Preparation of micro-mesoporous granular cork activated carbon and its adsorption properties to free formaldehyde
[Objective]Activated carbon has attracted much attention in air pollution control with its well-developed pore structure,largely specific surface area and strong adsorption.With increasing awareness of the harm of massively free formaldehyde caused by decoration materials,granular activated carbon with advanced microporous structure has been developed rapidly,and it is critical to develop a kind of micro-mesoporous with high adsorption property for building a healthy indoor environment.The development of a kind of micromesoporous granular activated carbon with high adsorption efficiency has important practical significance for building a healthy indoor environment.[Method]In this study,cork activated carbon(CAC)suitable for adsorption of free formaldehyde was prepared by KOH activation method by using cork which can be repeatedly peeled as raw materials to discuss its influences of different pre-carbonization temperatures,mass ratios of alkali to carbon and activation temperatures on CAC micropore development and adsorption capacity of free formaldehyde.The influences of different pre-carbonization temperature,mass ratio of alkali to carbon and activation temperature on CAC micropore development and adsorption capacity of free formaldehyde were discussed,and the adsorption capacity of CAC to free formaldehyde was increased by expanding its specific surface area and large pore volume.[Result]CAC prepared by KOH etching technology possesses abundant micro-mesoporous structure and specially layered porous structure,with the pore size concentrating within 3 nm,and the number of micropores with a pore size of 0.4 nm being the largest.The layered porous structure of CAC not only increased the specific surface area and pore volume,but also provided more adsorption sites for formaldehyde molecules.The optimum process parameters for preparing CAC were as follows:pre-carbonization temperature was 550℃,mass ratio of alkali to carbon represented 5∶1,activation temperature considered 750℃.Under these conditions,the specific surface area(1 984.08 m2/g)and total pore volume(1.06 cm3/g)of CAC were the largest,the proportion of micropores was as high as 86%,the adsorption capacity of free formaldehyde was 0.276 8 mg/g,and the removal rate was 86.8%.[Conclusion]The preparation of micro-mesoporous activated carbon with layered porous structure with cork as the raw material has great potential for the adsorption of free formaldehyde and other gas pollutants.Its efficient adsorption provides a new possibility for the treatment of gas pollutants,and inspire deeper and basic research for the studying high value utilization of cork and even comprehensive utilization of natural oak forests.
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