Adsorption Properties of Triglycerides and Long Chain Fatty Acid on UF Membranes: Effect of Membrane Hydrophobicity and Feed Chemistry

Abstract

One of the major drawbacks for the successful of Ultrafiltration (UF) during pretreatment of glycerin-rich solution is membrane fouling due to the deposition of Triglycerides (TG) and Fatty Acids (FA). The aim of the present study is to contribute to the better understanding of fouling by TG as well as TG-FA mixtures and their adsorption properties on UF membrane. Additionally, another significant part of this study was the elucidation of the solute-solute interaction in the feed solution. Two UF membranes were used with the membrane materials made from Polyethersulfone (PES) and Polyvinylidenefluoride (PVDF) with MWCO between 5, 20 and 25 kDa for PES, while 30 kDa for PVDF. Static adsorption of TG and TG-FA were investigated at the solution pH values of 3, 7 and 10; for different MWCO. The behavior of solute adsorption was investigated by taking into account the thickness of fouling layer, the percentage of pore reduction and the water RFR. It was observed that the addition of TG into the glycerin-rich solutions caused a significant relative flux reduction (RFR) than TG-FA and this was probably due to the formation of macromolecule on the membrane surface. The RFR was also dependent on the solution chemistry. Adsorption behavior onto membrane surfaces were analyzed by contact angle and SEM images. Overall results revealed that PES membrane exhibited severe fouling and much larger water RFR than PVDF due to its hydrophobicity and surface roughness.