Preparation Of Ultrafiltration Membranes And Application On Oil Degumming

Hydration degum methods are traditionally used in the plant oil degumming process,in which as heating is essential, high energy consumption may be resulted, this method andthe process route is complicated. As the result, new techniques and methods which canovercome the shortcomings mentioned above are the focuses of researchers. Ultrafiltrationmembrane technology is one of the new methods, which has many advantages as followed:mild process conditions, low energy consumption, no poisonous and harmful substance,easy operation, no oil waste, environmental friendly. In this study, the new ultrafiltrationmembranes were prepared and applied in oil degumming process.The cellulose acetate ultrafiltration membranes were prepared with cellulose acetateby means of the phase transformation technique. Cellulose acetate quality score,evaporation time, coagulation bath temperature, defoaming time, mixing temperature,defoaming temperature and mixing time were studied in the experiment. The celluloseacetate ultrafiltration membranes were applied in the degumming of rapeseed oil,meanwhile the oil flux of membrane and phospholipids interception rate were determined.It was revealed that the chosen condition was13%cellulose acetate quality score,35sevaporation time,20℃coagulation bath temperature,12h defoaming time,40℃mixingtemperature,75℃defoaming temperature,8h mixing time. At the0.2MPa, membrane fluxwas45.90kg/(m2··h), phospholipids interception rate was88.2%.Polysulfone （PS） ultrafiltration membrane was prepared by phase transformationtechnique and the PS membrane materials，Polyethylene pyrrole（PVP）as additive,N,N-dimethyl acetamide (DMAC) as solvent.Experiments focused on the oil/hexanemixture flux and rejection which was affected by total raw material quality score, additives,evaporation time, coagulation bath temperature, mixing temperature, defoamingtemperature and mixing time. Experimental results showed that: when PS content was14％, PVP content was3%, evaporation time was50s, coagulation bath was30℃, the mixingtemperature was65℃, defoaming temperature was45℃and mixing time was10h, thatpolysulphone showed good performance.When the Pressure is0.2MPa,the flux of30％oil/hexane solution is45.4kg/(m2·h), the rejection reached to89.9％。PS/CA mixed ultrafiltration membrane was successfully prepared by means of phasetransformation technique with PS and CA as raw materials. The effects of raw materialsratio, total raw material content, additives, evaporation time, coagulation bath temperature,mixing temperature, defoaming temperature and mixing time were investigated on the fluxand absolet removal rating.of rapeseed oil/hexane mixture. Through the experiment theoptimal process conditions were got: The ratio of PS and CA1:5, membrane materialscontent14%, and no additives, evaporation time10s and coagulation bath temperature20 ℃, mixing temperature70℃, defoaming temperature30℃and mixing time6h. The PS/CAultrafiltration membrane application in oils degumming were also introduced: the flux was38.9kg/(m2·h), rejection was88.7%for30%rapeseed oil/hexane mixture at roomtemperature and pressure0.2MPa.The above three ultrafiltration membranes were applied in degumming rapeseed oil.Performance indexes which were average pore size, membrane porosity, counter pollutionability and resistance to acid and alkali were measured. Influences of operation time,operation temperature, operation pressure and initial oil concentration on permeate fluxand decolorization rate were evaluated. Flux and degumming rate were compared amongthree kinds of membranes.