Investigation of the kinetics and isotherms of the uptake of Bi(III) by a poly(vinyl chloride) inclusion membrane containing di-(2-ethylhexyl)phosphoric acid

The present communication aims to describe the kinetics and isotherms of the extraction of bismuth(III) from sulfate solutions by a plasticizer-free polymer inclusion membrane composed of 50 %w/w polyvinyl chloride (PVC) as the base polymer and 50% w/w di-(2-ethylhexyl)phosphoric acid (DEHPA) as the carrier. The isotherms of the process are also studied by applying Langmuir, Freundlich and, Dubinin–Radushkevich (D–R) models. The analysis of the data showed that Langmuir isotherm can suitably describe the experimental data. The interpretation of the process kinetics was done by fitting the experimental data to the different kinetic models (i.e., pseudo-first order, pseudo-second order, intra-particle diffusion, power function, and Elovich models). Among these models, the pseudo-second order model described well the experimental data.The kinetic and isotherm studies revealed that the sorption of Bi(III) by the optimized membrane is a chemisorption process.