Optimization of lactic acid pertraction using liquid emulsion membranes by response surface methodology

Abstract

The present work deals with the optimization of the conditions for the pertraction of lactic acid from aqueous solution using liquid emulsion membrane. A central composite rotatable design was employed to study the effect of stripping solution (Na2CO3) concentration (1.0–5.0% w/v), ratio of strip to membrane phase (Vs/Vm) (1.0–5.0), ratio of volume of feed to emulsion (Vf/Ve) (1.0–5.0) and contact time (2.0–15.0min) on the pertraction. The response surface models with high coefficients of determination values (R2=0.95) were fitted to the experimental data, which indicated that the polynomial response models fitted well for describing the % pertraction of lactic acid as well as % membrane phase recovery. Based on the design, the optimal conditions for obtaining higher pertraction were stripping phase (Na2CO3) concentration ranging from 1.58% to 3.46% w/v, ratio of strip to membrane phase and the ratio of volume of feed to emulsion 2.0, contact time ranging from 12.11 to 14.71min. The graphical optimization of superimposed contour plots fulfilled the conditions to obtain % lactic acid recovery (Y1)⩾95% and % membrane phase recovery (Y2)⩾80%. The study demonstrated that response surface methodology can be utilized for deriving the optimum conditions for pertraction of lactic acid from aqueous solutions.