A novel Fe-loaded porous hydrothermal biochar for removing tetracycline from wastewater: Performance, mechanism, and fixed-bed column

The novel Fe-loaded porous hydrothermal biochars (FeKHCs) were successfully prepared by two-step synthesis of hydrothermal pretreatment and pyrolysis at different temperatures and used to remove tetracycline (TC) from wastewater. The biochar synthesized at 900 °C (FeKHC900) showed the highest specific surface area (SSA) (1487.55 m 2 /g) and porosity volume (V total ) (0.9951 cm 3 /g), which was significantly affected by hydrothermal pretreatment and K 2 C 2 O 4 activation. K 2 C 2 O 4 favored the micropores formation, which was beneficial to TC adsorption. Thus, FeKHC900 had the largest sorption amount of 606.52 mg/g for TC and outstanding performance for the other three antibiotics. Moreover, Fixed-bed column adsorption experiments proved that FeKHC900 has good dynamic adsorption performance (425.93 mg/g). The slightly reduced sorption amounts in different initial pH, coexisting ions, and humic acid (HA) indicated that FeKHC900 has a high resistance to interference and selective adsorption ability. Batch experiments revealed that TC adsorption was dominated by chemisorption, and the main mechanism referred to π-π interactions, pore-filling, H-bonding, and complexation. This work shares a simple and effective strategy for fabricating magnetic porous hydrothermal biochar as an efficient adsorbent to treat antibiotics.