| As a waste of making coffee,coffee grounds account for about two-thirds of the total mass of coffee beans.In most cases,coffee grounds are directly discarded,causing waste of resources.With the annual rise in global coffee consumption,the waste of coffee grounds has become more serious.Studies have shown that coffee grounds have a high carbon content and can be used as a suitable raw material for the preparation of activated carbon.Preparation of coffee grounds into activated carbon,can not only ease energy pressures in today’s society,make full use of biomass energy,but also turn the waste coffee grounds into treasure,with a lower cost to prepare a better performance of activated carbon.In this paper,the water vapor activation method in the physical activation method was used to prepare the coffee grounds activated carbon,and the chitosan was loaded on the coffee grounds activated carbon skeleton to obtain the activated carbon with antibacterial properties.The specific research contents and conclusions are as follows:(1)Water vapor was used as an activator to activate the coffee grounds for activated carbon.Based on thermogravimetric analysis,the carbonization temperature was first determined.Then the three factors of holding time,activation temperature and activation time were investigated by orthogonal method.The iodine value and yield of the coffee grounds activated carbon finally determined that the optimum process was carbonization temperature of 450°C,carbonization time of 1 h,holding time of 1.5 h,activation temperature of 650°C,and activation time of 1 h.The coffee grounds activated carbon prepared under the conditions have a specific surface area of 624.4 m~2/g,a total pore volume of 0.3233 cm~3/g,an average pore diameter of 0.545 nm,and the activated carbon contains more micropores.The micropore specific surface area and pore volume account for 82%and 64%of the total activated carbon respectively.And it is suitable for adsorption of small molecular substances.(2)The coffee grounds activated carbon prepared under the optimal process was compared with the commercially available iodine-producing activated carbon for oil absorption comparison experiments,and the oil absorption,oil absorption rate and selective adsorption were compared.The results showed that the adsorption capacity of activated carbon on coffee grounds was 3 mL/g.It had obvious selective adsorption on oil,and the overall performance was better than that of commercial activated carbon.(3)The coffee grounds activated carbon and the chitosan solution were miscible,and the chitosan was successfully attached to the activated carbon skeleton by simple physical impregnation.Besides,the preparation method was simple and imparted antibacterial ability to the coffee ground residue activated carbon.And the original activated carbon structure was not damaged.The antibacterial coffee grounds activated carbon can not only physically adsorb free bacteria,but also release antibacterial components.The antibacterial rate of the diluted liquids of 10~5 and 10~6 reached100%,and the inhibition zone width of the two kinds of bacterial liquids diluted 10~3 times were more than 1mm,showing a good antibacterial effect.(4)The pH of the coffee grounds activated carbon prepared in this experiment was 7.25,which is weakly alkaline.In the preliminary application,it can be directly added to the soap base without washing,and the prepared soap had a certain antibacterial oil control effect. |
