A full factorial design‐based desirability function approach to investigate the transport of Ni2+, Co2+, Cr3+ and Zn2+ through polymer inclusion membranes

Abstract

In the present study, the full factorial design methodology was used to investigate and optimize the operating conditions of a membrane process involving polymer inclusion membranes (PIMs), for the competitive removal of Ni2+, Co2+, Cr3+ and Zn2+ from aqueous solutions. The effects of three parameters: initial concentration of metals (X1), extractant content (X2) and membrane thickness (X3) were investigated on the matter fluxes crossing the PIMs (Ji), the amount of metal ions fixed within them (τf), and transferred through them (τt). The study revealed that: (1) the selectivity order of metal ions crossing the synthesized PIMs is: Zn > Ni > Cr > Co, (2) the order of significance of the effects is: X1 > X2 > X3, (3) X1 and X2 have positive effect on J, τf and τt while X3 has a negative effect on J and τt, and (4) the estimated models for the responses fit the experimental data adequately (deter-mination coefficient: R2 = 84.70%–99.99%; standard deviation: SD = 0.0021 – 1.58). The desirability function-based optimization indicated that: Jmax and τtmax are obtained for X1max (200 ppm), X2max (60% w/w) and X3min (50 µm), for a desirability value of 0.93 and 0.81, respectively, while τfmax is obtained for X1max, X2max and X3max (65 µm), for a desirability value of 0.93.