Preparation Of Cyclodextrin Modified Titanium Dioxide And Photoc Atalytic Degradation Of Dyes

In this study,according to the basic properties of titanium dioxide catalyst and photocatalytic principle,cyclodextrin derivatives were used to improve the adsorption ability of dyes,so as to modify titanium dioxide.Titanium dioxide photocatalyst modified by cyclodextrin derivatives was prepared by wet chemical method.The carboxyl group of modified cyclodextrin can easily bind to titanium dioxide,and the cyclodextrin cavity can bind to the characteristics of dyes,so as to improve the efficiency of photodegradation of dyes.1.First of all,the Appel-Lee reaction was used to successfully synthesize per-[6-deoxy-6-bromine]-β-cyclodextrin,per-[6-deoxy-6-bromine]-y-cyclodextrin;Subsequently,Br-β(γ)-CD was used as an intermediate to undergo a nucleophilic substitution reaction with thioproponic acid and thioacetic acid to synthesize the per-[6-deoxy-6-sulfur carboxy-methyl]-β-cyclodextrin,per-[6-deoxy-6-sulfur-carboxymethyl]-γ-cyclodextrin,per-[6-deoxy-6-sulfur-carboxymethyl]-β-cyclodextrin and per-[6-deoxy-6-sulfur-carboxymethyl]-y-cyclodextrin were characterized by nuclear magnetic resonance and infrared spectros-copy,and the results showed that many cyclodextrin derivatives were successfully prepar-ed.2.Titanium dioxide TiO2 with high catalytic activity and modified per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin-titanium dioxide catalyst were successfully prepared by wet chemical method under controlled preparation conditions.The morphology was characterized by Scanning Electron Microscope,X-ray powder diffraction,infr-ared Spectro-scopy and Raman Spectrum.The results show that that TiO2 present not only anatase phase but also a small amount of plate titanite crystal,and per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin-titanium dioxide was the highest catalytic activity of anatase with high crystallini-ty.The specific surface area and void volume of per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin-titanium dioxide were larger through nitrogen adsorption and desorption measure-ment.3.The degradation ability of titanium dioxide,per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin-titanium dioxide and Degussa P25 photocatalysts to Rhodamine B dyes was studied under photogenic conditions.The light experiment results show that per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin-titanium dioxide as a photocatalyst can degrade Rhoda-mine B solution 30 min under light,and the degradation rate is 99.7%,which is higher than titanium dioxide(degradation rate 79.3%)and P25(degradation rate 71.1%).The reason is that the addition of per-[6-deoxy-6-thio-carboxyethyl]-β-cycloddin improves the adsorption ability of the catalyst to the dye,so that the dye is more adsorbed on the surface of titanium dioxide particles,thereby improving its photocatalytic ability.The degradation efficiency of eight common dyes,such as methylene blue,indigo red,tetrachlorotetraiodine luciferin and 8-hydroxy-1,3,6-pyrene tri-sodium tri-sulfonic acid,was investigated by light.It is found that photocatalytic process is the process of photo-sensitive oxidation of dyes,and the mechanism and conditions of dye sensitization are briefly introduced.The photo-sensitive oxidation mechanism will help to improve the overall efficiency of photocatalysis and make photocatalysis of visible light dyes more feasible.