Study On The Preparation Of Adsorbent Based On Biochar And Molecularly Imprinted Technology And Its Adsorption Performance For Carbon Dioxide

Activated carbon is a kind of cheap,sustainable and resource rich material with unique structure,excellent stability and regeneration performance,showing better carbon dioxide adsorption capacity,and has great application prospects.In this paper,we used pomelo peel,lotus seed,loofah and sunflower as precursors and KOH as activator to prepare four kinds of biochar based activated carbon.Imprinting technology(IT)is a biomimetic molecular recognition technology,which can simulate the recognition mechanism of enzyme substrate and antibody antigen molecules in nature.According to the types of principle,it can be divided into two categories:molecular imprinting(MIT)and ion imprinting(IIP).According to the principle of molecularly imprinted technology,oxalic acid is the template molecule,acrylamide is the functional monomer and glycol dimethacrylate is the crosslinking agent.We have prepared carbon dioxide molecularly imprinted polymer(S-MIP)with sunflower based activated carbon as the carrier and carbon dioxide molecularly imprinted polymer(?-CD-MIPs)with cyclodextrin as the pore forming agent.We have used FT-IR,SEM,TEM,bet and other experimental means.The structure of the adsorption material was characterized.Through the fixed bed experiment,the adsorption performance of the adsorbent was studied,and the adsorption mechanism was preliminarily discussed.Finally,the regeneration performance of the adsorbent was investigated.The main conclusions are as follows:1)The adsorption capacity of carbon dioxide on four kinds of biomass activated carbon was investigated.The structure showed that the ratio of alkali to carbon,adsorption temperature,desorption temperature and carbon dioxide concentration all affected the adsorption capacity.The best conditions of carbon dioxide adsorption on grapefruit peel based activated carbon,lotus flower based activated carbon,Luffa complex based activated carbon and sunflower based activated carbon were as follows:the ratio of alkali to carbon was 1:1,1:1,0.5:1 and 0.75:1 respectively,adsorption temperature is 60?,60?,60? and 60? respectively;the higher the carbon dioxide concentration,the greater the adsorption capacity.Under these conditions,the maximum saturated adsorption capacity of grapefruit peel based activated carbon is 1.15 mmol/g;the maximum saturated adsorption capacity of Rosebud based activated carbon is 1.23 mmol/g;the maximum saturated adsorption capacity of Luffa complex based activated carbon is 1.40 mmol/g;the maximum saturated adsorption capacity of sunflower based activated carbon is 1.39 mmol/g.2)Molecularly imprinted polymers based on sunflower based activated carbon were prepared.The influence of the load of sunflower based activated carbon on the adsorption capacity was discussed,which indicated that the carrier affected the formation of imprinting sites,and then affected the adsorption capacity.In addition,the effects of adsorption temperature,desorption temperature,carbon dioxide concentration and moisture on the adsorption capacity were discussed.Under the optimal adsorption conditions(adsorption temperature:25?;desorption temperature:120?;carbon dioxide concentration:10%),the optimal saturated adsorption capacity is 1.92 mmol/g.The selectivity experiment showed that the molecularly imprinted polymer of sunflower based activated carbon had general selectivity to carbon dioxide.After five cycles of adsorption regeneration experiments,the adsorption capacity is slightly reduced,but it is almost stable,indicating that the material has good reusability.3)The molecularly imprinted polymer ?-CD-MIPs with ?-cyclodextrin as pore forming agent was prepared.The effects of the amount of ?-CD,the adsorption temperature and the presence of water on the CO2 capture performance of ?-CD MIPs were studied.The adsorption capacity of ?-CD MIPS for CO2 decreased with the increase of temperature.When the amount of ?-CD is 1g,the optimal adsorption temperature of ?-CD MIPS is 25?.Under this condition,the ?-CD-MIPs have the largest amount of CO2 saturated adsorption.At the same time,the recycling capacity and selectivity of the adsorbent were also investigated.Under five adsorption/desorption cycles,the loss of adsorption capacity is very small,which proves that the material has stable performance and excellent repeatability.In the case of other gas interference,the adsorption capacity of the adsorbent for CO2 is slightly lower than that of a certain concentration of CO2,and it has good selectivity.