Synthesis and Characterization of Nanoporous Silica and Silica Composites from Industrial Waste Materials

Abstract

In recent years, the reinforcing fillers have been an interesting subject of intensive research. In efforts of searching for the best reinforcing materials, the introduction and usage of improved grades of silica, development of dual fillers, introduction of biofillers such as corn starch fillers, introduction of polymeric fillers, and ground rubber as a recycling material and eco friendly filler has been taking place. At the same time, the development of low cost materials using industrial byproducts and wastes materials from local resources is of great interest to researchers.

In this thesis, chapter one reports on the quantitative synthesis of high purity nanoporous silica from wastes material (H2SiF6) of the phosphate fertilizer industry and Na2O.SiO2. The contamination of silica recovered from the wastes was compared with results obtained from the reaction of H2SO4 and Na2O.SiO2.The product obtained from the wastes material was 99.3% pure and that from H2SO4 was 99.1% pure. The quantity recovered were 22.30 g and 20.11 g, respectively. The product had superior properties suitable for various innovative applications and the process may significantly reduce the release of hazardous materials into the environment and confer economic benefits to the responsible industries. Chapter two describes on the use of waste tires as a source of carbon black for the synthesis of the carbon black silica composites. Tires do not decompose easily in the nature and may cause many environmental problems. The synthesis of novel low cost carbon black silica composite, using solids derived from waste tires and sodium silicate by precipitation method has been proposed. For this aim, waste tire (SBR_Styrene butadiene Rubber) was pyrolysed by using fixed bed reactor in deriving the sample which was further treated with concentrated HNO3 for sulphur and ash contents removing. The carbon black- silica composite was successfully prepared via precipitation using poly (vinyl pyrrolidone) (PVP) as a coupling agent. The product obtained via the proposed precipitation method had unique combination of properties suitable for various applications.