Ceramic membrane fouling during ultrafiltration of oil/water emulsions: roles played by stabilization surfactants of oil droplets.
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.
†State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China.
Dongwei
D
Lu
‡Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal 4700, Kingdom of Saudi Arabia.
Tao
T
Zhang
†State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China.
Jun
J
Ma
D002516:Ceramics / Q000737:chemistry*; D004655:Emulsions; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D009821:Oils / Q000737:chemistry / Q000302:isolation & purification*; D013501:Surface-Active Agents / Q000737:chemistry; D014462:Ultrafiltration / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D004655:Emulsions; D008567:Membranes, Artificial; D009821:Oils; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical