Evaluation of polymeric hydrophobic membranes for the purification of chlorine produced in electrochlorination processes using seawater desalination brines
Tutor / directorCortina Pallás, José Luís
Document typeMaster thesis
Rights accessOpen Access
The purification of chlorine from brines using polymeric hydrophobic membranes has been evaluated in this work. The objectives have been both to determine the suitable membrane to efficiently transport chlorine and the best operational conditions. Fluoride based polymeric membranes like Polytetrafluoroethylene (FGLP) and (Polyvinylidene fluoride (GVHP) have been selected. Mass transport properties of these membranes have been determined experimentally using flat-sheet membrane modules. The transported chlorine is stabilized in the receiving phase using concentrated solutions of NaOH. The experimental studies have been carried out with under different initial total chlorine concentration and pH. It was determined that most efficient membrane for purification of chlorine is GVHP as provided higher permeability (3.11x10-3m.s-1) values in all operating conditions; the mass transfer coefficient for the membrane varied from 7.59x10-7 to 5.31x10-5cm.s-1 while for the FGLP membrane varied from 1.27x10-6 to 1.90x10-5cm.s-1. The membranes showed to be resistant to the oxidizing conditions of these solutions as demonstrated by FT-IR and SEM-EDS. Chlorine speciation is affecting the strongly the mass transport properties and for example HOCl species are transported in major proportion when the pH of the feed solutions is higher than 2 than the Cl2 species. The experimental results demonstrated the strong influence of the membrane permeability to chlorine species on the pH of the feed solution.