Preparation of magnesium oxide doped modified activated carbon and its adsorption properties and mechanism toward color plates printing VOCs
Aiming at the adsorption capacity reduction of VOCs on activated carbon due to the competitive adsorption in industrial applications,coal-based activated carbon was modified with magnesium oxide doped by impregnation to improve the adsorption capacity for multicomponent adsorption,taking toluene,ethyl acetate,and isopropanol as the representatives of VOCs in color plates printing.The results showed that the optimal doping ratio and calcination temperature of magnesium oxide were 1％and 450 ℃,respectively.Compared with the original activated carbon,the adsorption capacity of modified activated carbon to toluene,ethyl acetate and isopropanol in single-component adsorption experiments increased by 42％,18％and 25％,respectively,the substitution amount of weak adsorbates in the binary adsorption experiments decreased from 51％,55％and 38％to 24％,44％and 33％,respectively,and the adsorption capacity increased by 34％～80％,indicating that the binary competition was weakened.The adsorption capacity of AC/MgO-1％remained above 92.68％after five regeneration cycles.DFT calculations showed that the adsorption process of toluene,ethyl acetate,and isopropanol,toluene was a type of strong adsorbate adsorbed on AC,while on magnesium oxide,isopropanol was a type of strong adsorbate,and magnesium oxide doping could reduce the binary competition effect to a certain extent.SEM,BET,FTIR,and XRD characterization results indicated that doping of magnesium oxide decreased the specific surface area,but it increased the polar functional groups and active sites,and improved the adsorption capacity.
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