Preparation And Experimental Analysis Of Biomass Activated Carbon By Microwave Irradiation

Activated carbon(AC),as a carbon material containing porous,has been used as an effective adsorption material for the removal of various organic and inorganic pollutants,polar and non polar compounds in water or gaseous environment because of its very developed space structure and huge specific surface area.In recent years,ACs has been widely applied to all fields of human life.This paper mainly takes furfural residue(FR)as raw material,and obtains two kinds of raw materials such as furfural residue(WFR)and alkaline furfural residue(KFR)by different pretreatment processes(including two forms:water washing pretreatment and alkali impregnation treatment),of which three different impregnation ratios are set by KFR,KOH:FR=0.5,1.0 and 1.5,respectively.Activation experiments were carried out using CO2 gas as oxidizing gas.The experimental process was carried out by the electric heating tube furnace and the microwave tube furnace respectively.The activation temperature,the activation time and the impregnation ratio of ACs,the adsorption value of iodine and the adsorption value of methylene blue(MB)were investigated.The results of ACs prepared by electric heating furnace show that the yield of KFRACs is much higher than that of FRAC and WFRAC.The best operation conditions of three kinds of AC are FRAC*(800?,80 min),WFRAC*(850 ?,100 min)and KFRAC*(650?,80 min,IR = 1).For KFRAC*,BET surface area,Langmuir surface area,total pore volume and mesoporous volume are 1962.7 m2/g,2799.5 m2/g,1.12 m3/g and 0.87 m3/g,far higher than FRAC*and WFRAC*.The adsorption value of methylene blue number,iodine number and the yield of activated carbon are 456.6 mg/g,937.6 mg/g and 65.3%respectively.Compared with FRAC and WFRAC,KFRAC has more oxygen functional groups.Then the activated carbon was prepared by microwave irradiation with FR,WFR and KFR as raw materials via microwave irradiation.The effects of activation temperature,activation time and impregnation ratio on the yield,adsorption capacity and surface structure of ACs were investigated.The optimal operating parameters of FR and WFR were determined by the signal to noise ratio(S/N)and variance analysis.At the same time,the preparation conditions of high quality activated carbon were obtained.Secondly,the optimum operating conditions for the preparation of activated carbon by KFR were studied on the basis of single factor experiment.The results showed that the best operating parameters of the three kinds of activated carbon were MFRAC*(800?,40 min),MWFRAC*(800?,100 min)and MKFRAC*(650?,80 min,IR = 1).For MKFRAC*,BET surface area,Langmuir surface area,total pore volume and mesoporous volume are 833.7 m2/g,1175.5 m2/g,0.50 m3/g and 0.10 m3/g,far higher than MFRAC*and MWFRAC*.The adsorption value of methylene blue number,iodine number and the yield of activated carbon are 472.6 mg/g,1053.1 mg/g and 56.8%respectively.On the basis of the above two parts,the effects of microwave irradiation heating and traditional heating on the adsorption properties and surface structure of ACs under the same raw materials and operating parameters were carried out.The results showed that KFR had high adsorption and specific surface area in the two heating ways.The ACs prepared by traditional heating has high specific surface area and total pore volume.However,the ACs prepared by microwave heating has higher iodine adsorption value and MB adsorption value than that of ACs prepared by traditional heating,which may be attributed to the difference in the surface properties of activated carbon and the difference of surface morphology and structure.This paper focuses on the study of the optimum operating parameters of the preparation of high quality activated carbon by microwave heating and traditional heating of three kinds of raw materials of FR,WFR and KFR,as well as the influence of different pretreatment methods and heating modes on the adsorption properties and surface structure of activated carbon,and the internal reasons are analyzed.It is feasible to prepare activated carbon from furfural residue as biomass waste.This not only achieves the reuse of biomass wastes,but also creates more economic value.At present,the research of furfural residue as the precursor of activated carbon is not much,so the research on furfural residue is beneficial to increase the understanding of furfural residue resource.And it can lay the experimental foundation and theoretical foundation for further research of furfural residue.