Fouling propensity of a poly(vinylidene fluoride) microfiltration membrane to several model oil/water emulsions

Abstract

Laboratory membrane fouling studies are often performed with a single foulant. However, studies comparing the behavior of different foulants using a single membrane are rarely reported. In this study, a poly(vinylidene) (PVDF) microfiltration membrane was challenged with a series of aqueous-based model fouling media, including a suspension of latex beads, as well as soybean, motor and crude oil emulsions, in constant permeate flux fouling experiments. The critical and threshold fluxes were determined for each membrane-foulant pair. Constant permeate flux crossflow fouling experiments were performed at both low and high fluxes. A direct comparison of the fouling propensity of the PVDF membrane to the four fouling media was made. The fouling propensity was evaluated based on threshold flux values and the extent of transmembrane pressure (TMP) increase during constant permeate flux fouling experiments. In this study, the zeta potential of various fouling media correlated with their fouling propensities. The higher the zeta potential, the lower the fouling propensity. The fouling propensity followed the order of: latex beads < soybean oil < crude oil < motor oil. A three-stage TMP profile was observed with high fouling media, such as motor and crude oil emulsions. The TMP increased slowly in the early stage, then increased abruptly, and eventually reached a new pseudo-steady state TMP.

Performances of Continuous Adsorption-Ultrafiltration Hybrid Process for AO7 Dye Removal from Aqueous Solution and Real Textile Wastewater Treatment

“…Effect of PAC dose In simple UF process, the permeate flux decreased drastically since the first minutes of filtration because the size of dye molecules of 300 Da is very smaller than UF membrane weight cut-off of 150 KDa, which induce membrane fouling due to the pore clogging by AO7 molecules in addition to the possibility of the interaction with the membrane surface or into the pores [21].…”

“…The permeate flux is almost stable using the hybrid process (460 L/h.m 2 -400 L/h.m 2 ) whereas a dramatic decrease of flux from 520 L/h.m 2 to 90 L/h.m 2 was shown when simple UF was applied. This decrease of flux is due to the membrane fouling caused in major part by the pore clogging by the particles having similar or lower size than the mean membrane pore diameter [21]. In hybrid process, the stabilization of permeate flux is due to the limitation of membrane fouling during the period of run.…”

Fouling mechanisms in constant flux crossflow ultrafiltration

“…Equation 18 predicts a linear rise in ΔP with filtration time (cf., Figure S1b in the SI). The assumption that the cake covers the entire membrane surface area cannot be strictly true at very short filtration times, before a cake layer has deposited.…”

“…Pretreated membranes were stored in ultrapure water until use. The pH of the suspension was adjusted to 6 using 8 mL of pH 6 buffer [18] .…”

“…The emulsion was then diluted with another 7 L of DI water. Oil droplets had an average diameter of ~3.4 ± 1.3 µm [18] .…”