A method for production of pure silica as fertilizer from industrial waste material

Globally, industrial waste such as fly ash, bottom ash, and slag in the thermal power energy, steel, and coal industry has been known as potential soil ameliorant and silica fertilizer. However, the use of those materials as ameliorant or Si fertilizer should consider negative environmental impact. Therefore, to use that material in Indonesia need to deal with the regulation and to prove its positive effect on the soil and plant. One innovative idea for recycling industrial waste is to use those raw materials to produce high purity Si as fertilizer. The objective of this research was to improve the solubility of Si from industrial waste material using a sol-gel technique. High purity of Si from materials was prepared using an acid and base solution. Two kinds of materials were selected to produce high purity Si, namely: bottom ash and fly ash. Silicon concentration of material before and after treatments were extracted by using two extraction method, namely: Na₂CO₃/NH₄NO₃ and 0.5 M HCl. The results show that the Si concentration of materials was higher with the sol-gel technique compared to Si concentration before treatment. In summary, this study provides an effective method to produce available Si from waste material.