In situ grown, super-hydrophilic and multifunctional hydroxyapatite composite membrane for oil–water separation

In this paper, a method of growing SiO2 on hydroxyapatite in situ and depositing it into polydopamine-modified MCEM membrane was reported to prepare super-hydrophilic underwater super-oleophobic coatings. The results showed that the hydrophilic properties of SiO2, the hydroxy-rich structure of hydroxyapatite and the synergistic action of polydopamine made the membrane have excellent hydrophilicity. The modified HAP@SiO2/PDA coating membrane not only had excellent mechanical properties, but also had good oil and water selectivity. At the same time, the membrane separation flux of light oil can reach 3000 L/(m2·h), and the oil discharge rate of heavy oil can reach 98.95%. More importantly, the membrane can remove 90.90% of the actual oilfield wastewater. As a result, HAP@SiO2/PDA coatings can effectively treat a wide range of oily wastewater and demonstrate attractive separation capabilities.