Preparation Of Bi-based Photocatalysts With Controllable Wettability And Its Removal Of 17α-ethinylestradiol

17α-ethynylestradiol（EE2）is a widely used synthetic estrogen,at present,EE2has been detected in drinking water,surface water,groundwater,and other water bodies.It brings serious threat to biology and human beings by interfering with the endocrine system,nervous system and immune system of animals and plants and human beings.Therefore,the widespread existence of EE2 in water and its incalculable harm make people urgently look for the efficient EE2 removal methods.Photocatalytic technology is simple,efficient and green,and has attractive application prospects.Because photocatalytic degradation is a surface reaction,the surface wettability of photocatalyst will greatly affect the adsorption of pollutants in water and the desorption of degradation products,thus affecting the catalytic performance of materials.Therefore,proper regulation of the surface wettability of photocatalyst has an important impact on its photocatalytic degradation performance.In this paper,two kinds of photocatalysts,BiVO₄ and BiOI,were prepared by hydrothermal method.Then,different doses of 3-aminopropyltriethoxysilane（APTES）,hexamethyldisilazane（HMDS）and polydimethylsiloxane（PDMS）were used to modify them respectively in water bath to prepare BiVO₄and BiOI photocatalysts with controllable wettability.XRD,XPS,SEM,TEM,BET,UV-Vis DRS,FTIR and WCA were used to characterize the phase composition,chemical state,morphology,specific surface area,optical properties,characteristic chemical bond and water contact angle of the photocatalyst.The photodegradation of EE2 with three kinds of modified photocatalysts under visible light was investigated,and the reasons for the enhancement of the catalytic performance of the modified photocatalysts were discussed.The details are as follows:1.BiVO₄ photocatalyst was prepared by hydrothermal method,and then modified by 3-aminopropyltriethoxysilane（APTES）to prepare BiVO₄photocatalyst with the controllable wettability.Then optimized conditions for preparing the materials were as follows:the optimal hydrothermal reaction time of BiVO₄synthesis was 24 h,and the optimal modified dose of preparing APTES modified BiVO₄was0.70 m L.BiVO₄and a series of modified BiVO₄with different APTES doses were applied to the catalytic degradation of 3.0 mg/L 17α-ethynylestradiol（EE2）.Compared with unmodified BiVO₄,the WCA of BiVO₄modified by APTES increased,when the WCA of BiVO₄modified by APTES was adjusted to the range of13.2°～25.3°,photocatalytic activity of the modified BiVO₄was better than that of the original BiVO₄.WCA of opitimal photocatalyst BiVO₄（0.70 APTES）was 17.7°,the total removal rate of EE2 was 91.27%after 180 minutes of visible light irradiation,while the total removal rate of unmodified BiVO₄is only 59.34%.The reaction rate constant of BiVO₄（0.70 APTES）was 2.78 times of that of unmodified BiVO₄.2.BiOI photocatalyst was prepared by hydrothermal method,and then modified by different doses of HMDS and PDMS to prepare two kinds of BiOI photocatalyst with controllable wettability.Then optimized conditions for preparing the materials were as follows:the optimal hydrothermal reaction temperature,the optimal hydrothermal reaction time,the optimal modified dose of HMDS modified BiOI and PDMS modified BiOI were 180°C,12 h,1.00 m L and 0.20 m L,respectively.BiOI and a series of BiOI modified by HMDS and PDMS were applied to the catalytic degradation of 3.0 mg/L 17α-ethynylestradiol（EE2）.Compared with unmodified BiOI,the WCA of BiOI modified by HMDS and PDMS increased,when the WCA of BiOI modified by different dose of HMDS and PDMS was adjusted to the range of23.9°～33.7°and 33.5°～87.0°,the photocatalytic activity was better than that of unmodified BiOI.The WCAs of the optimal photocatalysts BiOI（1.00 HMDS）and BiOI（0.20 PDMS）were 29.7°and 47.8°,respectively,after visible light irradiation of28 minutes,the total removal rate of EE2 of BiOI（1.00 HMDS）and BiOI（0.20PDMS）was 98.85%and 98.72%,respectively,while the total removal rate of unmodified BiOI was 85.01%.The reaction rate constants of BiOI（1.00 HMDS）and BiOI（0.20 PDMS）were 2.33 and 2.15 times higher than those of unmodified BiOI,respectively.