Efficient removal of chlortetracycline hydrochloride by MOF-5-derived metal-free carbon materials with ultra-high specific surface area

Metal-organic frameworks (MOFs) have drawn great interest in pollutant adsorption due to their large specific surface area, abundant active sites, and regular pore structure, while they suffer from serious secondary pollution by inevitable metal spillage during pollutant treatment. Herein, we reported a series of MOF-derived metal-free carbon materials (MC-X-Y) for chlortetracycline hydrochloride (CTC) adsorption. The outcome pointed out that the MC-1000–60 prepared under 1000 °C for 60 min exhibited highest specific surface area (2299 m2·g−1) and maximum adsorption capacity for CTC (1588 mg·g−1 within 90 min), which was sixfold higher than that of commercial activated carbon and original MOF-5. The adsorption kinetics and isotherms of MC-1000–60 on CTC conformed to pseudo-second-order kinetic model and Langmuir model, respectively, indicating that the CTC adsorption was inclined to monolayer adsorption and dominated by chemisorption. Impressively, the CTC adsorption capacity for MC-1000–60 after used for 4 adsorption cycles could still reach up to 1199 mg·g−1. The co-existing ion and humid acid exerted insignificant interfering effect on CTC adsorption. The ultra-high adsorption capacity, fast adsorption rate, excellent recyclability and metal-free nature highlighted its light application prospect in solving the CTC-related pollution issues, being expected to be next generation of advanced adsorbents for removing emerging pollutants.