Preparation and adsorption properties of magnetic chitosan/sludge biochar composites for removal of Cu2+ ions

Abstract The magnetic chitosan/sludge biochar composite adsorbent was prepared using chitosan, Fe 3 O 4 , and sludge biochar as raw materials. The composite adsorbent was able to achieve rapid solid–liquid separation under an applied magnetic field. The morphology and microstructure of the composite adsorbent were characterized by FTIR, XRD, SEM, VSM, and BET analysis. The adsorption performance of the composite adsorbent on Cu 2+ was investigated through static adsorption experiments, and the effects of adsorbent dosage, initial concentration of Cu 2+ , initial pH of the solution, and adsorption temperature on the adsorption efficiency of Cu 2+ were discussed. The results showed that chitosan and Fe 3 O 4 were successfully loaded on sludge biochar. When the initial concentration of Cu 2+ was 30 mg/L, the dosage of the magnetic chitosan/sludge biochar composite material was 0.05 g, the adsorption time was 180 min, pH was 5, and the temperature was room temperature, the maximum removal rate of Cu 2+ reached 99.77%, and the maximum adsorption capacity was 55.16 mg/g. The adsorption kinetics and adsorption isotherm data fitted well with the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, indicating that the adsorption process was chemisorption with monolayer coverage.