Remediation and resource utilization of Cr(Ⅲ), Al(Ⅲ) and Zr(Ⅳ)-containing tannery effluent based on chitosan-carboxymethyl cellulose aerogel

Composite aerogel based on sodium carboxymethyl cellulose (CMC Na) and chitosan (CS), i.e., CS/CMC Na, was prepared through a sol-gel method. Then, CS/CMC Na was used for simulating the adsorption of metal ions (Cr 3+ , Al 3+ and Zr 4+ ) produced by the tanning industry. The adsorption process is consistent with the Langmuir isotherm adsorption model and pseudo-second order kinetics. The maximum fitted adsorption capacities of Cr 3+ , Al 3+ , and Zr 4+ could reach 250.0, 111.1, and 100.0 mg/g, respectively. After metal ion adsorption, the obtained composite materials (CS/CMC Na-Cr 3+ , CS/CMC Na-Al 3+ , and CS/CMC Na-Zr 4+ ) were used as re-tanning agents in the re-tanning process to leather. The re-tanning agent could increase the shrinkage temperature of leather by up to 5 °C. Compared with the traditional method, the method utilized in this study achieved the integration of mental ions-containing wastewater treatment and waste adsorbent/adsorbates recycling.