Diclofenac extraction from aqueous solution by an emulsion liquid membrane: Parameter study and optimization using the response surface methodology

Abstract

Abstract In this work, extraction of diclofenac (DCF) ions from aqueous solution by emulsion liquid membrane (ELM) was studied. The ELM process by experimental work and response surface methodology (RSM) based on central composite design (CCD) was carried out. The liquid membrane phase of the ELM consisted of tetrabutylammonium bromide (TBAB) as a carrier, Span 80 as a surfactant, dichloromethane (CH 2 Cl 2 ) as diluent and sodium hydroxide (NaOH) solution as the internal phase. The transport of DCF ions from the aqueous solution was evaluated from yield of extraction as the analytical response. The process parameters such as surfactant concentration, carrier concentration, extraction time, feed concentration, treat ratio (volume ratio of the external phase to the emulsion phase), and agitation speed were optimized. The contours and 3D response surfaces of DCF extraction efficiency were obtained. A quadratic polynomial model was fitted with a high coefficient of determination (R 2 = 0.9946, n = 32) to predict the extraction yield of DCF. The comparison between the values, experimentally optimized and RSM optimized, indicated that all values were in good agreement with each other. The results of RSM showed that the favorable conditions obtained for the extraction process were at feed concentration of 82 ppm, carrier concentration of 0.04 M, surfactant concentration of 2% (vol/vol), agitation speed of 238 rpm, treat ratio of 2.2 and extraction time of 6 min. At these conditions, the maximum extraction of the DCF was 99.65%. The prepared ELM can effectively be used as a new method for treatment of pharmaceutical wastewater due to its high extraction efficiency with low required time.