Efficient removal of tetracycline from water by tannic acid-modified rice straw-derived biochar:Kinetics and mechanisms

Rice straw-derived biochar (BC) has the advantage of low cost to remove tetracycline (TC) as a potential adsorbent, but it is limited by its poor adsorption capacity. On this basis, it was modified with tannic acid (TA) by precovering to increase the number of oxygen-containing functional groups. The structure and chemical properties of the modified BC were characterized and the adsorption behavior of TC on the modified BC was tested. The adsorption kinetics and isothermal data indicated that the adsorption performance of TC was improved after modification, and the adsorption capacity reached 308 mg/g, which was better than other congeneric adsorbents. The adsorption mechanism mainly included physical adsorption, electrostatic interaction, hydrogen bonding, and π–π interaction. The results of this study revealed that TA promoted the removal of TC from BC, and it was also beneficial to the rice straw-derived BC as an engineering adsorbent for the removal of TC from water.