Parameter study of ionized nanosilver recovery from wash water using emulsion liquid membrane process

Ionized nanosilver is a harmful and highly toxic owing to its association with other organic chemical especially with the aquatic organism cells. Therefore, it is crucial to treat the ionized nanosilver to preserve the environment. In this study, experiments were carried out using emulsion liquid membrane (ELM) process in order to investigate the performance of extraction and recovery of ionized nanosilver from wash water. This process involves three phase dispersion systems including external phase, membrane phase and internal phase. The ELM formulation consists of bis [2,4,4-trimethylpentyl] monothiophosphinic acid (Cyanex 302) as a carrier, Span 80 as a surfactant, kerosene as a diluent and thiourea in sulphuric acid (H₂SO₄) solution as stripping agent. This study has highlighted several effects of parameters including agitation speed, pH of external phase, and treat ratio. The concentration of the ionized nanosilver was measured using Atomic Absorption Spectrometry (AAS). The results have demonstrated that at optimum conditions, the percentages of extraction, stripping and recovery were 96, 84 and 80% respectively at 150 rpm of agitation speed, pH 2 and 0.33 of treat ratio.