Surface oxidation modification is mainly to oxidize the functional groups on the surface of activated carbon materials by using appropriate oxidants at appropriate temperatures, so as to improve the content of oxygen-containing groups on the surface of carbon materials, enhance the surface hydrophilicity and polarity, and enhance the adsorption capacity of polar substances.
The number and types of oxygen-containing functional groups are different after treatment with different oxidants.Oxidation treatment also changed the void structure of activated carbon B1 ban1.
The commonly used modified oxidants mainly include HNO, HClO, HPO, H,SO4, HF, O and HO, etc.
Oxidant HNO;After the modified activated carbon was treated with proper amount of nitric acid, the mesopore increased, the ratio of carboxylic hydroxyl increased, the surface polarity of activated carbon increased, and the adsorption capacity of some solutes with certain polarity increased.However, excessive nitric acid modification treatment will increase the unstable groups on the surface of activated carbon and fail to achieve the predetermined effect 18-20].
After modified by HCIO with mild oxidation, the number of oxygen-containing groups on the surface of activated carbon increased, but the micropore structure and specific surface area did not change much.After ozonation treatment, the number of oxygen-containing acid functional groups on the surface of activated carbon and the surface acidity increased, and the adsorption rate and capacity of C** increased. P-Morwski et al. 2 used HNO to oxidize the carbon synthesized from phenols, and the adsorption performance of the treated activated carbon material to trihalomethane was greatly improved.Shan Xiaomei et al. 2 found that the surface area and pore volume of activated carbon decreasedafter high concentration of HNO treatment.However, the surface and pore volume of activated carbon increased after low concentration HNO treatment.(NH4) S0.Oxidation changes the micropore size distribution of coal-based carbon, but has little effect on the micropore size distribution of coconut-shell carbon.In addition, the number of carboxyl groups on the surface of activated carbon increased obviously after modification of HNO, (NH4)S;
The amount of phenolic hydroxyl group and lactone group on the surface of activated carbon increased significantly after OG modification.Tsutsumi after 2 ⒂ activated carbon materials such as activation, first under the condition of the air cooled to about 400 ℃, and then with a good contact with air oxidation treatment, can increase the alkali activated carbon material surface oxide hydroxyl groups on the surface of the the surface polarity and hydrophilic increased, can adsorption in aqueous solution polarity organic matter and inorganic matter.Generally speaking, activated carbon with very rich micropores can be successfully obtained by chemical activation followed by physical activation.It was found that after chemical activation with ZnCH and physical activation with carbon dioxide, walnut activated carbon could further open and expand pores.H The lignocellulosic activated carbon was activated by mixing H,PO and ICOZ to obtain super activated carbon with high specific surface areaThe chemical modification of the adsorption surface of activated carbon material is to improve the structure of the functional groups and surrounding atmosphere on the adsorption surface of activated carbon material by certain methods, so as to make it become the active point in the specific adsorption process, so as to control the hydrophilic or hydrophobic properties and the binding ability with metal or metal oxides.Surface chemical properties of activated carbon materials can be modified by oxidation modification, reduction modification, metal loading modification, acid base modification, heteroatom carrying and compound modification, graft polymerization, etc. Surface oxidation modification of activated carbonIn order to provide reference and theoretical basis for the preparation and selection of activated carbon for the adsorption of dioxins, this paper carried out a study on the combined technology of activated carbon injection and double bag dust collector, the characteristics of activated carbon adsorption for dioxins and the influencing factors of activated carbon adsorption for dioxins.The adsorption and desorption isotherms of 13 kinds of commercial activated carbon were determined by low temperature nitrogen adsorption method, and the physical structures of activated carbon were calculated according to BET, T-Plot, BJH and DFT theory, and the iodine value and methylene blue value of 4 kinds of activated carbon were detected.
The physical structure characteristics of activated carbon were analyzed in detail to prepare for the subsequent experiment.
Using small activated carbon fixed bed adsorption gas phase dioxin test bench, a typical activated carbon adsorption dioxin factors affecting the experimental study, discusses the types of dioxin adsorption activated carbon and activated carbon fixed bed adsorption gas phase characteristics of dioxins, and discusses the adsorption temperature and adsorption time of activated carbon adsorption of dioxins.The results showed that the specific surface area and micropore volume of activated carbon had weak correlation with the adsorption efficiency of dioxins.
The mesopore volume of activated carbon is an important factor to determine the adsorption capacity of dioxins. The surface area of the pore size between 2 nm and 20nm plays a key role in the adsorption of dioxins.The higher the adsorption temperature, the lower the adsorption efficiency of activated carbon.The longer the adsorption time, the lower the adsorption efficiency of activated carbon.There is no selective adsorption of gaseous dioxins in activated carbon fixed bed. | 
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