Preparation of silver-nanoparticle-loaded magnetic biochar/poly(dopamine) composite as catalyst for reduction of organic dyes

In the present study, Ag nanoparticles loaded on polydopamine coated magnetic biochar (MC-PDA-Ag) catalyst was prepared by in-situ reduction approach. The morphology, composition, and structure of MC-PDA-Ag were characterized by the transmission electron microscopy (TEM), the scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). Catalytic reduction tests confirmed that MC-PDA-Ag catalyst showed excellent catalytic performance on the model dyes (MB, RhB, and MO) in the presence of NaBH4. The reduction efficiency of MB exceeded 90% by MC-PDA-Ag even under different initial pH (3–11) and different NaNO3 concentrations (0–0.5 M) within 5 min, indicating that the MC-PDA-Ag catalyst has potential strong universal adaptability in dye wastewater treatment. Furthermore, no significant decrease in catalytic ability was observed after 5 recycles, and the catalyst could be separated by an external magnet, indicating that this as-prepared catalyst exhibited high reusability and easy separability. These results suggest that MC-PDA-Ag composite catalyst can be used as an efficient catalyst for the reduction of organic dyes, and shows great potential application in wastewater treatment.