The catalytic activity of the coupled CdS-AgBr nanoparticles: a brief study on characterization and its photo-decolorization activity towards methylene blue
Seyyedeh Atefeh Mirsalari, Alireza Nezamzadeh‐Ejhieh
Abstract
ABSTRACT As synthesized coupled CdS-AgBr nanoparticles (NPs) (CCAN) were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and ultraviolet-visible diffuse reflectance spectroscopy techniques. The surface charge of the individual CdS NPs, AgBr NPs and the resulted coupled CdS-AgBr system was estimated at 6.3, 4.6, and 5.6, respectively. Then, the pho- tocatalytic activity of the individual and the coupled systems was tested towards decolorization of methylene blue (MB) in aqueous solution and about 39%, 60%, and 80% of MB molecules were respectively decolorized by CdS NPs, AgBr NPs, and CdS-AgBr CCAN during 30 min photocatalytic decolorization experiments. Change in a mole ratio of the involved semiconductors of the coupled system changed the photo decolorization activity and the best response was obtained for the catalyst with a mole ratio of 1:4 CdS:AgBr. Kinetic of the process was followed and the results showed that the Langmuir-Hinshelwood model can model the process and a relatively fast reaction with a rate constant about 3.49 × 10 –2 min –1 was distinguished. Mineralization extent of MB aqueous solution during the decolorization experiments was followed by chemical oxygen demand (COD) technique and the results showed that the initial COD value of 1,280 mg O 2 L –1 was decreased to 640 and 480 mg O 2 L –1 after 30 and 60 min of decolorization of MB solution. The catalyst retained its initial activity during 4 successive reusing runs.