Ceramic Membrane Fouling during Ultrafiltration of Oil/Water Emulsions: Roles Played by Stabilization Surfactants of Oil Droplets

Abstract

Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater.

A low-cost mullite-titania composite ceramic hollow fiber microfiltration membrane for highly efficient separation of oil-in-water emulsion

“…Membrane fouling of mullite hollow fiber can be attributed to different mechanisms: the rapid adsorption of oil droplets rapidly on membrane surface and in membrane pores; the partial or complete pore blockage by oil droplets, and the cake layer formation on membrane surface (Lu et al, 2015). In this study, the Hermia model (Huang et al, 2008) (see Section 4, Table S4, SI) was employed to identify the fouling mechanism in the filtration of (O/ W) emulsion.…”

“…With this intension, membrane separation technology (Kri zan Mili c et al, 2013) comes into sight and is playing a very prominent role in treatment of (O/W) emulsion due to its clear advantages (Padaki et al, 2015) such as continuous membrane process operation with simultaneous production of pure water and oil resource (Chang et al, 2014). Unlike their polymeric counterparts (Janknecht et al, 2004;Salahi et al, 2010), the use of ceramic membranes (Lu et al, 2015) offers several benefits, especially in extremely aggressive environments, such as good mechanical performance, easy membrane regeneration by strong acidic or alkaline solution back-flushing (Yang et al, 2012;Deriszadeh et al, 2010). However, currently, application of ceramic membrane technology encounters several problems such as high cost and membrane fouling.…”

Recyclable amine-functionalized magnetic nanoparticles for efficient demulsification of crude oil-in-water emulsions

“…2 Enhanced oil recovery (EOR) processes often further the formation of stable O/W emulsions due to the addition of chemicals, such as surfactants and polymers 1-2 . A great deal of effort has been made to develop effective and economic techniques, such as adsorption, 3 air flotation, 4,5 chemical demulsification, [6][7][8] electrochemical methods, 9 and filtration [10][11][12] to break these stable emulsions. During the produced water treatment, the majority of crude oil can be removed by methods mentioned above.…”

The critical pressure for microfiltration of oil-in-water emulsions using slotted-pore membranes

“…Common antifouling strategies include crossflow filtration, physical or chemical cleaning, surface wettability modification, stabilization by surfactants, and electrostatic repulsion [8][9][10][11][12][13]. More recently, a multicontinuum approach for estimation of the permeation capacity of thin flat membranes with a broad distribution of pore openings was formulated for oil-water emulsions with different droplet sizes and then validated using the experimental data [14,15].…”