[Preparation of Adsorption Ceramsite Derived from Sludge Biochar].

Adsorption ceramsite (SKC) was prepared with biochar (BC) derived from municipal sludge and kaolin (KL) based on the optimized processing parameters to adsorb ciprofloxacin (CIP) in aqueous solutions. The CIP adsorption mechanism of SKC was investigated by adsorption kinetics and isotherm adsorption models, combined with the analysis of microstructure, pore structure, phase composition, and zeta potential. Furthermore, the heavy metal leaching toxicity was assessed using the toxicity characteristic leaching procedure (TCLP) method. The results showed that SKC, with 60% BC and 40% KL calcining at 1,050℃ for 5 min, showed an outstanding removal efficiency of CIP (65.34%). The pseudo-second-order equation agreed with the adsorption behavior and the Freundlich model described the adsorption process well. The adsorption process was a multilayer adsorption controlled by physical and chemical reactions. The leaching concentration of heavy metals, trapped by the mineral phases in SKC was much lower than that in BC, indicating low ecotoxicological risk. SKC possessed the ability to adsorb CIP with its developed porosity and characteristic mineralogical phases, including silicon aluminum oxide and iron oxide. This work provides a low-cost recyclable sorbing material to remove high concentration CIP from wastewater and offers a new idea for the large-scale safe use of BC.