Study On The Polyester Nonwovens Supported N-doped Nano-TiO₂ Compositing Material And Degradation Of Formaldehyde

Since the 21st century,more and more people chosen cars as their means of travel,and the time spent in cars had become longer and longer.However,parts and interior materials used in cars emitted toxic and harmful volatile organic substances(VOCs),making cars become likely a killer that endangers our lives.The problems of air quality in cars couldnot be ignored.Therefore,it is greatly significant to find suitable materials for the adsorption and degradation of VOCs in vehicles.This paper discussed a new type of adsorption and degradation material-N/TiO₂ composite material,for achieving the purpose of reducing the content of formaldehyde in the air and textiles from the car.N-doped anatase TiO₂ photocatalysts were prepared by a conventional sol-gel method.Tetrabutyl titanate and urea were used as precursor and nitrogen source,acetic acid was used as carbon source which can inhibit the hydrolysis of titanium butoxide(TBOT).The X-ray photoelectron spectroscopy(XPS)result shown that the bandgap of TiO₂ was narrowed owning to the doping of N and carboxylate ligands,thus significantly enhancing the photocatalytic activities of TiO₂ for degrading liquid formaldehyde.In addition,the experimental conditions were optimized by adjusting the calcination temperature and the nitrogen-titanium input ratio.The result shown that the N/TiO₂ catalyst exhibit superb photocatalytic ability with the calcination temperature is 400?,and the ratio of nitrogen to titanium is 1:2,respectively.The degradation efficiency of formaldehyde can reach 71.50%after irradiation for 5 hours.The photocatalytic performance is significantly improved compared with pure TiO₂.It provides a route for the development of an efficient photocatalytic material.The alkali reduction method was used to pretreat polyester nonwoven fabric(PET)from car seats.The non-woven fabric was treated with sodium hydroxide.The optimal process parameters were obtained through orthogonal experiments.The result was 10 g/L Na OH solution with a bath ratio of 1:30,configured in a 80?water bath,and the treatment condition of PET immersion time was 60 min,which was more conducive to the subsequent preparation process.Due to the effect of caustic soda etching on the treated PET,there were many grooves and pores on the surface,and the moisture absorption performance was improved,which was conducive to the adsorption of small molecules and tiny impurities.Using sodium hexametaphosphate(SHMP)as the dispersant,the N/TiO₂ dispersion was prepared by magnetic stirring-ultrasonic dispersion,and the average particle size was compared through orthogonal experiments to obtain the optimal level combination.The result was:the mass ratio of N/TiO₂ and SHMP was 1:0.1,stirring time was 30 min,ultrasonic time was 20 min.The N/TiO₂ supported material was prepared by the dipping-two-dipping two-rolling-drying method.The morphological characteristics of the N/TiO₂ supported materials were observed by scanning electron microscope(SEM)and transmission microscope(TEM),and the results showed that nano-N/TiO₂ was successfully loaded on the surface of PET.The N/TiO₂ supported material was tested for the content of formaldehyde by the water extraction method,and tested systematically the effect of different influencing factors on the photocatalytic degradation activity.The test method was making materials immerse in 10 ppm formaldehyde solution,and then dryed for 24 hours,used a xenon lamp to conduct a photocatalysis experiment.Orthogonal experiments were used to analyze the effects of humidity,light intensity,light time and photocatalyst loading on the photocatalytic efficiency of N/TiO₂ supported material.Studies shown that the order of the factors affecting was the content of N/TiO₂ nanomaterial loading>humidity>xenon lamp illumination time>xenon lamp power.A conical flask was used as a closed environment to conduct experiments for testing the adsorption and degradation properties of the materials.In the conical flask,formaldehyde gas is generated by heating,and three different materials:pure PET,alkali reduction PET,and N/TiO₂ supported material were used to adsorb and photocatalytic degradate formaldehyde.The study results shown that the N/TiO₂ supported material had obvious adsorption and degradation effects on formaldehyde.The photocatalytic degradation efficiency reached69.50%within 80min.Finally,the synergistic mechanism of N/TiO₂ supported material on the adsorption and photocatalytic degradation of formaldehyde was systematically analyzed.