INTERACTION BETWEEN THE POLYMER ULTRAFILTRATION MEMBRANE AND PARTICLES OF OIL-IN-WATER EMULSION

Namen raziskave je preučiti vpliv različnih procesnih dejavnikov, na učinkovitost procesa ultrafiltracije oljno-vodne emulzije. Preučili bomo vpliv obratovalnih parametrov kot so tlak, temperatura in pH vrednost ter preizkusili polimerno polietersulfonsko (PES) membrano za čiščenje oljno-vodne emulzije pri procesu čelnega sistema ultrafiltracije. Namen je tudi preučiti medsebojni vpliv zeta potenciala polimerne ultrafiltracijske PES membrane in velikosti delcev oljnih kapljic v emulziji. V raziskavi magistrske naloge smo izvajali čiščenje oljno-vodne emulzije z ultrafiltracijo pri različnih obratovalnih parametrih. Preverili smo učinkovitost zadržanja delcev na površini PES membrane med čiščenjem oljno-vodne emulzije. Pri merjenju zeta potenciala smo ugotavljali stabilnost oljno-vodne emulzije ter vpliv pH vrednosti na zeta potencial PES membrane. Rezultati raziskave so pokazali, da čelna tehnika ultrafiltracije ni najbolj primerna metoda za čiščenje oljno-vodne emulzije zaradi številnih zamašitev PES membrane, tako ireverzibilnih kot tudi reverzibilnih, ki so posledično znižale gostoto volumskega toka permeata. Ugotovili smo, da je PES membrana uspešno zadržala večino delcev oljnih kapljic med ultrafiltracijo, vendar se je zaradi hidrofobnega značaja močno mašila in je ni bilo možno očistiti do te mere, da bi bila primerna za nadaljnjo uporabo. Ugotovili smo, da ima pH vrednost največji vpliv na zeta potencial zaradi interakcij med negativno nabito PES membrano in negativnimi oljnimi kapljicami, zato je pri pH=9 možen najlažji prehod oljnih kapljic skozi membrano in so pretoki višji. Z višjim pH smo dosegli večjo stabilnost oljno-vodne emulzije. Potrdili smo, da PES membrana nima izoelektrične točke in da ima PES membrana negativni zeta potencial v celotnem pH območju, ki med pH 8 in 9 doseže najnižjo vrednost.The purpose of the research was to examine the influence of different factors on the efficiency of the ultrafiltration separation of oil-in-water emulsion. We will examine the influence of operating process parameters such as pressure, temperature and pH value. We will test the polymeric polyethersulfone (PES) membrane for cleaning of oil-in-water emulsion with dead-end ultrafiltration. The purpose is also to examine the interaction between the zeta potential of the polymeric ultrafiltration PES membrane and the particle size of the oil droplets in the emulsion. In the frame of the master\u27s thesis the oil-in-water emulsion was treated by ultrafiltration independance of the different operating parameters. The effectiveness of retention of particles at the PES membrane surface during the cleaning of oil-in-water emulsion was studied. The stability of the oil-in-water emulsion was determined with zeta potential measurement. The influence of pH value on the zeta potential of the PES membrane was investigated. The results showed that the dead-end ultrafiltration is not the most appropriate method for oil-in-water emulsion treatment because of many different types of fouling of the PES membrane, such as irreversible and reversible, and consequently flux permeate declined. We have found that the PES membrane successfully retain most of the particles of oil droplets during the ultrafiltration, but regarding the strong hydrophobic characteristic of the membrane it could not be cleaned to that extend suitable for reuse. We also have found that the pH value has the major influence on the zeta potential regarding interactions between the negatively charged PES membrane and negative charge of oil droplets. At pH=9 oil droplets easily travel through the PES membrane and fluxes are higher. The higher the pH, the higher stability of the oil-in-water emulsion. We confirmed that the PES membrane has no isoelectric point and the membrane has negative zeta potential over the entire pH range. The lowest value of the zeta potential was reached between pH values 8 and 9