Recovery of ionized nanosilver by emulsion liquid membrane process and parameters optimization using response surface methodology

Abstract

A B S T R A C TThe discharge of silver ions from nanosilver-based product into the environment has raised the ecological and human health concern due to the toxicity of silver ion, particularly on the release behaviour of ionized nanosilver from the wastage. Therefore, recovery of ionized nanosilver is highly necessary. In this research, emulsion liquid membrane technique was employed for ionized nanosilver recovery from the domestic waste. The liquid membrane consists of kerosene, Span 80, Cyanex 302 and acidic thiourea as the diluent, surfactant, carrier and stripping agent, respectively. The emulsion stability was investigated at different surfactant concentrations, agitation and homogenizer speeds. Response surface methodology (RSM) was applied for the optimization of process variables including treat ratio, sulphuric acid (H 2 SO 4 ) and thiourea concentration in the recovery process. The results showed that the most stable emulsion was observed at 3% w/v of surfactant, 10,000 and 150 rpm of homogenizer and agitation speed, respectively. The optimum conditions obtained for the recovery process using RSM were: treat ratio (0.256), H 2 SO 4 concentration (0.75 M) and thiourea concentration (0.85 M). At the optimized condition, the maximum recovery of ionized nanosilver was 84.74%.

Emulsion Liquid Membrane for Pesticides Removal from Aqueous Solution: Emulsion Stability, Extraction Efficiency and Mass Transfer Studies

“…Further increase in the homogenizer speed at 12700 rpm resulted decline in the extraction efficiency owing to the rupture of the membrane, because of the quick coalescence of droplets made the film layers unable to withstand the impact force, causing the emulsion breakage. Suleiman et al, [35], observed similar behavior. At high homogenizing speed of 19700 rpm, a thick emulsion and emulsion is formed containing big emulsion droplet which reduces the emulsion stability.…”

Reuse of waste cooking oil (WCO) as diluent in green emulsion liquid membrane (GELM) for zinc extraction

“…Unfortunately, each of these methods possesses drawbacks. On the other hand, liquid membrane is regarded as a green alternative (Kumar et al, 2018b) due to its low-cost feature in terms of energy utilization, compared to a pressure-driven membrane and it works relatively fast, with less equipment and chemical consumptions (Björkegren et al, 2015;Othman et al, 2019;Raja Sulaiman et al, 2014). There are several con gurations of liquid membrane reported to date but the focus of this work is the emulsion type.…”

“…It is a promising technique in the separation process of heavy metal contaminants due to its ability to combine extraction and stripping processes in a single step simultaneously. Emulsion liquid membrane (ELM) able to recover a very low concentration of heavy metals from an aqueous solution, even at a concentration of lesser than 10 ppm (Ahmad et al, 2011;Raja Sulaiman et al, 2014). This is possible due to the high interfacial area per unit volume provided by the large number of small droplets formed in the double emulsion (Valenzuela et al, 2010).…”