Effects of modification and magnetization of rice straw derived biochar on adsorption of tetracycline from water

[Display omitted] •Modified magnetic biochar showed enhanced TC adsorption capacity reaching to 98.33 mg/g.•Adsorption occurs mainly by hydrogen bonding and pore-filling effect.•A stable TC removal rate of 69% was maintained after five cycles.•Nitrate nitrogen and phosphorus removal reach to 75.23 mg/g and 83.33 mg/g, respectively. Rice straw derived biochar shows low-cost superiority as a potential adsorbent in tetracycline (TC) removal, but limited by its poor adsorption capacity and N, P leaking risk. Herein, an alkali-acid combined and magnetization method was proposed for its modification. The sorption kinetic and isotherm data showed modification enhanced the performance for tetracycline removal with adsorption capacity up to 98.33 mg·g−1. The strong adsorption mechanisms were dominated by hydrogen bonding and pore-filling effect due to the increase of specific surface area and pore volume. Furthermore, the effect of pH was insignificant over a pH range from 3 to 10. The strong competition between ionic and TC was identified, where Ca2+ and PO43− markedly inhibited the sorption. The enhanced TC adsorption, strong N and P removal, easy magnetic recovery, and good reusability in water samples entrusted it with good potential for wastewater treatment and rice straw resource disposal.