Silicon/Silica Colloidal Waste in the Semiconductor Industry: Challenges in Recovery and Potential Use

The backgrinding of silicon (Si) wafers has resulted in a loss of ∼70% of valuable Si materials. Consequently, an effluent known as diluted backgrinding wastewater (DBGW) is generated, containing nanosized silicon/silica colloids. Here, we discussed the challenges associated with the effective separation of Si-based waste from the DBGW based upon two perspectives, namely, a nanosized effect and a colloidal stability effect. Then, we revealed the limitation with the currently used coagulation-flocculation approach, which introduces impurities into the highly pure Si. Membrane-based filtration techniques have been adopted, but the serious fouling problem associated with colloidal Si/SiO₂ renders them almost impractical. Apart from that, the potential use of highly pure Si waste generated in the semiconductor industry in lithium ion batteries (LIBs) has been discussed. This Perspective aims to provide insights into the challenges associated with the Si recovery from DBGW and suggests its potential use in LIBs.