Preparation of inorganic nanocomposite coagulant and its application in oilfield sewage treatment

Carbon nanotubes (CNTs), as a new type of carbon material with complete molecular structure, have great application potential in the field of nanocomposites. In this study, carbon nanotubes were first surface modified to give them good hydrophilicity. Subsequently, the nanocomposite coagulant (PASS-T) with different modified CNTs (m-CNTs) contents was prepared by alkaline titration method. The CNT, m-CNT, PASS and PASS-T were characterized by FTIR, XRD and XRF. Then the coagulant was applied to oily sewage, and the coagulation results showed that the PASS-T (0.1%) had the best oil reduction rate (92%) and turbidity reduction rate (97%). Appropriate addition of m-CNT can increase the local concentration of coagulant at the molecular level, making the flocs of oily sewage larger. It can be found by SEM that PASS-T produces large and knotted flocs in oily sewage. Finally, the residual turbidity and oil removal rate of the different coagulants were statistically analyzed.