Study On Tea-based Adsorption Material

Tea is classified as a porous solid not only does it have the appearance of this structure, but also it is richin inorganic compounds and organic compounds. There are more than15kinds of inorganic compounds andmore than450kinds of organic compounds extracted and appraised. Among these the alkaloids, teapolyphenols and amino acids are the main active ingredients, which wipe out VOCs such as formaldehyde,ammonia, benzene and so on.Activated carbon is a material which has developed a pore structure, large specific surface area, surfacefunctional groups and special adsorption organic VOCs capacity. Compared with other adsorbents, it has goodchemical stability, mechanical strength and alkali resistance, acid resistance and heat-resistant performancecharacteristics. Because of its absorption, desorption speed and renewable advantages; it has the ability tobecome an extremely wide range of absorbing material.In this thesis, oolong tea stalks which was an activated carbon, was used as raw materials. The main aimgasses were formaldehyde, ammonia and benzene. We prepared for high adsorption performance with afunctional adsorption material. By using the response surface method, orthogonal design method and adsorbent(citric acid, ferrous sulfate, copper sulfate, Sulfonated cobalt phthalocyanine) individually.According to the law of Response Surface Methodology (RSM), Box-Behnken Design (BBD) wasemployed to establish the mathematical models of the experiment and to discuss the effect of different factorsto the adsorption value. Based on RSM, we optimized the best technologies for the experiment.To begin with the functional formaldehyde adsorption material prepared by the BBD process, the valuesfor the formaldehyde adsorption predicted by the developed model are in good agreement with the measuredones. The correlation coefficient (R2) of the regression models and the adjusted R2，were respectively0.7463and0.4926．The optimal conditions are shown as follows: the content of active carbon was27.4%, the contentof citric acid was4.4%, the content of Ferrous Sulfate was4.6%, the content of Sulfonated cobaltphthalocyanine was1%and the content of tea stalk was61.6%. Under the optimum, the formaldehydeadsorption value would reach279.32mg/g the highest value in our investigation.For the functional ammonia adsorption material prepared by the BBD process, the values of the ammoniaadsorption predicted by the developed model were in good agreement with the measured ones. The correlationcoefficient (R2) of the regression models and the adjusted R2，were respectively about0.7242and0.4485．Theoptimal conditions are shown as follow: the content of active carbon was39.7%, the content of citric acid was4.5%, the content of Ferrous Sulfate was7.7%, the content of Copper Sulfate was1.2%and the content of tea stalk was46.9%. Under the optimum conditions, the ammonia adsorption value would reach379.32mg/g thehighest value in our investigation.Thirdly, the research used an orthogonal test design to compare the absorption of benzene with differentadditives and in different proportions. The results showed that the adsorption capacity of the CompositionMaterials consisted of80%Active Carbon,4%for Ferrous Sulfate and0%for Citric Acid which performedthe best, the benzene adsorption value would reach315mg/g.For the purpose of offering the theory of the preparation of high-performance functional adsorptionmaterial, the structure of functional adsorption material was deeply characterized by advanced technologies.Scanning Electron Microscope, Fourier Infrared Spectrograph, Surface area and Pore Analyzer and so on. Theresults show that functional adsorption material samples with many developed pore structure, and the pore sizedistribution is wide. The hole shape including circle, fracture type and irregular type. The samples are rich ofhydroxyl, carbonyl, lactone and other functional groups. Adding citric acid and other additives cansignificantly increase the number of functional groups. The adsorption isotherms of each sample are type IV,and the size of mesoporous is2~20nm.