Research On Adsorption Property Of Polypropylene Function Material And Its Gas Purification Application

Indoor air pollution is the 3rd generation pollution problem following the coal-smoke pollution and the photo-chemical pollution. Along with the air pollution and the introduction of many architectural decoration materials, household appliances, etc. into human residence,many indoor pollutants with more complex composition are caused thereby and gradually threaten human health, thus making the indoor air purification become a problem which should be urgently solved by people. Adsorption is a classical indoor air purification technology and can be collaboratively applied with other purification technologies. Therefore,the scholars in this field mainly focus on researching and selecting more efficient absorbent materials for indoor air purification.This paper aims at studying the adsorption property of a polypropylene function material for the most common pollutant---- formaldehyde in the indoor air pollution and discussing the application thereof in the purification of the indoor polluted air. Firstly, Boehm titration,thermo gravimetric analysis, infrared analysis, scanning electron microscope, etc. are adopted to characterize H type and Na type polypropylene function materials and the activated carbon.Then, the dynamic equilibrium adsorption system and the static adsorption system are adopted in the laboratory to discuss and disclose the adsorption characteristics of the polypropylene function material for formaldehyde. Finally, the polypropylene function material is combined with the filtration technology for the application in the air purifier.Moreover, the indoor environment polluted by formaldehyde and PM_2.5 pollutant is simulated in the environment simulating chamber in order to evaluate the comprehensive purification effect of the purifier. The research results are as follows:Firstly, the difference of the surface characteristics of the polypropylene function material and the activated carbon is analyzed. Specifically, the polypropylene function material and the activated carbon both have many surface micro-pores for transport and capillary condensation, wherein the quantity of functional groups of the polypropylene function material is obviously higher than that of the activated carbon, thus favorable for improving the adsorption property. However, compared with the activated carbon, the polypropylene function material, especially H type function material, has poorer thermal stability.Secondly, the adsorption properties of the polypropylene function material and theactivated carbon for formaldehyde under different temperature conditions are disclosed in this paper. The result shows: in case of low formaldehyde concentration, the activated carbon and Na type function material have better effect; in case of low temperature and high concentration, Na type function material has better effect; in case of high temperature and high concentration, Na type function material and the activated carbon are relatively practical.The polypropylene function material and the activated carbon both release heat during the formaldehyde adsorption process thereof, and the adsorption quantity is reduced under high temperature. Meanwhile, L-F equation and Toth equation have better fitting degree with Na type function material, Langmuir equation and L-F equation have better fitting degree with the adsorption equilibrium isotherm of the activated carbon, and Na type function material has rapid adsorption rate and is difficult to reach saturation under high concentration.Thirdly, a method of applying Na type function material and the activated carbon for the adsorption purification net is provided in this paper. Due to different densities and particle diameters, when the two absorbents are directly loaded to form thick single-layer adsorption purification net, the polypropylene function material with small particle diameter is filled among the activated carbon particles to cause large wind age resistance; after running for a certain period, along with the wind disturbance, the polypropylene function material will precipitate and compact at the lower layer of the cellular pores, thus causing the non-uniform mixing of the two absorbents; as a result, air only passes through the activated carbon and has a very small contact surface with the polypropylene function material. If two thin adsorption nets are adopted, then the adsorption framework becomes too soft and the purifier will have air leakage phenomenon. Therefore, the double-layer structure is adopted to integrate Na type function material and the activated carbon into the adsorption purification net for solving above problems.Finally, the scheme for applying the absorbents in the air purifier is discussed in this paper and the indoor air purification effects of various schemes are also evaluated.Specifically, Scheme II---- activated carbon adsorption net has better PM_2.5 purification effect,wherein CADR（Clean Air Delivery Rate） is 94.42m3/h, the purification efficiency is 31.47%,and the removal rate can reach 98.55% in 30 min. Scheme III---- the double-layer adsorption net based on Na type function material and activated carbon has better formaldehyde purification effect, wherein the formaldehyde removal rate is approximate to 80% in 2h and the purification efficiency is 2.69%, and this scheme can not only ensure the highformaldehyde adsorption efficiency of the activated carbon and Na type function material respectively under low concentration and high concentration, but also ensure the rapid adsorption rate of Na type function material, and PM_2.5 removal rate of this scheme is approximate to that of Scheme I in 30 min, namely above 90%.