Recycling of the Diamond-Wire Saw Powder Waste to Prepare Silica Nanoparticles

Abstract

Large amounts of hazardous diamond-wire saw powder (DWSP) waste were generated in the photovoltaic (PV) industry, which not only wasted the valuable resources but also polluted the environment and harmed the human health. In this study, a low-energy and simplified recycling method of the DWSP to prepare the silica nanoparticles (Si NPs) was proposed. The effect of sodium hydroxide concentration, temperature and dwell time on the leaching efficiency was investigated and optimized by the response surface methodology based on the Box-Behnken design (BBD) experiment. The optimal conditions were that the sodium hydroxide concentration of 1.41 mol/L, temperature of 87.16 °C and dwell time of 1.77 h. Under the optimized conditions, the leaching efficiency reached 99.80%, which was almost equal to the theory value predicted by the BBD model (99.68%). Kinetic analysis indicated that the dissolving process of the DWSP was consistent with the second-order homogeneous reaction model, and the apparent activation energy was 69.54 kJ/mol. Moreover, the final product was quite pure amorphous Si NPs with trace amount of absorbed water and sodium chloride impurity. This method is a feasible way to commercially recycle the DWSP in a low-energy and eco-friendly manner.