Iono-molecular Separation with Composite Membranes. VII. Nitrophenols pertraction on capilary polypropylene S-EPDM composite membranes

Abstract

In the present paper the authors study the pertraction of the nitrophenols through the immobilization using chemical reaction in receiving phase, using a laboratory installation conceived by the Group of Membranes, Materials and Membrane Processes within University Politehnica of Bucharest. This installation was developed using liquid synthetically solutions, through composite membranes having a matrix of capillary polypropylene and inclusions of ethylene propylene diene terpolymer sulfonic acid (S-EPDM) or sulfonated ethylene-propylene-diene terpolymer (S-EPDM). The results were follow: The permeation through the compartments of the system with composite S-EPDM membranes is limited, in the aqueous phases, by the solubility of the compound about to be separated, namely the membrane itself, and subsequently by its diffusion from the feed compartment to the collection compartment. The chemical reaction of immobilization, in the receiving phase, can be achieved in several variants (neutralization, esterification, complexation, oxidation, coupling, oxidative degradation); The biggest flows are obtained in compensation of the o-nitrophenol with ferric ions and then, in acetylation of the o-nitrophenol with acetic anhydride. However, we can emphasize that the derivatization of the o-nitrophenol through complexation and acetylation reactions requires its use as such in later processes, unlike the neutralization, for which the nitrophenolate ion easily frees the nitrophenol for future applications;For the neutralization reaction, the removing coefficient grows with decreasing of pKa value of the nitrophenols. For complexation reaction, the most favorable results were obtained for o-nitrophenol - over 66%;The coupling reaction of the o-nitrophenol, in the receiving phase, with the diazonium chloride of the p-nitroaniline and hydrogen peroxide 3% in sulfuric acid 20%, respectively, concludes with the exhaustion of the source phase, after 24 hours of operation.