An environmentally-friendly chitosan-lysozyme biocomposite for the effective removal of dyes and heavy metals from aqueous solutions

Developing efficient and cost-effective adsorbents for removing heavy metals and dyes from water streams is of utmost importance as prolonged human and animals consumption might lead to adverse health effects. In the present study, an environmentally-friendly bio-composite of a polysaccharide with a protein was prepared, by conjugating chitosan to lysozyme using glutaraldehyde as a crosslinker. We investigated the utility of this chitosan-lysozyme biocomposite (CLC) as an adsorbent for the removal of methyl orange (MO) dye and hexavalent chromium (Cr(VI)) ions from aqueous solutions. CLC showed excellent removal of MO and Cr(VI) along with concurrent removal of other heavy metals such as Cd(II) and Ni(II) ions from aqueous mixtures. The maximum adsorption capacities of CLC for MO and Cr(VI) were as high as 435 and 216 mg g⁻¹, respectively. This study demonstrates the potential use of conjugated biopolymers such as chitosan and lysozyme for water treatment applications.