Photocatalytic degradation of reactive black 5 azo dye by zinc sulfide quantum dots prepared by a sonochemical method

• Published in: Materials science in semiconductor processing 2013-08, Vol.16 (4), p.1109-1116
• Main Authors: Goharshadi, Elaheh K., Hadadian, Mahboobeh, Karimi, Mahdi, Azizi-Toupkanloo, Hossein
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Applied sciences; Azo; Chemistry; Cross-disciplinary physics: materials science; rheology; Degradation; Dyes; Exact sciences and technology; Fractures; General and physical chemistry; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Photocatalysis; Photocatalytic degradation; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Physics; Quantum dots; Qunatum dots; Reactive black 5; Semiconductor; Semiconductors; Ultrasonic irradiation; Zinc sulfide; Zinc sulfides
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2013.03.005

Zinc sulfide (ZnS) nanoparticles (NPs) with an average particle size of 2nm were successfully synthesized under ultrasonic irradiation without any surfactant and high temperature treatment. Prepared NPs were characterized by powder X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering analysis, and UV–vis absorption spectroscopy. The energy band gap of ZnS NPs was measured by UV–vis absorption spectroscopy. The photocatalytic activity of semiconducting sulfide quantum dots for degradation of an azo dye called reactive black 5 (RB5) was investigated. Results showed that the dye can be photocatalytically degraded with high rate by ZnS NPs under UV light irradiation. The kinetics of removal of RB5 in aqueous solutions was studied in a series of experiments which were varied in the amount of ZnS NPs, contact time, pH, dye concentration, and temperature. The experimental data were fitted very well in the pseudo-second order kinetic model. 95% of dye was successfully removed in 10min using 0.2g ZnS NPs in a neutral pH. A possible molecular mechanism for photocatalytic degradation of dye by ZnS NPs was also given.