Enhanced adsorption of tetracycline by the modified tea-based biochar with the developed mesoporous and surface alkalinity

A tea residue-based biochar, Fe-BCK0.5-VB6, was obtained by pyrolysis with KOH activation and alkalization with vitamin B6, to develop the mesopore structure and functionalized surface to improve the adsorption performance on tetracycline (TC). An increased specific surface area of 455 m2·g-1 and expanded mesopore volume of 0.138 cm3·g-1 for Fe-BCK0.5-VB6, were observed. The Avrami-fractional order kinetics and Langmuir isotherm models best fitted the experimental data, indicating the characteristics of multiple kinetic stages and monolayer of TC adsorption process. Several possible interactions, including acid-base reaction, pore filling, electrostatic interactions, π-π interactions, and hydrogen bonding forces, were participated in the attachment of TC. This novel mesoporous biochar with enhanced surface alkalinity is expected with a viable future role as an efficient adsorbent in the remedies of acidic antibiotics wastewater pollution.