to its potential to remove heavy metals. In this context, this work was carried out with the aim of studying the efficacy of blue crab, Portunus segnis (Forskal, 1775) chitosan produced previously by the authors via a studied biological process to remove arsenic from aqueous solutions and therefore to be promoted in the environmental sector as effective ingredients for water decontamination. Batch experiments were performed to examine the effects of multiple parameters. Equilibrium isotherms were fitted using the Langmuir and Freundlich equation and finally, column experiments based on adsorption capacity were applied to better describe the adsorption process. The adsorption efficiency of powder from blue crab by-products, biological chitosan (BC) and commercially available chitosan (CC) was compared with that of magnetic chitosan (BMC) which was also prepared by a cross linking reaction using glutaraldehyde (GTA) in the presence of magnetite. Features of each chitosan forms were analyzed by a field emission-scanning electron microscopy (FE-SEM). The BMC has been found to be effective in removing arsenic. Indeed, both BMC and CC showed improved adsorption behavior of arsenic after the addition of magnetic nanoparticles. The arsenic removal behavior of most materials can be explained by a pseudo-second-order kinetic model mechanism. The pH of the arsenic solution depends on the acid-base state of the adsorbent, which further influences the adsorption performance.