EICP改性稻壳生物炭吸附四环素的性能研究OA

Rice husk biochar was used as the raw material to fabricate an adsorbent via modification with enzyme-induced calcium carbonate precipitation(EICP),and enzyme-free and inactivated enzyme groups were established as controls.The microstructure and pore structure of the materials were characterized by SEM,FTIR and BET.The adsorption performance and mechanism of the modified biochar for tetracycline were investigated through adsorption kinetics,isotherm,pH effect experiments and five adsorption-desorption cycles.The results showed that EICP modification rendered the biochar surface rough and porous,with its specific surface area increased by 42.3%to 183.0 m2/g com-pared with the original biochar,the oxygen-containing functional groups increased signifi-cantly,and calcium carbonate was successfully loaded and firmly bonded to the biochar.The adsorption kinetics fitted well with the pseudo-second-order model(R2=0.9949),and the adsorption isotherm conformed to the Langmuir model(R2=0.997 1),indicating a monolayer chemical adsorption process,with the fitted maximum adsorption capacity reac-hing 49.55 mg/g.The optimal adsorption effect was achieved at pH=6.0(43.50 mg/g),and no obvious dissolution of calcium carbonate was observed in the pH range of 6.0-8.0.The ad-sorption performance of EICP-modified biochar was significantly better than that of unmodified biochar and the control samples.After five adsorption-desorption cycles,the adsorption capacity remained 78.6%of the initial value,showing good cyclic stability.