Controlled Synthesis of Bimetallic Co/Zn Zeolite Imidazolate Framework-Functionalized Pine Sawdust for Enhanced Tetracycline Elimination

The persistent residues and accumulation of tetracycline hydrochloride (TC) in aquatic environments will significantly threaten environmental safety and human health. Effectively achieving precise antibiotic removal from pollutant-laden aqueous environments has become a critical technological challenge that urgently needs resolution. In recent years, antibiotic adsorption technologies based on biomass materials have demonstrated considerable potential for immobilizing and removing aqueous pollutants, owing to their low costs and abundant porous structures. This study successfully developed a novel composite material, Co/Zn-ZIFs@pine sawdust, by immobilizing bimetallic ZIFs onto pine sawdust. This composite combines environmental friendliness with high adsorption efficiency and exhibits exceptional performance in removing TC contaminants from water. Comprehensive characterizations were conducted to determine the functional groups, elemental composition, morphology, thermal stability and adsorption mechanisms of Co/Zn-ZIFs@pine sawdust. The impact of diverse factors on TC adsorbing behavior was systematically investigated, including the Co/Zn ratio in ZIFs, initial TC concentration, adsorption time, temperature and aqueous pH. The adsorption well obeys a pseudo-2nd-order kinetic equation (R 2 = 0.999) and the Langmuir isotherm model. Under the optimal pH of 7.0, the Co/Zn-ZIFs@pine sawdust achieved a considerable maximum adsorption capacity of 719.0   mg·g -1 . Notably, the composite exhibited excellent reusability, retaining 64.2% of its initial adsorption capacity after five consecutive cycles. These results demonstrate that Co/Zn-ZIFs@pine sawdust is highly effective for removing TC from aqueous solutions. This research provides a novel approach for remediating antibiotic-contaminated water, and demonstrates significant potential for valorization of biomass wastes.