Reduction of organic dyes catalyzed by Ag Nanoparticles decorated on magnetic biochar

In the present work, silver nanoparticles were immobilized on the surface of magnetic biochar using nigella sativa aqueous extracton the surface of magnetic carbon quantum dots have been developed. The biochar samples were obtained by pyrolyzing under anN2 atmosphere with a flow rate of 100 mL/min at 450, 550 and 600 °C for 2 h and a heating rate of 10 °C/min. The biochar was leftto cool down to room temperature, and then it was stored in a sealed container before use. Biochar samples magnetized with Fe3O4magnetic nanoparticles. After that the surface of magnetic nanoparticles decorated with Ag by using Nigella sativa seed extract as acapping and reducing agent. the catalytic performance of Ag NPs/magnetic biochar was evaluated by the reduction of methylene blue(MB) and methyl orange (MO). the reduction of MO and MB was monitored spectrophotometrically at k max of 465 and 663 nm,respectively. The reduction of MO and MB using Ag NPs/magnetic biochar was completed within 8 and 1.5 min. using 5 mg of AgNPs/ magnetic biochar in the presence of 2 mL prepared aqueous solution NaBH4 (0.2 M) at room temperature. The recovering andreusability test of the Ag NPs//magnetic biochar was also investigated for the reduction of MO and MB. After the completion of thereaction (as monitored by UV–Vis spectroscopy), the catalyst was separated from the reaction mixture by external magnet and washedwith distilled water several times and then was dried and used for the next cycles. The reusability of the AgNPs/ magnetic biochar was studied for reduction of MO and MB under the present reaction conditions. The recycling results indicatedthat the catalyst was recycled for at least five times for 100% reduction of MO and MB.

Keywords:

Ag NPs/magnetic biochar , Reduction of organic dyes , Recyclability , Nigella sativa seed extract