Simulation of fouling mechanism in separation of oil/water emulsion using PVDF ultrafiltration membranes

摘要

An empirical model based on logistic equation coupled with gel polarization/film mathematicalmodel based on cake filtration theory, have been developed in the present study. Unlike the factors need to bedetermined in convection-diffusion model, the factors in this empirical model were easier to achieve. In case ofcontinuous stirred ultrafiltration, the deposited solutes are allowed to build up over the membrane indefinitely,along with continuous back transport of deposited solutes into bulk by the turbulence created by stirring action.However, solutes can deposit on the membrane surface easily in non-stirred process, which turned into the gellayer. To simulate this gel polarization process, the difference value between the two processes was defined asthe flux decline caused by gel. The results shown that this gel formation simulated by logistic model with a R2value 0.9941, which was reliable, and a R2value of 0.9971 for gel elimination simulation. However, both cakefiltration models and convection-diffusion model were not enough to simulate this process, that not onlybecause the parameters were hard to determine, but the R2value were also too low to simulate this processaccurately. Thus, this empirical model based on logistic equation has been found to predict the formation andelimination of polarized layer resistance reasonably well once the three parameters (initial, middle and finalvalue of flux) describing the model were known along with the operating condition. Moreover, surface andcross-sectional morphology of membrane was investigated by SEM to make an advanced certificate of this UFmechanism.