Development of a green emulsion liquid membrane using waste cooking oil as diluent for the extraction of arsenic from aqueous solution – Screening, optimization, kinetics and thermodynamics studies

Abstract

Environmental friendly treatment technology was adopted in the present work by employing green emulsion liquid membrane (GELM) for the extraction of arsenic from an aqueous solution. The GELM was composed of used waste cooking oil as a diluent, aliquat 366 as a carrier, span 80 as a surfactant and NaOH as a stripping agent. Waste cooking oil, a nontoxic organic solvent was used as a diluent. Initially, nine parameters, namely, surfactant concentration, carrier concentration, agitation time, agitation speed, pH of the external phase, treat ratio, internal phase concentration, arsenic concentration and volume ratio of organic to aqueous phase were selected and screened by Plackett-Burman design (PBD) for arsenic extraction. Then Box-Behnken design (BBD) was applied using the selected parameters to achieve the optimal condition for the arsenic extraction. The optimum conditions for the maximum removal of arsenic were: Surfactant concentration – 2.3 (v/v %), Carrier concentration – 5.6 (v/v%), Treat ratio – 12, internal phase concentration – 0.92 M, initial arsenic concentration – 100 ppm, O/A ratio – 1. The mechanism of arsenic extraction was also presented. The study on stripping and reuse of the GELM was discussed and recommended that membrane phase might be reused for 6 times. For the optimized factors the maximum extraction of arsenic was estimated as 99.0 %. Kinetic analysis shows that the arsenic extraction by GELM follows first-order reaction. In addition, thermodynamic analysis reveals that the extraction process was an endothermic, and spontaneous in nature.