چكيده به لاتين
Abstract
Environmental pollution in global scale and the lack of clean energy sources have led scientists to focus on environmental issues, in particular clean chemical and physical materials and processes. One of the ways to inhibit environmental pollution is to decompose toxic and harmful molecules and convert them into non-toxic substances by photocatalytic processes. Nickel sulfide has attracted a lot of attentions as a photocatalytic material due to its small band gap (1.92-2.41 eV), abundance and cheapness. In this study, nanoparticles of nickel sulfide were synthesized by solution combustion synthesis method using fuels such as tiourea and thioacetamide as sources of sulfur and mixtures of these fuels with glycine, urea and citric acid. The fuel combination was used to change the combustion conditions, including temperature, amount and combustion gas composition. In this study, in the synthesis by tiourea-urea fuel composition, in addition to the conventional heat treatment, microwave was also used as a heat source to study the microstructural difference and the differences of their forming phases. The synthesized powder was investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), diffuse reflection spectroscopy (DRS) and ultraviolet-visible spectroscopy (UV-Visible) methods, and also a thermal analysis (TGA/DTA) was confirmed on the gel. The results obtained from the analysis of the powders showed the formation of various compounds such as NiS , NiS2 and composites such as NiS-NiS2 and NiS-Ni3S2, which were mainly pseudo spherical morphology. The investigation of photocatalytic activity of synthesized powders showed good results, so that nickel sulfide powder has the ability to absorb methylene blue up to 88.4% and degrade 74.3% under visible radiation exposure.
Key words: Nickel sulfide, Solvent combustion synthesis, Fuel type, Fuel composition, Photocatalyst, Microwave heating
