The effects of salt concentration and foulant surface charge on hydrocarbon fouling of a poly(vinylidene fluoride) microfiltration membrane

• Published in: Water research (Oxford) Vol. 117; pp. 230 - 241
• Main Authors: He, Zhengwang, Kasemset, Sirirat, Kirschner, Alon Y., Cheng, Yu-Heng, Paul, Donald R., Freeman, Benny D.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.06.2017
• Subjects: DLVO model; Emulsions; Filtration; fluorides; fouling; Fouling propensity; Hydrocarbons; Ionic strength; Membrane fouling; Membranes, Artificial; microfiltration; Oil emulsion; oils; prediction; salt concentration; sodium chloride; surface interactions; Surface Properties; surface tension; Zeta potential; DLVO model; Fouling propensity; Zeta potential; Ionic strength; Membrane fouling; Oil emulsion
• ISSN: 0043-1354; 1879-2448; 1879-2448
• DOI: 10.1016/j.watres.2017.03.051

The effects of inorganic salts and organic hydrocarbons on membrane fouling are often investigated independently. However, in many cases, these foulants are commonly found together, and such mixtures are rarely the subject of fouling studies. In this study, crude oil-in-water emulsions were formulated at three different added NaCl concentrations, 0, 10-3 and 10−1 M. Surface properties, such as surface tension and surface charge, of these emulsions and a poly(vinylidene fluoride) (PVDF) microfiltration (MF) membrane were characterized. The Derjaguin-Landau-Verwey-Overbeek (DLVO) model was utilized to simulate membrane-oil droplet and oil layer-oil droplet surface interactions. The DLVO model qualitatively predicted increasing fouling propensity with increasing emulsion salt concentration. The PVDF MF membrane was challenged with crude oil-in-water emulsions in constant permeate flux crossflow fouling tests to characterize the fouling propensity of the various emulsions, and the results were consistent with the model predictions. •Crude oil-in-water emulsions were formulated at various salt concentrations.•Foulant zeta potential decreased with increasing salt concentration.•DLVO model was used to simulate short-range interactions.•Model predictions of fouling propensity matched experimental observations.•Electrostatic interactions dominated van der Waals interactions in this study.