Biochar from de-oiled Chlorella vulgaris and its adsorption on antibiotics

Abstract

High-performance biochar was prepared using de-oiled Chlorella vulgaris biomass as the raw material and KOH as the modifying activator. The properties of the biochar as an adsorbent for the removal of tetracycline (TC) and enrofloxacin (ENR) were investigated under different conditions by varying the amount of the Chlorella vulgaris de-oiled biomass (DB) input. The surface structure and physicochemical properties of different Chlorella vulgaris biomass charcoal (CBC) samples were studied and compared, and the best adsorption performance of the biomass charcoal was obtained when DB = 7. Through orthogonal analysis, it was determined that the optimal adsorption condition of CBC 7 on TC was 0.004 g (pH 3), which resulted in a removal rate of 96.45% and a maximum adsorption capacity of 241.1363 mg g−1, and on ENR was 0.004 g (pH 7), which resulted in a removal rate of 100% and a maximum adsorption capacity of 256.3326 mg g−1. The results of the kinetic fitting show that the adsorption of TC and ENR by CBC 7 was consistent with the pseudo-secondary kinetic equation. The maximum adsorption capacities can reach 299.8974 and 352.6736 mg g−1. Langmuir and Freundlich adsorption isotherm models were used to describe the adsorption equilibrium of TC and ENR by CBC 7. The results show that the adsorption of TC and ENR are in accordance with the Langmuir isotherm.