Surface Molecular Imprinted TiO₂/graphene Photocatalyst And Its Removal Of Bisphenol A In Water

Nowadays,with the development of the industrialization and the abuse of plastics,contamination of endocrine disrupter has been widely caused,and has become a widespread concerned environmental problem in the world along with greenhouse.Titanium dioxide photocatalyst is focused in the semiconductor photocatalyst field for removing the contaminant in wastewater.However,the disadvantages such as a large bandgap,harmful recombination of photogenerated electron-holes,low affinity and poor selection for contaminant,result in a poor performance of TiO₂ in photoactivity in the visible light.In this paper,a new type of composite material is prepared by modification and surface molecular imprinting technique to selective and efficient remove bisphenol A in water.The main experiment contents were as follows:（1）TiO₂/graphene（TiO₂/GR）photocatalyst was synthesized according to a facile solvothermal synthesis method.After that,the surface molecular imprinting technique was used to modify the TiO₂/GR photocatalyst with BPA as the template molecule and OPDA as functional monomers so that MIP-TiO₂/GR photocatalyst was produced.The polymerization of OPDA was initiated by ultraviolet radiation.The characterizations of MIP-TiO₂/GR and the adsorption and catalytic results for BPA of the materials prepared in different experimental stage showed that the molecularly imprinted layer was successfully marked on the surface of TiO₂/GR.（2）For understanding the material comprehensively,the adsorption performance of MIP-TiO₂/GR and NIP-TiO₂/GR was studied for the BPA.Results showed that the adsorption capacity of MIP-TiO₂/GR and NIP-TiO₂/GR were 0.87 mg/g and 0.47 mg/g,when the pH is 6.0,adsorption time is 40 min,BPA initial concentration is 8 mg/L and solvent is water.In addition,selective recognition experiment was performed by using phenol as competitive compounds,and the selectivity coefficients for the experiment were 12.392 and 8.0549,respectively.The kinetics and isotherm studies have shown that the adsorption study for BPA of MIP-TiO₂/GR and NIP-TiO₂/GR matched pseudo-second-order kinetics and Langmuir isotherm model.It concluded that chemical process could be the rate-limiting step in the adsorption process for BPA.Adsorption process was monolayer adsorption and binding sites was uniform distributed on the surface of material.（3）For understanding the material comprehensively,the photocatalytic performance of MIP-TiO₂/GR and NIP-TiO₂/GR was studied for the BPA.Results showed that the catalytic degradation rate for BPA of MIP-TiO₂/GR and NIP-TiO₂/GR were 46.1%and 39.9%,when the pH is 6.0,catalytic reaction time is 180 min and BPA initial concentration is 8 mg/L.The results showed that MIP-TiO₂/GR has good catalytic degradation performance and selectivity.And catalytic kinetic matched pseudo-first-order kinetic model.（4）Reusability of MIP-TiO₂/GR was studied.The results showed that the material had significantly lower removal efficiency after repeated 4 times,and material has a certain reusability performance and stability.（5）The degradation mechanism for BPA of MIP-TiO₂/GR were studied.Results showed that electron hole pair was the fundamental causing catalytic reaction,and hydroxyl radicals were the main active substance.