Batch and continuous fixed-bed column adsorption of tetracycline by biochar/MOFs derivative covered with κ-carrageenan/calcium alginate hydrogels

Abstract

Due to the high dependence on tetracycline in the daily production and life of human beings, its abuse problem is serious, which affects the safety of the ecological environment. How to effectively remove residual tetracycline in the environment is an urgent problem to be solved. In this study, HKUST-1 was successfully composited with rice husk and wheat straw biochar by hydrothermal method, and then combined with κ-carrageenan and calcium alginate by cross-linking replacement method to prepare a novel modified biochar composite gel. Through a series of static adsorption experiments, the adsorption of TC on the two modified biochar composite gels reached equilibrium within 24 h and was dominated by chemical adsorption, and the maximum adsorption capacities for TC could reach 313.00 and 396.09 mg·g−1, respectively. The adsorption mechanism of TC on the modified biochar composite gels is mainly hydrogen bonding, electrostatic attraction, metal-organic complexation and π-π interaction. At the same time, the dynamic adsorption process was simulated through a fixed-bed column experiment, and the results showed that the modified biochar composite gels as a new type of adsorption material can be effectively applied to the removal of organic pollutants in actual sewage, providing basic support for future practical application research.