Adsorption And Photocatalytic Degradation Properties Of Highly Hydrophobic Molecular Sieve Supported Bi₂O₃-TiO₂ For Endocrine Disrupting Compounds

The endocrine disrupter problem in water environment has caused worldwide concern.Endocrine disrupting compounds（EDCs）are not easy to degrade,and possess the characterististics of the low concentration in water.Most of them can accumulate in body through the food chain and bioaccumulation,causing huge impact on the ecological balance and human health.Conventional water treatment methods: e.g.,coagulation,sedimentation,filtration and disinfection,do not effectively remove dibutyl phthalate（DBP）from treated water.Therefore,an efficient pollution control method of targeted adsorption combined photocatalytic oxidation was proposed.In our study,3,3,3-trifluoropropyltrimethoxysiane was used as a modifier for surface hydrophobic modification of mesoporous silica,which can lead to the highly thermal stability of adsorbent and the selective adsorption performance for EDCs such as DBP and nonylphenol（NP）with low concentration.Then coupled semiconductor Bi₂O₃-TiO₂ with visible light response was loaded on the hydrophobic mesporous silica to study the adsorption enrichment-photocatalytic degradation performance for endocrine disrupters.Mesitylene（TMB）was used as a pore-expanding agent and 3,3,3-trifluoropropyltrimethoxysiane was used as a modifier to prepare the highly hydrophobic mesoporous silica with different pore sizes.The results showed that the adsorption capacity of underreamed adsorbents for DBP were significantly higher than that of the adsorbent without expanding agent.When the molar ratio of TMB relative to SBA-15 was 0.75,the adsorption capacity can reach the maximum of 79.73 mg/L.The struction and surface properties of samples were characterized by N2 adsorption/desorption isotherms and pore-size distribution,FT-IR spectra and element analysis.It was found that the introduction of 3,3,3-trifluoropropyl can improve the hydrophobicity of the mesoporous silica,and after reaming,the larger pore size and specific surface area of the mesoporous silica can provide more grafting sites for the modifier,which is in favour of the load of organic functional groups and the diffusion of the pollutant molecules.Three kinds of fluorine-containing organic silane（triethoxyfluorosilane,trifluoropropyltrimethoxysiane and nonafluorohexyltrimethoxysiane）were grafted on the surface of SBA-15,representative,and the adsorption capacity of adsorbents were investigated.–F groups have no the characteristic of lipotropy,and the chain length of nonafluorohexyl groups is too long,which can result in the inefficient adsorption.Meanwhile,the adsorption effect of the adsorbents for three typical endocrine disrupting compounds DBP,NP and bisphenol A（BPA）were studied.It was shown that highly hydrophobic TFP-SBA-15 can reach the best adsorption performance,illustrating that the hydrophobicity and lipotropy of the adsorbent should match with the target pollutant.Bi₂O₃-TiO₂ was synthesized by the hydrothermal method,then it was supported on the hydrophobic modified molecular sieves to prepare the on-site adsorption-visible light degradation available photocatalyst.By the hydrophobic modification and combination with visible lighte responsive catalyst,the activity of the composite photocatalyst can reach 96.8 % under the visible light irradiation.The physicochemical properties of the catalysts were characterized to investigate the relation between the structure of the materials and their photocatalytic performance.It was found that the high-efficiency removal for DBP was the result of synergistic effect of adsorption and photocatalytic degradation.