Synthesis Of Pt-TiO₂@BC And Its Photocatalytic Degradation And Adsorption Properties For Dye

As a photocatalyst,titanium dioxide（Ti O₂）is often used in solar cells,water pollution treatment,coatings and other fields.However,the development of Ti O₂in the field of photocatalytic degradation is limited by its low utilization rate of visible light and high recombination rate of photogenerated charge carriers.Therefore,the exploration of improving the photocatalytic performance of Ti O₂is a hot research trend in recent years.In this paper,bio-based carriers or precious metal nanoclusters are introduced into the preparation process of Ti O₂by doping and other means to endow it with multifunctionality.The morphology,structure and properties of the composite materials are characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）and other means.The optimal synthesis conditions and photocatalytic degradation mechanism were explored to evaluate the catalytic performance improvement effect of precious metal nanoclusters on Ti O₂and to provide a feasible scheme for the practical application of Ti O₂in the field of textile printing and dyeing wastewater treatment.The main contents of this paper are as follows:1.The bio-based bacterial cellulose（BC）is used as the carrier to support Ti O₂,and the Ti O₂@BC composite material is prepared by adjusting the amount of catalyst introduced and the way of film making,so as to solve the problems of difficult recovery and secondary pollution caused by Ti O₂in the practical application process,and provide a feasible scheme for its practical production and application.The results showed that the composite of Ti O₂@BC,BC and Ti O₂prepared by freeze-drying did not change the 3D network structure of BC,while retaining the internal pores of BC,and when the amount of Ti O₂introduced was 50%,the catalytic performance of the membrane material was the best,and the pollutant treatment ability was the strongest.2.Put forward an improvement plan to solve the problem of poor photocatalytic performance of Ti O₂.Precious metal nanoclusters（Pt NCs）were introduced into Ti O₂to form Pt-Ti O₂composites.The effects of the introduction amount of precious metal nanoclusters on catalytic performance,Ti O₂crystal form,band gap width and other factors were systematically studied.The optimal doping conditions of precious metal nanoclusters were determined,and their effects on the improvement of catalytic performance of Ti O₂were evaluated.To construct a mechanism for co-improving the photocatalytic degradation performance of Ti O₂by precious metal nanoclusters.According to XRD,DRS and XPS detection and analysis,the introduction of Pt will reduce the band gap width,broaden the optical response range of Ti O₂,and increase the absorption of the material in the visible light region.According to the degradation experimental results,when the amount of Pt NCs is 3.7%,the catalytic activity of the sample is the best,and the degradation rate exceeds 99%in 270 min at the beginning of the experiment（90 min after the light is turned on）,far exceeding the degradation effect of pure Ti O₂.3.According to the experimental results,the ternary BC as the carrier,precious metal nanocluster doped with Ti O₂composite material（Pt-Ti O₂@BC）is designed;The existence of internal pores of bacterial cellulose prevents the agglomeration of Pt NCs,which is conducive to the mass transfer process in adsorption and degradation.Moreover,the existence of bacterial cellulose fiber provides a substrate for titanium dioxide to adhere to,and solves the problem of titanium dioxide recovery.4.In addition to the photocatalytic degradation performance,Pt-Ti O₂@BC composite material shows the characteristics of differential adsorption of negative and cationic dyes;Through adsorption kinetics,adsorption thermodynamics,adsorption isotherm and other studies to explore the adsorption properties of materials.In view of the cationic dye wastewater in actual production,the adsorption performance of the composite material RCTMA@BC loaded with recylized pyromellitic acid on BC was explored,and compared with Pt-Ti O₂@BC.The experimental results show that Pt-Ti O₂@BC has a good adsorption capacity for anionic dyes,and the adsorption of Pt-Ti O₂@BC for acid bright red conforms to the quasi-second-order kinetic model.The maximum value of qe calculated is 162.8665 mg/g,and the isotherm model conforms to the Langmuir model,R²=0.9964.The results of thermodynamic experiments show that when T=298 K,△G=-0.7595 is negative,indicating that the adsorption process is spontaneous at this temperature,and△H=-28.14574 is negative,indicating that the adsorption process is unfavorable at higher temperatures.RCTMA@BC has excellent adsorption capacity for cationic dyes.The adsorption isotherm conforms to Langmuir model,R²=0.9870,and the maximum adsorption capacity of methylene blue is 1162.12mg/g.The adsorption kinetics fitting shows that the adsorption of RCTMA@BC to methylene blue conforms to the quasi-second-order kinetic equation and belongs to chemisorption,while the adsorption efficiency of the anionic dye acid bright red is poor.In summary,this paper mainly prepared anatase type titanium dioxide by low-temperature gel-sol method,and loaded it on bacterial cellulose.In order to expand the photoresponse region of titanium dioxide,it was modified by introducing precious metal nanoclusters,and its practical application and related mechanism of adsorption and photocatalytic degradation of organic dyes were studied by corresponding means.