Functionalized construction of highly aromatic condensed graphitized biochar for tetracycline adsorption

Designing biochar for the efficient removal of specific pollutants remains a significant challenge. In this work, a graphitized biochar with large carbon clusters (HBC700) was synthesized specifically for the removal of tetracycline. HBC700 exhibited outstanding adsorption performance, with a maximum adsorption capacity of 257.04 mg·g⁻¹ , which is 4.72 times that of the pristine biochar. The superior performance is attributed to its low electrical resistance, which facilitates electron transfer at the interface, enabling rapid and efficient tetracycline removal. After tetracycline adsorption, the structure of HBC700 became more ordered, forming a stable honeycomb arrangement. HBC700 also demonstrated high regeneration stability, maintaining a 94.85 % removal rate after five cycles, and achieving 100 % removal after H₂O₂ purification. Furthermore, HBC700 achieved over 98 % tetracycline removal in both tap water and wastewater, highlighting its potential for real-world applications. • The graphitized structure enhanced tetracycline adsorption to 4.72 times that of the original biochar. • The low resistance of HBC700 facilitates electron transfer. • After TC adsorption, HBC700 becomes more tightly packed.