Sustainable production of pure silica from rice husk waste in Kazakhstan

This study aimed at developing a new synthesis method for the production of high purity silica from rice husks originated from different regions of Kazakhstan. The proposed eco-friendly method is compared with the conventional one reported in the literature which is accompanied by the use of significant amount of inorganic alkali and acids and direct combustion. In order to reduce the environmental impact, the mineral acid pre-treatment stage was either removed or replaced with organic acid pre-treatment, which reduced the amount of chemicals used during the synthesis and treatment process. The calcination temperature of 600 °C was selected based on thermogravimetric analysis. The average purity of silica samples obtained via different methods ranged from 84.81 to 99.66 wt%. The purity of the produced silica by use of the greener method was high reaching 98.67% with surface area up to 625 m ² /g.