Study On The Preparation And Modification Of Biochar For VOCs Adsorption Properties

At this stage,the industrialization and urbanization in our country has developed rapidly but the energy structure is relatively single,industrial development and residents’ life is bound to produce a large amount of VOCs emissions,VOCs pollution is serious so it is imperative to explore VOCs pollution prevention method.Among them,the method of adsorbing VOCs by activated carbon is one of the promising development directions due to the advantages of easy materials,low processing cost and good adsorption.However,the conventional methods for the preparation of activated carbon are smaller in surface area,adsorption selectivity,and uneven pore size distribution,etc.,and it need to be further modified to meet the needs of industry and life.Based on the type for raw material preparation of biochar,Boehm titration method,the specific surface area analysis,dynamic adsorption test method has been used to explore and optimize the preparation conditions and the modification methods of this kind of new biological carbon materials.The adsorption effect of modified biochar on benzene with benzene vapor is tested.The results are as follows:(1)The preparation of biochar was optimized:the biochar preparation process was designed,and the influence of the temperature on the chemical properties of biochar was discussed.The experiment showed that when the firing temperature was 800 ℃,the amount of oxygen-containing functional group on the surface of biochar decreased to 0.147mmol/g,and the surface area increased to 489.123m2/g,which was the best effect.(2)The alkalinization modification and alkaline condition of biochar were explored:the preparation of biochar was modified,and the effect of alkali concentration on the chemical properties of biochar was discussed.Experiments show that the alkalization process of sodium hydroxide can effectively improve the specific surface area of biochar and reduce the polar ability of biochar.When the alkalization concentration reached 10%,the alkalization effect was the best.The amount of oxygen-containing functional groups on the surface of biochar decreased to 0.134mmol/g,and the surface area increased to 519.137m2g.(3)The amount of load modified styrene biochar exploration:to load modification of complete alkaline biochar,the dynamic adsorption experiments show that the load of polystyrene biochar,can effectively improve the modification effect of the adsorption of benzene vapour biochar.The optimum concentration range of styrene was 0.25-0.5g in the experiment of biochar loading.(4)The surface chemical properties of modified biochar were characterized as follows:compared with the original biochar,the modified biochar was 24.56%higher than the surface area.The mean of initial adsorption efficiency increased by nearly 25%;The mean of saturated adsorption increased by nearly 19.7%.The area of mesoporous pores in the range of 0-25nm is improved.