Mechanistic fouling study of Hybrid imidazolium-based ionic liquid membrane during emulsified oil removal from oily wastewater; oil type effect

To overcome the strict discharge effluent regulations of oily wastewater, the treatment with membranes has a good perspective. In this work, [C12mim][Cl] ionic liquid was induced into the polyether sulfone membrane to improve membrane hydrophilicity and anti-fouling resistance. To reveal the membrane fouling type, the permeate flux of the membrane was modeled according to Hermia's equations and combined equations driven from four main fouling mechanisms equation. In addition, to develop a proper interpretation and fully new insights mechanisms, the elemental and topographical analyses, and chemical surface characterizations using FESEM, EDS MAPPING, AFM, FESEM, Zeta analyses, and contact angle and interfacial tension measurements were performed on the four different oily wastewaters and the membrane. So, the impact of interfacial tension, wettability, mean particle size, particle size distribution (polydispersity index), zeta potential, acidic and basic nature of oil, and the properties of polar fractions of oil including the asphaltene and resin concentrations and their weight percent of polar heteroatoms were thoroughly examined. The results revealed a reduction in permeate flux as the API gravity was reduced due to the particle size of the oily wastewater emulsion increased. Consequently, the wettability of the membrane altered towards a more oil-wet state leading to a reduction in the roughness of the membrane surface. The attachment and cover of the surface mainly by the acidic component of the oil with a higher affinity to attach the oxygen element of the membrane were proposed as the dominant mechanism of cake layer fouling.

Automated summary

This study investigates the use of an ionic liquid to improve the hydrophilicity and anti-fouling resistance of a polyether sulfone membrane for the treatment of oily wastewater. By modeling the membrane's permeate flux and analyzing the elemental and surface properties of the wastewater and membrane, the researchers were able to understand the mechanisms of membrane fouling caused by the oily wastewater.