Design,Preparation And Performance Of Carbon-based Materials Based On Sesame Straw

Biomass is one of the important renewable energy sources on the earth.It has the advantages of renewable in a short time and abundant resources.The utilization of biomass energy has both economic and environmental significance.The conversion of biomass into high value-added products is a very complex process,which is affected by the structure,composition,conversion methods and reaction conditions of biomass.Therefore,combined with the structural characteristics of biomass and exploring different transformation methods to improve the utilization efficiency of biomass energy and increase the added value of biomass products has become one of the significant problems to be solved in the utilization of biomass energy.Among a variety of biomass conversion products,porous carbon materials produced by pyrolysis have attracted extensive attention for they can be used in energy,environment and other fields.Due to the porous carbon structure with high specific surface area,the chemical activation method is considered to be the most suitable pyrolysis method at this stage.In the chemical activation method,the selection of appropriate chemical activators in order to improve the adsorption performance of porous carbon materials has become one of the important research directions.In addition,cellulose,the main utilization component of biology,is wrapped by lignin structure which hinders the efficient utilization of biomass.Hence,choosing appropriate methods to remove lignin is also one of the important research directions at present.In view of the above situation,firstly,activated carbon with high performance was designed and prepared by thermochemical conversion technology according to the characteristics of biomass in our work.Through the analysis of adsorption isotherm and adsorption kinetics experiments combined with relevant models,the adsorption mechanism of activated carbon adsorbing antibiotics was systematically studied.Secondly,combined with the structural characteristics of biomass,the photocatalytic degradation of lignin in biomass was carried out,and the influence mechanism of biomass photocatalytic degradation process under different operating conditions such as photocatalyst concentration,p H and irradiation time was studied.The main research contents and results of this paper are summarized as follows:1.Amorphous porous carbons with good adsorption properties were designed and prepared.The amorphous porous carbon was synthesized by pyrolysis in a high temperature tubular furnace.Sesame straw was chosen as precursor.KOH and Ca（OH）₂ were chosen as co-activator.Compared with the traditional activated carbon precursor,sesame straw has the advantages of rich in resources,low price,more economical and environmentally friendly.In addition,the characterization results show that the coactivators KOH and Ca（OH）₂ significantly increase the surface roughness of activated carbon and expand the pore structure,with a specific surface area of 935 m²·g^-1.2.Combined with adsorption experiments,adsorption isotherm models,adsorption kinetic models and DFT calculations,the micro adsorption mechanism of amorphous porous carbon adsorption process was explored.Norfloxacin（NOR）,ciprofloxacin（CIP）and enrofloxacin（ENR）were selected as adsorbents in these experiments.The results showed that the pseudo second-order kinetics and Sips model were more consistent with the experimental adsorption results,which indicated that the adsorption process was mainly controlled by chemical adsorption,and the adsorption process of APBCs was heterogeneous and multilayer.The maximum adsorption capacity(₈8)))was calculated based on the sips model.The values of the three₈8))are 220.36 mg/g,197.78 mg/g and 138.13 mg/g respectively which are significantly higher than the data collected in the literature.Infrared spectrum analysis and DFT calculation showed that there was complexation with carboxylic acid anion,π-πinteraction and hydrogen bond between APBCs and adsorbent.The interactions between these adsorbent and adsorbate can improve the adsorption affinity of APBCs for the above antibiotics.3.The effects of different influencing factors on photocatalytic degradation of lignin were explored.Through single factor experiment,the factors such as catalyst mass concentration,p H of photocatalytic system and irradiation time were optimized to obtain the best degradation conditions:the concentration of catalyst Ti O₂ was 0.8 g/L,the p H of photocatalytic system was10.0 and the irradiation time was 6 hours.Under these conditions,the contents of lignin and hemicellulose in sesame straw degraded from 20.39%and 14.47%to 9.96%and 5.51%respectively,and the content of cellulose increased from 38.24%to 55.43%.In addition,the sesame straw before and after degradation was characterized by SEM,FTIR,XRD and TGA/DTG.The results showed that the structure of sesame straw after photocatalytic treatment was destroyed,and the lignin structure was effectively degraded.