Study On Preparation And Properties Of Indoor Formaldehyde Removal Materials

Formaldehyde?HCHO?is a ubiquitous indoor air pollutant that can cause various types of discomfort and illness after prolonged exposure.Therefore,it is of paramount importance to remove HCHO from indoor air.At present,there are many materials and products for removing formaldehyde.However,there are many shortcomings that cannot be ignored.For example,the most widely used titanium dioxide semiconductor material has problems such as low natural light utilization rate and inconvenient forthputting.In this thesis,formaldehyde was used as the research object,and the photocatalytic materials and adsorbent materials for removing formaldehyde were prepared.Then the properties and mechanism of the prepared materials were systematically studied.Finally,we compare the performance of two types of home-made materials with those on the market.The main research content of this thesis includes:A new method for the determination of formaldehyde degradation products was established.By connecting the catalytic reaction unit to the gas chromatograph,it is possible to directly test the degraded gas product.The TDX-01 packed column was selected for separation using a TCD detector with a detection limit of 1.05?g/L.Compared with the traditional spectrophotometer method,our way avoids the interference of external environmental components?such as HCHO,CO₂?.This approach directly determines the degradation product CO₂ and the change law,which is beneficial to study the process and mechanism of catalytic material degradation of formaldehyde.The layered bismuth copper oxysulfide?BiCuSO?nanomaterials were successfully prepared by hydrothermal method.Then AuBiCuSO photocatalytic materials were synthesized by doping gold,Au/BiCuSO and Ag/BiCuSO photocatalytic materials were synthesized by loading gold and silver by precipitation-reduction method.By introducing uniformly dispersed precious metal nanoparticles into the material,the electron mobility and the amount of active oxygen of the catalytic material are increased,thereby improving the catalytic activity.Scanning electron microscopy,X-ray diffraction,ultraviolet-visible diffuse reflectance spectroscopy,and X-ray photoelectron spectroscopy were performed on the physical as well as photophysical properties of BiCuSO and its modified materials.The results show that BiCuSO with the gold content of 0.9%,AuBiCuSO has the highest photocatalytic oxidation of removing formaldehyde,as high as 98%,at a synthesis temperature of 140?.The Au/BiCuSO and Ag/BiCuSO photocatalytic materials prepared by the reducing agent have the highest degradation rate of 98%at the loading of 1.0%and1.5%,respectively.Hydroxyapatite?HAP?was synthesized by hydrothermal method.The synthesized HAP was characterized by XRD and IR.As results shown that the synthesized HAP had excellent crystallinity and high purity.The Usnea/HAP composite adsorbent material was prepared through blending HAP with natural pine stalk by dipping method,immediately after the influence of contact time and initial concentration of formaldehyde on the adsorption effects were also discussed.Above all,adsorption kinetics and adsorption models for formaldehyde adsorption in air were studied.Additionally,the contact temperature of the Usnea/HAP composite material with formaldehyde gas reached the saturated adsorption amount after 90 min,which accorded with the pseudo first-order kinetics and the Freundlich isotherm adsorption model.The theoretical saturated adsorption of formaldehyde to the material was 546 ng/g by simulation.The formaldehyde scavenger products purchased on the market are compared with the self-made photocatalytic materials,TiO₂,g-C₃N₄ to remove formaldehyde.The self-made materials have better degradation effect than various sprays,TiO₂ and g-C₃N₄,and the degradation rates of self-made photocatalysts are 4.7 and 5.5 times that of TiO₂ and g-C₃N₄,respectively.The homemade Usnea/HAP composite material was compared with the commercially available Nas-carbaldehyde adsorption paper and the Nano-net aldehyde stone to remove the formaldehyde effect.The result shows that the effect of the Usnea/HAP composite on the adsorption of formaldehyde is similar to the two materials on the market.It shows that the material has broad application prospects for the treatment of toxic gases.