| Odor pollution is harmful to the environment and human health.Among them,the organic odor of mercaptans has the characteristics of low odor threshold and strong volatility.Excessive intake can cause symptoms such as nausea,vomiting and loss of olfactory,and can cause suffocation and death when severe.Adsorption method is a conventional method to deal with odor pollution,and it has the characteristics of fast,simple and effective.However,due to the large amount of contaminants attached to the saturated sorbent,improper disposal causes secondary pollution.The microwave ultraviolet regeneration process has the advantages of short regeneration time,high degree of mineralization,and is an efficient regeneration process.In this study,ethanethiol was used as the representative substance to study the effectiveness and mechanism of the activated carbon adsorption-microwave ultraviolet regeneration process.The adsorption efficiency of activated carbon under different conditions was investigated.The adsorption kinetics of activated carbon at different temperatures were investigated.The activated carbon with saturated adsorption was regenerated by microwave UV regeneration method.The regeneration efficiency was evaluated by considering the regeneration rate and the loss rate of activated carbon.The mineralization of ethanethiol was analyzed for its degradation mechanism.On the basis of experiments,preliminary design of the waste gas treatment process of calcium carbonate board factory was carried out,and economic and feasibility analysis was analyzed.Concluded as follow:Compared with coal activated carbon and shell activated carbon,there are oxygencontaining functional groups such as hydroxyl,carbonyl,and carboxyl groups on the surface of coconut shell activated carbon(10-20 mesh),with a maximum adsorption capacity of 315.58 mg/g.The Yoon-Nelson model fits the adsorption of ethanethiol onto activated carbon and the correlation coefficient is greater than 0.99.The effect of four factors on the adsorption efficiency of activated carbon was investigated.The optimal adsorption conditions were as follows: initial concentration of ethanethiol 17 mg/L,flow rate 1000 ml/min,humidity 80%,and temperature 15°C.The adsorption kinetics of activated carbon accords with the Bangham equation,and the adsorption isotherm conforms to the Freundlich adsorption isotherm model.The effects of microwave UV regeneration under different regeneration conditions on the regeneration of activated carbon were investigated.The optimal conditions were: regeneration time 150 s,air flow rate 200 ml/min,and microwave power 700 W.At this time,the regeneration rate is 101.4%,the loss rate is 4.12%.Compared with microwave regeneration alone,the microwave UV regeneration process has a better regeneration of activated charcoal.The degree of mineralization of ethanethiol increases with the extension of regeneration time,and after 10 minutes,the mineral velocity slows down significantly.Therefore,the microwave UV regeneration process has the potential to mineralize ethanethiol to SO2,CO2,H2 O simple substances.Combined with the actual odor emissions of mercaptans from the actual calcium carbonate board factory,the adsorption-microwave UV regeneration process was designed,which mainly includes: cooling system,adsorption system and microwave UV regeneration system.The main parameters of the process were calculated as: diameter of activated carbon adsorption tower 0.4m,height 0.26 m,amount of activated carbon 3.35 kg,bed pressure drop 177.47Pa;microwave regeneration power 60 KW,regeneration time 50 min,regeneration air flow rate 8.34m3/h.Taking into account three factors of energy consumption,loss rate of activated carbon and regeneration rate,the microwave UV regeneration process has a good economy. |
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