Fabrication of ZnO decorated porous chitosan beads for the sustainable bioremediation of Cr(VI) contaminated water

We report the preparation of both control chitosan and magnetic chitosan beads as biosorbents using chitosan as matrix and magnetite (Fe3O4) nanoparticles as reinforcement followed by detailed advanced characterization. The batch trials were performed to study the adsorption kinetics of biosorbents by removing As(III) and As(V) species from water systems. The experimental data was inserted into Langmuir and Freundlich's isotherms to undertake the mechanism and adsorption capacity of the test biosorbents. Under Langmuir's isotherm, maximum monolayer adsorption capacity (qmax) of the biosorbent was observed to be 73.69 and 79.49 mg/g for As(III) and As(V) species, respectively, under specified conditions. The optimum doses of 1.5 and 2 g/L of MCBB at pH 6.7 showed 99.5 and 99% removal of As(V) and As(III), respectively. The analysis demonstrated that the biosorption process obeyed pseudo 2nd order kinetics with linear regression coefficient (R2) of >0.999. The regeneration and reusability of biosorbents were also assessed.

Microencapsulation being an emerging technique has provided effective solution to the challenges faced by pharmaceutical, cosmetic, food agriculture and textile industries to deliver ingredients in their active forms to the target sites. Chitosan is a non-toxic, biodegradable and biocompatible amino polysaccharide which makes it useful for the encapsulation of various active ingredients with potential applications. Chitosan coating on food products, for example, gives them protection from possible antimicrobial attacks, antioxidants and extended shelf life. Likewise, its coating on pharmaceutics has valuable applications in preserving drug and their targeted delivery. In this review, we discuss the formation of chitosan, its properties, microencapsulation process, micro-capsular morphologies, selection of core and shell materials in addition to the process of chitosan encapsulation of various active ingredients and their applications in various fields of science and technology.