Preparation and photocatalytic properties of N-TiO2/polypropylene melt-blown nonwovens
Objective Titanium dioxide(TiO2)has non-toxicity,low cost,and high photocatalytic activity.However,the photocatalytic ability of TiO2 itself cannot reach the application level,and the powdered TiO2 is difficult to recycle and reuse.Thus,it is difficult for TiO2 to be practically applied in industrial fields.Polypropylene(PP)melt-blown nonwoven material with good chemical stability,low price,and simple manufacturing process has been widely used in air filtration,medical protection,and other fields.However,its single function limits its application.This research aims to improve photocatalytic ability and to tackle the recycling of TiO2 by doping N with TiO2 and then loading N-TiO2 nanoparticles on the surface of PP melt-blown nonwovens.Method N-TiO2 photocatalyst was first prepared by sol-gel method,and the optimal doping amount of N was determined by studying the surface morphology,microstructure,chemical structure,and photocatalytic performance of N-TiO2.The N-TiO2 photocatalyst with the best performance was loaded on the surface of PP melt-blown nonwovens by ultrasonic impregnation method.The surface morphology,chemical composition and structure,and photocatalytic properties of N-TiO2/PP composite melt-blown nonwovens with different N-TiO2 loading concentrations were studied.The photocatalytic mechanism of N-TiO2/PP composite melt-blown materials for organic dyestuff was verified and analyzed by free radical capture experiments.Results The particle size of N-TiO2 reached about 10 nm.N-TiO2 with N doping amount of 1%was found to have the best photocatalytic performance for MB.After loading the optimal N-TiO2 on the surface of PP melt-blown nonwovens,N-TiO2 were found uniformly wrapped on the surface of PP fibers.The agglomeration of N-TiO2 on the surface of PP fibers occurs when the loading amount of N-TiO2 exceeds 30 mg.Compared with PP melt-blown materials,the water contact angle of N-TiO2/PP composite melt-blown materials was significantly reduced,and the thermal stability was also improved.When the N-TiO2 loading amount is 30 mg,the photocatalytic degradation rate of N-TiO2/PP composite melt-blown material for MB reached 98%under the conditions of 30 min dark adsorption and 90 min photocatalysis.After trapping superoxide radicals(·O-2)and hydroxyl radicals(·OH),the photocatalytic MB degradation efficiency of N-TiO2 with 1%N doping were decreased by 22%and 23%,respectively.After being first used for the MB photocatalytic degradation,the crystalline structure and morphology of N-TiO2/PP composite melt-blown nonwovens remained the same.After the fourth MB photocatalytic degradation,the photocatalytic degradation efficiency of the composite melt-blown material for MB was about 58%.Conclusion Low N doping amount can effectively improve the photocatalytic performance of TiO2.N-TiO2/PP composite melt-blown material has proved to effectively degrade methylene blue dye.The composite melt-blown material has good stability and is recyclable.The research provides reference for expanding the application of PP melt-blown materials in the water treatment industry.
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