BS12-assisted flotation for the intensification of SNPs separation from CMP wastewater using a novel flotation column

In view of the extremely small size, high stable dispersion and intricate colloidal nature of silica nanoparticles (SNPs) in chemical mechanical polishing (CMP) wastewater, they might not only have hazards for environment and human health, but also cause low separation efficiency by classical water-treatment processes. Thus, it would be an important challenge to develop an efficient flotation technology for the separation SNPs. For this propose, this paper firstly presented the interaction between SNPs and dodecyl dimethyl betaine (ambient-friendly surfactant). Secondly, a novel flotation column was developed for strengthening interfacial adsorption by micro-bubbles and enhancing foam drainage by internal of regular-decagonal hollow frustum (RHF). One vital finding was that the mixture of micro-bubbles and macro-bubbles was conducive to improving the flotation performance. Under the suitable operating conditions, the enrichment ratio (E) and recovery percentage (R) of SNPs could reach 30.4±1.5 and 90.8±4.5%, respectively. The great E and R were obtained simultaneously, revealing a good participation of RHF in the flotation. Without a doubt, owing to the low chemical reagent addition and the high flotation performance, it was clear that our flotation has huge implications for the separation of nanoparticles from their wastewaters.