A low cost magnetic biochar manufactured solely from solid wastes by one-step pyrolysis for removal of tetracycline

Water remediation of toxic chemicals using effective absorbents has received considerable attention recently. In the present study, using peanut shell and red mud as raw materials, a low-cost magnetic biochar (MBC) was prepared via a one-step pyrolysis method, without any chemical input or wastewater discharge, for tetracycline (TC) removal from water. Material characterization and batch processing experiments were conducted to investigate the material properties and environmental factors affecting adsorption performance. The adsorption mechanism of MBC on TC was revealed through adsorption isotherms, adsorption kinetics and thermodynamics analyses. The results show that the MBC material with developed pore structure and rich functional groups is uniformly loaded with nano-Fe₃O₄ particles, and its maximum adsorption capacity of TC reaches 87.39 mg/g, and can be separated from water within 30 s. The simulated removal experiments of MBC demonstrate its promising applications for the removal of various pollutants, such as antibiotics, heavy metals and dyes in real water systems. A regeneration study revealed the high reusability (> 70%) and acceptable stability of MBC even after five cycles. Moreover, the one-step pyrolysis method exhibited good generality for manufacturing MBC from different biomass and significantly reduced cost.