Study of the kinetics of thermal decomposition of the rice husks purified from cellulose

Abstract

A relevant task of today’s materials science is enhancing the characteristics of the materials combined with reducing energy consumption and environmental impact during their synthesis. Silicon dioxide is one of the materials for an extremely wide range of application. Currently, the requirements for the operational characteristics of silicon dioxide concern the production of nanosized amorphous silicon dioxide of high purity. The production of silicon dioxide can be made environmentally friendly by using the rice husks as a renewable and cheap raw material. The technology for production of silicon dioxide from the rice husks is less energy-consuming in comparison with traditional processing of quartz and this technology produces a significantly lower pollution impact on the environment. To obtain high purity silicon dioxide from the rice husks, the authors have proposed to extract the amorphous component of cellulose prior to the heat treatment of plant raw materials. This operation was carried out during 6 hours at a temperature of 100 °C with stirring the pulp in a 15 % sulfuric acid solution. Analysis of the phase composition of silicon dioxide obtained from the rice husks after the acid treatment showed that the amorphous phase of silicon dioxide is obtained in the temperature range of 600–650 °C. Based on the results of studying the kinetics of thermal destruction of rice husks under the non-isothermal conditions, a mathematical model of the process has been proposed, which makes it possible to determine the degree of decomposition of the rice husks, depending on the temperature of their heat treatment. This is necessary in the design of equipment for processing the rice husks in the production of high purity silicon dioxide.