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Alkali Copper Modified Activated Carbon And Its Adsorption Effect On Toluene

Posted on:2022-09-09Degree:MasterType:Thesis
Country:ChinaCandidate:Z G HanFull Text:PDF
GTID:2491306338972259Subject:Environmental Science and Engineering
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With the rapid development of industry,the emission of volatile organic compounds(VOCs),and the pollution of VOCs in soils near cities and industrial areas are increasing.VOCs Pollution in soil has the characteristics of concealment,biological toxicity and bioaccumulation,which pose a potential threat to the ecological environment and human health.Activated carbon has abundant micro pores and great specific surface area,which is widely used in the adsorption treatment of organic waste gas.However,when activated carbon is used to adsorb soil gas VOCs,there is the problem of low adsorption capacity for non-polar substances such as toluene.Therefore,it is of great significance to find ways to enhance the adsorption effect of activated carbon on non-polar substances for the treatment of soil VOCs Pollution.Beaded Active Carbon(BAC)were modified by alkali treatment combined with metal loading.Alkali modification can reduce the number of acidic functional groups on the surface of activated carbon,and metal groups on the surface of activated carbon have a certain binding effect with VOCs.The physical and chemical properties of BAC before and after alkali combined with metal modification were analyzed,and the change of adsorption performance of BAC for toluene before and after modification was studied.SEM,BET,FT-IR and Boehm titration were used to characterize and analyze the BAC before and after alkali treatment combined with metal loading modification.The adsorption performance of modified BAC for toluene under different adsorption conditions was studied,and the regeneration effect of saturated activated carbon under different ultrasonic conditions was compared.The following conclusions were drawn:(1)After combined modification,the surface of BAC became rough,the irregular pores increased,the BET specific surface area,micropore volume and micropore specific surface area decreased,the average pore size remained unchanged,and the surface was loaded with copper.The combined modification has a strong targeting effect on carboxyl group.(2)The optimum modification conditions are as follows:when the concentration of sodium hydroxide solution is 8 mol·L-1 and the mass fraction of copper acetate solution is 0.5%,the modification effect is better.At this time,the maximum saturated adsorption capacity is 431.50 mg·g-1,which is 147.65 mg·g-1 higher than that before modification,the breakthrough time is 24 min longer and the equilibrium time is 61 min longer.The quantitative relationship of adsorption was consistent with the Yoon-Nelson kinetic model.The adsorption performance of modified BAC was affected by its pore structure and surface functional groups,and was significantly affected by surface functional groups and supported metal groups.The binding of copper and toluene on BAC surface was the main adsorption process.The saturated adsorption capacity of toluene was negatively correlated with the content of carboxyl and phenolic hydroxyl groups,but not with the content of lactone group.(3)The higher the temperature,the worse the adsorption performance of modified and unmodified BAC for toluene.The D-R model is more accurate at 25,35,45 and 65℃.The higher the concentration of toluene,the better the adsorption effect of modified BAC.The BAC modified by lower concentration of alkali is more easily affected by the concentration of toluene.Freundlich adsorption model can simulate the adsorption of different concentrations of toluene before and after BAC modification.(4)210 min is the best time for ultrasonic desorption regeneration,and the regeneration effect is proportional to the ultrasonic power.
Keywords/Search Tags:Beaded Activated Carbon, Joint modification, Targeted modification, Surface functional group, Toluene
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