Study On Adsorption Of Activated Carbon For Butyl Acetate And Trimethylamine Exhaust Gas

Butyl acetate is commonly used as organic solvent in industry.And trimethylamine is an important raw material for preparation of Tetramethylammonium hydroxide.Both of them are volatile.With the increasingly strict environmental protection requirements at home and abroad,the treatment of them is put on the agenda.Six kinds of active carbon were analyzed and characterized by SEM,N2 low temperature physical absorption and desorption,Boehm titration,etc.Combined with the results of absorption and desorption of butyl acetate and trimethylamine gas,AC3 was selected as the adsorbent of butyl acetate waste gas.And AC6 was selected as the adsorbent for trimethylamine waste gas.Oxidative modification,high temperature modification and hydrothermal modification were carried out on the two active carbon respectively.The results show that with the increased of oxidant concentration,the content of oxygen-containing groups increased.And the excessive concentration of oxidant causes the collapse of activated carbon skeleton.In N2 atmosphere,as the temperature increases,the oxygen-containing groups decomposed.Under hydrothermal conditions,as the temperature increases,the content of carboxyl groups and lactone groups decreases.And the content of phenolic hydroxyl groups increased.As the result,AC3 modified by hydrothermal at 240? was used to be the absorbent for butyl acetate exhaust gas.And AC6 modified by 5% nitric acid was selected as the absorbent for trimethylamine exhaust gas.The process conditions for adsorption of butyl acetate waste gas were optimized.The temperature was 25?.The inlet concentration was 5.5 mg/L.And the gas velocity was 0.2 m/s.Dry active carbon was used to adsorb the waste gas with a humidity of 0.The adsorption capacity was the largest,up to 32.32%(wt%).The adsorption equilibrium relationship and adsorption kinetics were studied.The Langmuir adsorption isotherm was better than the Freundlish absorption isotherm.The quasi-first order and Bangham equation can describe the adsorption process kinetics appropriately.It indicated that the adsorption process of butyl acetate is mainly the physical adsorption in the pores.The process of butyl acetate desorption was studied.And a staged desorption process was proposed with hot air as desorbent.Under the process,the desorption proportion of butyl acetate reached 99.81%.And the recovery rate reached 89.51%.Under the optimal conditions adsorption and desorption,active carbon can be reused more than ten times.The process conditions for the adsorption of trimethylamine waste gas were optimized.The temperature was 25?.The inlet concentration was 8 mg/L,and the gas velocity is 0.2 m/s,the saturated adsorption capacity of the active carbon was the largest,which can reach 44.51%.And under this condition,the competitive adsorption relationship was studied between trimethylamine and aniline.The results showed that when the concentration of aniline was too high,trimethylamine could replace the aniline waste gas adsorbed.In order to ensure that active carbon has ideal adsorption for both of trimethylamine and aniline,the ratio of trimethylamine to aniline should not exceed 2:1 in the mixed exhaust gas.