SEM-EDX studies of SiO2/PVDF membranes fouling in electrodialysis of polymer-flooding produced wastewater: Diatomite, APAM and crude oil

This study focused on the characterization of SiO2/PVDF anion-exchange membrane (AEM) fouling in electrodialysis for the treatment of polymer-flooding produced wastewater containing suspended solid (SS), anionic polyacrylamide (APAM) and crude oil in Daqing oilfield in China. Scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis was used to investigate the membrane surface morphology and examine the chemical composition of the fouled membrane surface. The morphological study showed only a small amount of cake layers located on the external surface of the SiO2/PVDF AEMs fouled by SS and APAM, respectively. Meanwhile, the contaminants adsorbed on the membrane surface and in the membrane pores were relatively more in the presence of crude oil. It was also found that the SiO2/PVDF membranes exhibited better antifouling capacity than PVDF membranes indicated in the membrane fouling behavior and desalination time. EDX analyses revealed that the foulants on the membrane surfaces comprised not only organic substances but also inorganic elements.