## 3 Results and Discussion
### Pure Water Permeability and Antifouling Properties  
Table 1 shows the permeability of the bare Al\({}_{2}\)O\({}_{3}\) and TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membranes for DI water after 2.5 h of filtration. A significant decline in the membrane permeability was observed after depositing a TiO\({}_{2}\) layer on the Al\({}_{2}\)O\({}_{3}\) membrane support. In the absence of UV illumination, the permeability of the Al\({}_{2}\)O\({}_{3}\) membrane was 65.2 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\), which was reduced to 9.9 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\) for the POEM-directed TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane. Such a reduction of the membrane permeability is attributed to the increased membrane resistance against the water flow upon significant reduction of the membrane pore size [20; 21]. However, exposure to UV illumination enhanced the membrane permeability of both membranes. The permeability of the bare Al\({}_{2}\)O\({}_{3}\) membrane and TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane under UV illumination increased to 71.5 and 14.2 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\), respectively. Such a membrane permeability enhancement can be resulted from improvement of the membrane wettability or higher water temperature induced by the UV irradiation [15; 22]. The TiO\({}_{2}\) coating layer can improve surface hydrophilicity under UV radiation due to the production of the hydroxyl groups on membrane [23]. In addition, temperature increase can reduce water viscosity, thereby increasing membrane permeability [22]. To distinguish this effect, membrane permeability measured experimentally was compared with the calculated one by [PERSON]'s equation (Equation (1)) at elevated temperature under UV irradiation at the end of filtration. For the bare membrane under UV irradiation, there is no difference in permeability between measured and calculated value (71.4 vs. 71.5 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\)). This indicates that temperature played a dominant role in determining membrane permeability. For the TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane, membrane permeability measured was 14.2 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\), but the one calculated at the temperature increased by UV irradiation was 10.5 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\). Considering membrane permeability measured with the composite membrane (9.9 L m\({}^{-2}\) h\({}^{-1}\) bar\({}^{-1}\)), contribution of temperature increase to membrane permeability was relatively low compared to the bare membrane. Measurements of water temperature in the permeation line revealed a 5 \(\pm\) 1 \({}^{\circ}\)C increase with bare Al\({}_{2}\)O\({}_{3}\) membrane (about 31 \({}^{\circ}\)C). Increased water temperatures reduce the viscosity, thereby increasing the membrane permeability [22]. For the TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane, the water temperature increase was relatively small as about 3 \({}^{\circ}\)C under UV illumination (about 29 \({}^{\circ}\)C). A possible explanation is that the TiO\({}_{2}\) film on the Al\({}_{2}\)O\({}_{3}\) membrane can support absorbing the UV light and reduce heat dissipation [15; 22]. Figure 7: Atomic force microscopy (AFM) images of the (**a**) bare Al\({}_{2}\)O\({}_{3}\) membrane and (**b**) Poly(oxyethylene methacrylate) (POEM)-directed TiO\({}_{2}\) film on the Al\({}_{2}\)O\({}_{3}\) membrane. Figure 8 compares the effect of the permeate flux on the membrane fouling for both the bare Al\({}_{2}\)O\({}_{3}\) and TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membranes in the absence and presence of UV illumination after filtration for 1 day. In the absence of UV illumination, the extent of the flux decline was lower for the TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane than for the bare Al\({}_{2}\)O\({}_{3}\) membrane. The flux decline was \(\sim\)89.6% lower on the TiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\) composite membrane than on the bare Al\({}_{2}\)O\({}_{3}\) membrane (1.25 vs. 0.13 LMH h\({}^{-1}\)).