Preparation And Properties Of Noble Metal/TiO₂/Cotton Fiber And SiO₂/C Sphere Environmental Purification Materials

With the rapid development of the social economy,the people's living standards have been improved greatly,and environmental problems such as indoor air and water pollution have been increasingly valued by everyone.Formaldehyde is one of the main pollutants in indoor air,and dye waste-water is one of the main sources of pollution in water.In order to improve indoor air quality and purify water bodies,it is of great theoretical and practical value to develop high-efficiency environmental purification materials.Room temperature catalytic oxidation is the most potential method for formaldehyde removal.However,most of the catalysts are powders,and have high air resistance,which are not suitable for practical application.The adsorption method is one of the main methods for removing dyes in water,but the existing adsorbents have problems such as low specific surface area and small adsorption capacity.In response to these problems,this paper has done the following work:?1?In order to reduce the air resistance of the catalytic material,using cotton as a carrier,and the TiO₂ sol is prepared by tetrabutyl titanate as a precursor.The surface of cotton fiber was modified by impregnation method.Then,Pt/TiO₂/cotton fiber composite catalyst?PTC?was prepared by the combination of precipitation and NaBH₄ with chloroplatinic acid as precursor,and it is used for catalytic oxidation at room temperature to remove formaldehyde.The air resistance of the prepared PTC composite catalytic material was studied;The effect of TiO₂ coating on the catalytic performance of cotton fiber before and after modification was compared;The effect of Pt loading on the catalytic performance was investigated;The mechanism of its catalytic oxidation reaction was studied.?2?In order to reduce the air resistance of the catalytic material and further reduce the cost,using cotton as a carrier,and the TiO₂ sol is prepared by tetrabutyl titanate as a precursor.The surface of cotton fiber was modified by impregnation method.Then,Pd/TiO₂/cotton fiber composite catalyst?DTC?was prepared by the combination of precipitation and NaBH₄ with palladium nitrate as precursor,and it is used for catalytic oxidation at room temperature to remove formaldehyde.The air resistance of the prepared DTC composite catalytic material was studied;The effect of TiO₂ coating on the catalytic performance of cotton fiber before and after modification was compared;The effect of Pd loading on the catalytic performance was investigated;The mechanism of catalytic oxidation of formaldehyde at room temperature by DTC composite catalytic materials was studied.?3?Using resorcinol,formaldehyde and tetraethyl orthosilicate as precursors,the hierarchical porous SiO₂/C hollow microspheres?HPSCHMs?were synthesized by soft template method,hydrothermal method and NaOH etching treatment.The adsorption performance of HPSCHMs on Congo red?CR?was discussed.The adsorption kinetics,isotherms and thermodynamics were analyzed and analyzed.The mechanism of HPSCHMs adsorption of Congo red was studied.The main results of the paper are as follows:?1?The air resistance of the PTC composite catalyst is much lower than that of the powder sample.It can decompose formaldehyde to CO2 and H2O at room temperature,and the optimum loading of Pt is 0.75wt%,and shows good catalytic stability.The TiO₂coating in the composite catalyst not only promotes the catalytic activity but also improves the stability of the catalyst.Formate,carbon monoxide and methylenedioxy?DOM?are the main intermediate species,and the mechanism of HCHO catalytic oxidation is proposed.?2?The DTC composite catalyst also has a resistance lower than that of the powder sample,and its catalytic activity increases with the increase of Pd content in the range of0.25¹.0wt%,and shows good catalytic stability.The TiO₂ coating in the catalyst plays an important role in achieving high catalytic activity and good stability.Formate,carbon monoxide and methylenedioxy?DOM?are the main intermediate species and the corresponding catalytic mechanism has been proposed.?3?HPSCHMs has a hierarchical porous hollow microsphere structure with a diameter of about 100 to 200 nm,and its surface area is up to 1127 m²?g^-1.It has significant adsorption properties for CR with a maximum adsorption capacity of 2512mg?g^-1.Under the same conditions,it showed a faster adsorption rate and a higher adsorption capacity than commercial activated carbon?AC?and?-Al2O3 samples.The adsorption kinetics,isotherms and thermodynamic studies show that the adsorption kinetics of CR on HPSCHMs samples accords with the pseudo-secondary model.The adsorption isotherm is in accordance with the Freundlich adsorption model,and the adsorption activation energy is about 7.72 kJ?mol^-1,which belongs to physical adsorption.Due to theirs low gas resistance,light weight,flexible properties and good catalytic efficiency,t as well as the wide source and low cost of carrier cotton raw materials.Therefore,PTC and DTC have broad application prospects in the field of air purification.HPSCHMs materials have great application potential in dye waste-water treatment due to their large adsorption capacity.