## 4 Conclusions  
For effective and reliable oil/saltwater separation, a novel type of nanostructured TNF/CNF membrane was presented in this study. The novel membranes were made of ultralong titanate and carbon nanofibers. The membranes show high hydrophilicity and high oil repellence, which render the excellent anti-oil-fouling property. The membranes feature an interconnected porous structure, which enables the high water permeation flux (1520 LMH/bar) at low operating pressure. The novel TNF/CNF membrane exhibits high oil removal above 99.1%, oil content in the permeate below the US environmental discharge limit (42 ppm). Most importantly, even after multiple cycles of reuse in environments with various salinities, the performance with oil rejection rate and water flux can be well maintained. This new membrane has great potential to treat oil/gas field production water and marine oil spills due to its durability, separation efficiency, fouling resistance, and inexpensive fabrication. The future work for this research may focus on the prototyping of the new membranes at a larger scale to further demonstrate its industrial applicability.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13116792/s1](https://www.mdpi.com/article/10.3390/app13116792/s1)]([https://www.mdpi.com/article/10.3390/app13116792/s1](https://www.mdpi.com/article/10.3390/app13116792/s1)), Figure S1: Optimization process for the deposition of titanate nanofibers and silica solution with 15 different compositions; Figure S2: **(a)** Water Flux using TNF/CNF membrane using different loading of TNF and CNF. **(b)** Percentage of oil rejection using TNF/CNF membrane using different loading of TNF and CN; Figure S3: Long term acidic stability test (0.1 M HNO3, PH-1). **(a)** Performance test (oil rejection rate) and water flux (LMH/bar) of the TNF/CNF mem-brane after different time interval exposure to acidic environment. **(b)** Oil concentration in the permeate different time interval exposure to acidic environment; Figure S4: Long  
Figure 12: **(a)** The performance of the membrane after reusing the membrane 10 cycles: **(a)** oil rejection (ppm) and water flux (LMH/bar)) of the TNF/CNF membrane. **(b)** Oil concentration in the permeate after reusing the membrane 10 cycles.  
term basic stability test (0.1 M NaOH, PH-13). (**a**) Performance test (oil rejection rate) and water flux (LMH/bar)) of the TNF/CNF mem-brane after different time interval exposure to basic environment. (**b**) Oil concentration in the permeate different time interval exposure to basic environment.  
Conceptualization, R.E., Z.L. and S.A.; Methodology, R.E. and Z.L.; Validation, R.E. and Z.L.; Investigation, R.E. and Z.L.; Resources, R.E.; Writing--original draft, R.E. and Z.L.; Writing--review and editing, R.E., Z.L. and S.A. All authors have read and agreed to the published version of the manuscript.  
This article has no external funding.  
Not applicable.  
The authors would like to acknowledge the contribution of the Core Laboratory of Qatar Environment and the Energy Research Institute (QEERI) for the SEM, XRD, and AFM characterizations of the materials.  
The authors declare no conflict of interest.