Photocatalytic Removal Of Pollutants Such As BPA By ?-cyclodextrin Modified Titanium Dioxide Materials In Wastewater

Organic pollutants such as drugs,antibiotics,and endocrine disrupting chemicals in water have an increasing impact on human life,which need to be removed efficiently.Compared with physical and biological treatment technologies,chemical methods have significant advantages in removing organic pollutants.Photocatalytic technology has shown great potential in wastewater treatment.However,TiO2 has a high electron-hole recombination rate,and it's too small to be separated as well.Therefore,the practical application of TiO2 photocatalytic method was limited.Aiming at solving the limit of TiO2,TiO2 nanotubes were prepared by hydrothermal method in this paper.Using industrial nano-sized TiO2(P25)and TiO2 nanotubes as the basic material,the effects of different modification methods on photocatalytic ability are investigated as well.(1)Hollow TiO2 nanotubes(TNT)were prepared by hydrothermal method.The conditions for stable preparation of TiO2 nanotubes were obtained by controlling the reaction temperature,reaction time,and material ratio.TiO2 nanotubes prepared by hydrothermal method were controllable and have stable properties,which were also easier to separate than P25.(2)Modified CM-?-CD-P25 was prepared and used to remove organic pollutants in wastewater.The concentration of Bisphenol A(BPA),Bisphenol S(BPS),carbamazepine(CBZ),2,4-dichlorophenol(2,4-DCP),paracetamol(4-AP),phenol(Phenol)and sulfonamide(SA)can be removed 91.6%,97.6%,100%,91.0%,99.5%,71.9%,and 97.1%in 1 hour,respectively,with the initial concentration was 20 mg/L.Au-P25,prepared by photodeposition method,has inferior photochemical properties comparing with CM-?-CD-P25.The photocatalytic mechanism of CM-?-CD-P25 system was proved through free-radical capture,EPR and LC-MS.After ultraviolet light excites P25 to generate electrons,the electrons attack water molecules to generate ·OH,which is used to attack pollutants.On the one hand,CD on the surface accelerates the electron transfer rate,and on the other hand,it provides a hydrophobic cavity.By capturing organic pollutants,the ROS produced by photocatalysis can be used more effectively.(3)Modified CM-?-CD-TNT was prepared and used to remove organic pollutants.The concentration of Bisphenol A(BPA),Bisphenol S(BPS),carbamazepine(CBZ),2,4-dichlorophenol(2,4-DCP),paracetamol(4-AP),phenol(Phenol)and sulfonamide(SA)can be removed 96.0%,99.7%,96.1%,97.5%,97.3%,91.4%and 97.0%in 2.5 hours,respectively,with the initial concentration was 20 mg/L.CM-?-CD can also significantly improve the electron transport on the surface of TNT.The photocatalytic mechanism of CM-?-CD-TNT system was proved through free-radical capture with low dissolved oxygen.Different from P25 system,the electrons firstly attack the microbubbles captured on CM-?-CD-TNT,which turn O2 to ·O2-to degration organic mico-pollutants.CD not only accelerates the rate of electron transfer and captures organic pollutants,but also captures hydrophobic microbubbles.