Study On The Preparation,Properties,Application And Mechanism Of Activated Carbon From Sugarcane Rind

According to the recent research progress and the main problems in the preparation of activated carbon from sugarcane rind,the pyrolysis process,influencing factors and pyrolysis kinetics of sugarcane rind were studied by thermogravimetric analyzer.The preparation technology of sugarcane rind activated carbon by mixed acid method was optimized by orthogonal experiment.The effects of the technologic factors of mixed acid concentration,activation temperature and time on the adsorption performance and yield of the activated carbon were studied by single factor experiment.The structure,morphology,surface functional groups and specific surface area and pore structure of sugarcane rind activated carbon were investigated by using the X-ray diffraction（XRD）,scanning electron microscope（SEM）,Fourier transform infrared spectrometer（FT-IR）,and Brunauer-Emmett-Teller（BET）.The effects of initial malachite green concentration,activated carbon dosage,adsorption temperature and time on the removal efficiency of sugarcane rind activated carbon adsorption malachite green wastewater were studied,the adsorption process of malachite green by activated carbon from sugarcane rind was analyzed with adsorption thermodynamics and kinetics model,and the regeneration performance of sugarcane rind activated carbon was studied.The results were showed as follows:（1）When the heating rate was 10℃/min,and the temperature range was from room temperature to 900℃,the pyrolysis process of phosphoric acid/sugarcane rind,phosphoric acid/hydrochloric acid/sugarcane rind,phosphoric acid/hydrochloric acid/oxalic acid/sugarcane rind samples were diviede into three stages,namely dehydration,pyrolysis and carbonization.（2）The fitting coefficients of the first-order reaction model for phosphoric acid/sugarcane rind and phosphoric acid/hydrochloric acid/oxalic acid/sugarcane rind samples at the third stage were all above 0.9.The activation energy and pre-exponential factor of the two samples were 21.80 KJ/mol,6.3×10^-1 min^-1;19.05 KJ/mol,4.6×10^-1 min,respectively.（3）The order of the influence of process factors on the adsorption performance and yield of sugarcane rind activated carbon:activation temperature,oxalic acid concentration,phosphoric acid concentration,activation time and hydrochloric acid concentration.When the concentration of phosphoric acid,hydrochloric acid and oxalic acid were 20 ^vol%,4 ^vol%and 4 ^wt%,and the activation temperature and time were 700℃and 50 min,respectively,the yield of activated carbon from sugarcane rind was 23.22%,and the methylene blue adsorption value of the sample was 19.0 mg/0.1g,which was 2.1times of national wood activated carbon grade one product standard.（4）When other technology conditions remained unchanged,the methylene blue adsorption value of activated carbon from sugarcane rind would increase first and then decrease with increasing in the activator concentration such as phosphoric acid,hydrochloric acid and oxalic acid,activation temperature or time.The yield of the sample would increase first and then remain unchanged with increasing in the phosphoric acid concentration,and would decrease with increasing in the activator concentration such as hydrochloric acid and oxalic acid,activation temperature or time.（5）The sugarcane rind activated carbon samples were amorphous,with well-developed micropore and mesoporous structures.The specific surface area,total pore volume and pore size were 100.9m²/g,0.204 cm³/g and 1.8-50 nm,respectively.There were functional groups such as-OH,O-H,C=C and C-O-C on the surface of the samples.（6）When other conditions remained unchanged,the removal efficiency of malachite green wastewater by sugarcane rind activated carbon would decrease with increasing in initial concentration of malachite green,would increase with increasing in adsorption temperature,and would increase first and then gradually stable with increasing in activated carbon dosage or adsorption time.When the initial concentration of malachite green was 900 mg/L,the dosage of activated carbon was 0.035 g,and the adsorption temperature and time were 25℃and 240 min respectively,the removal efficiency of malachite green wastewater could reach 92.08%,and the adsorption capacity was1183.83 mg/g.After recycling for 6 times,the removal rate of malachite green was76.57%.（7）The adsorption of malachite green by sugarcane rind activated carbon could be divided into three stages:membrane adsorption,intra-particle diffusion and dynamic balance.The isotherm and adsorption kinetics data of sugarcane rind activated carbon fitted well with Langmuir adsorption isotherm model and quasi-second-order kinetic model respectively.The process of malachite green adsorption by activated carbon on sugarcane rind was a spontaneous endothermic reaction,mainly chemical adsorption.The involved forces included hydrogen bonding andπ-πconjugation.