Glutaraldehyde base-cross-linked chitosan-silanol/Fe₃O₄ composite for removal of heavy metals and bacteria

We designed and synthesised a magnetic adsorbent (Fe₃O₄@Si-OH@CS-Glu) combining chitosan-silanol groups with glutaraldehyde as a cross-linking agent, which has improved physicochemical properties and can be used to remove multiple heavy metals and bacteria from polluted water. The adsorbent was characterised with SEM, XRD, FTIR, BET, VSM, and zeta potential. Under optimum conditions, the adsorption efficiencies of Fe₃O₄@Si-OH@CS-Glu for Cr⁶⁺, As⁵⁺, Hg²⁺, and Se⁶⁺ were as high as 90.5%, 73.5%, 91.6%, and 100% respectively. In addition, Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) can be removed after 2-4 adsorption cycles with 2.5 mg Fe₃O₄@Si-OH@CS-Glu. The main adsorption mechanism of the adsorbent for heavy metals and bacteria is electrostatic adsorption. Overall, the synthesised Fe₃O₄@Si-OH@CS-Glu adsorbent showed high removal efficiency and adsorption capacity with a stable structure and easy separation. It has promising applications for the removal of heavy metals and bacteria from water.