A facile and universal method to purify silica from natural sand

The major constituents of sand are silica and silicates. The facile and low-cost purification technology of silica from natural sand is of magnificent importance to the industrial applications of silicon-based materials. Herein, we report a green, low-cost, and universal method to purify silica from natural sand. Sand from deserts, rivers, and seas is selected as the representative of natural sand. The initial purity of silica is 52.1 wt% for desert sand, 39.3 wt% for river sand, and 35.8 wt% for sea sand. High-purity silica has been successfully separated and purified from natural sand via ball milling, reacting with 30 bar CO2 and hydrochloric acid. The purity of silica derived from natural sand reaches >96 wt%. In this work, the mechanism for the purification of silica from natural sand is discussed. This study provides a new method to separate high-purity silica from natural sand without the generation of toxic and harmful substances.