Silicon carbide in photocatalytic degradation of organic pollutants in wastewater of paper Industry

One of the major issues in water pollutions is the residual dyes and a wide variety of organic pollutants have been introduced into our natural water resources or wastewater treatment systems. There are different sources for these pollutants in water resources such as textile, paper and pulp, dye intermediates, pharmaceutical, and craft bleaching industries. These dyes are highly toxic and hazardous to the living organisms, so, the removal of these organic contaminants prior to discharge into the environment is essential. In recent years, semiconductor photocatalytic process has shown a great potential as a low-cost, environmental friendly and sustainable treatment technology to remove organic pollutants in the water/wastewater industries. The ability of this advanced oxidation technology has been widely demonstrated to remove persistent organic compounds and microorganisms in water. In this paper, we have selected silicon carbide as a good semiconductor with inherent characteristics such as high thermal conductivity, low thermal expansion coefficient, high hardness, superior corrosion resistance, good mechanical strength, high temperature capabilities, and wide ranging compatibility with nature. We have studied on the synthesis of porous doped silicon carbides at low temperature by using natural precursors. In this approach, nanoporous silicon carbides were synthesized by magnesiothermic method at 700°C. The physicochemical properties and the structure of obtained products were characterized by various techniques such as XRD, FT-IR, Raman, SEM, XPS, and BET. It was found that the structure of natural precursors can play an important role in determining the structure and properties of the final products. Doping can increase the surface area of obtained SiCs and reduced its band gap. These properties made SiC suitable as photocatalyst. Results show that doped-SiC can removed organic dye completely after 5 min. and also reduced COD of wastewater of paper industry significantly.