Recovery of ionized nanosilver from wash water solution using emulsion liquid membrane process

The increasing numbers of product containing nanosilver have raised a great concern about their possible impact in the environment especially in the ionic form which leads to the toxicity problem when the association occurs with the organism cells. Therefore, the main focus of this study was to investigate several parameters influencing the recovery of ionized nanosilver from wash water using emulsion liquid membrane (ELM) process. This process involves three phases dispersion system including external, membrane and internal phase. The membrane phase was prepared by dissolving bis [2, 4, 4-trimethylpentyl] monothiophosphinic acid (Cyanex 302) as a carrier and Sorbitan Monooleate (Span 80) as a surfactant in kerosene as a diluent. Thiourea in Sulfuric acid (H₂SO₄) was used as a stripping agent in the internal phase. The important parameters such as extraction time, carrier and stripping agent concentrations were investigated. All experiments were conducted in batch system. The concentration of the ionized nanosilver was measured using Atomic Absorption Spectrometry (AAS). The result demonstrated that almost 100% of silver ion was extracted with 91% have been recovered within 5 minute of extraction time using 0.005 M Cyanex 302 and 1.0 M Thiourea in 1.5 M H₂SO₄. Hence, ELM was proven to be a very promising technique for the simultaneous extraction and recovery of ionized nanosilver from wash water.