Recovery of nanoparticles from wastewater by foam fractionation: Regulating bubble size distribution for strengthening foam drainage

Abstract

Abstract The application of nanoparticles (NPs) in many fields generated large amounts of wastewater which would result in resource loss and environmental pollution. In this work, foam fractionation was used to recycle NPs from their aqueous suspensions and a novel method was developed to strengthen foam drainage through regulating bubble size distribution. The results showed that the adjacent bubbles with different size were easy to coalesce and then the bubble size and surface excess were enhanced simultaneously. Thereby strengthening foam drainage and foam stability simultaneously. The enrichment ratio of NPs increased approximately 45% with almost no loss of recovery percentage by using this method. The recycle efficiency of NPs was also affected by their structures and shapes that the recycle of tubular NPs was more efficient than globular NPs. Under the suitable conditions, the enrichment ratio and recovery percentage of silica nanoparticles (SNPs) and carbon nanotubes (CNTs) were 7.1, 90.1% and 9.9, 94.5%, respectively.