Study On Preparation Of TiO₂/Al₂O₃/Fe₃O₄ Photocatalytic Magnetic Fluid And Its Photocatalytic Activity And Magnetic Recovery

Nano-TiO₂ photocatalytic oxidation degradation of water pollutants have no selectivity and no secondary pollution of advantages,in recent years becoming a removal of water organic pollutants have great prospects for the application of green governance.In order to solve the problem that the nano-TiO₂ particles in the suspended state are small in size,the recovery and utilization of difficulty and the running cost with increased,the magnetic photocatalyst research is dedicated to solving the problem.At present,most scholars choose titanium alkoxide as raw material,Al₂O₃/Fe₃O₄ carrier as magnetic core.Titanium salt was hydrolyzed to obtain Ti（OH）₄ sol,which was prepared by drying and grinding to prepare the magnetic TiO₂ photocatalyst with different properties.The process of prepared photocatalyst has obvious agglomeration of particles and cause the drying powder off.Under the condition of no drying and grinding magnetic TiO₂ photocatalytic magnetic fluid can be prepared with good coating and magnetic recovery.However,due to the rapid hydrolysis of butyl titanate,the TiO₂ particles are difficult to stabilize on the surface of Al₂O₃ / Fe3O4 carrier,So the key point of this study is how to prepare the magnetic TiO₂ photocatalyst with good coating and magnetic recovery under the condition of no drying and grinding.To solve the problem,the method of this paper taken tetrabutyl titanate as titanium source and Al₂O₃/Fe₃O₄ carrier as magnetic core,by different preparation conditions obtained Al₂O₃/Fe₃O₄ carrier and studied its on the catalytic performance of loaded-TiO₂ photocatalytic magnetic fluid.The effect of Al₂O₃/Fe₃O₄ carrier on the catalytic performance of by hydrothermal method prepared TiO₂ photocatalytic magnetic fluid was studied.TiO₂/Al₂O₃/Fe₃O₄ multifunctional photocatalytic magnetic fluid with composite structure was analyzed.The factors of ingredients ratio,pH value,acetic acid（HAc）,acetylacetone（AcAc）and triethanolamine（TEOA）had diffirent impact on the synthesis of TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid.Different hydrolysis agents could inhibit the hydrolysis and polycondensation rate of butyl titanate and reduced the hydrolysis rate.It was beneficial to produce magnetic-loaded TiO₂ photocatalytic magnetic fluid with better coating performance.The hydrothermal reaction prepared the magnetic TiO₂ photocatalytic magnetic fluid with excellent photocatalytic performance and easied to put into use.The prepared magnetic-supported photocatalysts were characterized by X-ray diffraction（XRD）,Fourier transform infrared spectrophotometer（FT-IR）,transmission electron microscopy（TEM）andvibrating sample magnetometer（VSM）.The initial concentration of 25mg/L phenol solution as a simulated pollutant,its photocatalytic degradation to investigate its catalytic activity.The main findings were summarized as follows:（1）TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid was prepared by low temperature hydrothermal method.The investigation of reaction conditions of Al₂O₃/Fe₃O₄ carrier have a certain impact on the physical and chemical properties and photocatalytic activity of magnetic TiO₂ photocatalytic magnetic fluid.The experimental results show that the preparation conditions of Al₂O₃/Fe₃O₄ carrier with high photocatalytic activity of magnetic TiO₂ photocatalytic magnetic fluid Al₂O₃: Fe3O4 = 4: 1,pH = 7,calcination temperature =400 ℃,holding time = 60 min,while adding 20 ml 0.1mol/L sodium dodecyl benzene sulfonate,the magnetic TiO₂ photocatalytic magnetic fluid degradation rate of phenol reached81.2%.（2）Acetylacetone（AcAc）,triethanolamine（TEOA）and glacial acetic acid（HAC）as complexing agent,ethanol as a dispersant,nitric acid as solvent while acidic conditions can slow the hydrolysis rate of butyl titanate,Al₂O₃/Fe₃O₄ carrier as magnetic core,nano-TiO₂ particles were immobilized on the Al₂O₃/Fe₃O₄ surface by sol-gel method,after hydrothermal reaction,the shell / shell / core structure of the magnetic TiO₂ photocatalytic magnetic fluid was prepared.The effects of the reaction conditions during the preparation of TiO₂/Al₂O₃/Fe₃O₄ on the catalytic performance of magnetic TiO₂ photocatalytic magnetic fluid was investigated.The results show that the photocatalytic activity of TiO₂ nanoparticles prepared by TiO₂: Al₂O₃:Fe3O4 = 60: 4: 1,initial pH = 9 and HAC = 8ml is 81.2%,and the coating performance of nano-TiO₂ particles on the surface of magnetite Al₂O₃/Fe₃O₄ is stable.Under the action of external magnetic field,the catalyst can be separated from the liquid phase rapidly,and the recovery rate is 61.5%.（3）Titanium titanate as a titanium source is very easily hydrolyzed to produce white flocculent precipitate,in the form of large particles alone in the solution.Based on the resolve resolution of Al₂O₃/Fe₃O₄ carrier and TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid of the experiment,the agglomeration and dispersion properties of the Al₂O₃/Fe₃O₄ carrier were investigated according to the surface force of titanium supported particles.TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid was prepared by loading TiO₂ on the its surface.So that it has both high catalytic efficiency at the same time,but also to overcome the cumbersome preparation process and the high cost of shortcomings.（4）Butyl titanate was easily hydrolyzed with water,when 8ml HAc was added as the hydrolysis of butyl titanate to minimize the formation rate of TiO₂,so that TiO₂ could be immobilized on the surface of Al₂O₃/Fe₃O₄ carrier.The best effect of magnetic TiO₂ photocatalytic magnetic fluid was obtained.（5）In order to make the solution kept sol-gel state,when TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid was prepared,using ammonia adjusted the pH value of the system to neutralize the nitric acid in the solution,Which contributed to the formation of the magnetic fluid state of the photocatalyst.At the same time,the magnetic core Al₂O₃/Fe₃O₄ carrier was protected from excessive strength acid corrosion,which led to the dissolution of the magnetic core and not conductived to the preparation of TiO₂/Al₂O₃/Fe₃O₄ photocatalytic magnetic fluid.