Microwave Assisted Preparation Of Activated Carbon From Lignin Materials And Its Adsorption Of RB-19

Reactive dyes due to their high toxicity and refractory characteristics,has been causing serious pollution to the environment,therefore,removal of reactive dyes in water is of great significance.Activated carbon?AC?as an adsorbent,use agricultural wastes?almond shell and macadamia nut shell?as raw materials to prepare AC for RB-19 dye adsorption in water,preparation conditions were optimized by response surface method.To improve the directional removal effect of target adsorption properties,the components of almond shell and macadamia nut shell were determined,the relationship between different components and the performance of the structure of ACs was discussed,therefore achieve the directional preparation,directional adsorption purposes.In general,ACs will be discarded or burned after the first use,with the goal of improve the economic benefits of AC,the research of magnetic supported AC particles and regeneration of AC,the results are as follows:With Xinjiang almonds shells?AS?as raw material,use microwave radiation and the use of ZnCl2 as a chemical activator to prepare almond shell-based activated carbon?ASAC?.And use the response surface method to study the influence of different prepare conditions of ASAC for methylene blue?MB?dye adsorption.The optimum conditions of ASAC preparation were mass?ZnCl2/AS?ratio of 3:1?wt.%?,microwave heating time of 15 min and microwave power of 900 W.The yield of optimized ASAC was 39.67%.ASAC was also characterized by N2 adsorption-desorption,scanning electron microscopy,Fourier-transform infrared spectrometry,X-ray photoelectron spectroscopy and point of zero charge measurement.The result show that,the surface of ASAC has a relatively developed pore structure,the BET surface area of 839.60 m2/g and a total volume of 0.406 cm3/g,and the carbon content increased while oxygen content is on the decline.The adsorption behavior of ASAC for RB-19 was fitted well to the pseudo-second-order model and the Langmuir isotherm model.Studies have shown that the use of almonds shell as a raw material to preparation AC is promising and prospects for development.Macadamia nut shell?MNS?was used as raw material to prepare macadamia nut shell-based activated carbon?MNSAC?by KOH activate microwave radiation under the response surface method optimization.The optimum conditions for preparing MNSAC through response surface method were as follows: microwave power 600 W,activation time 10 min,and mass ratio?KOH: MNS?2:1.MNSAC and MNS were characterized by SEM,FTIR,XPS and so on.The results show that pores and functional groups on the material surface significantly changed after activation,the Brunauer–Emmet–Teller surface area of MNSAC was 876.77 m2/g,and the total volume was 0.533 cm3/g.And on this basis,the effect of different factors in adsorption performance of RB-19 onto MNSAC was studied.The maximum adsorption capacity of RBBR onto MNSAC reached 376.81 mg/g at 293 K.In addition,the adsorption of RBBR onto MNSAC increased with the increase in initial dye concentration,contact time,and solution temperature and it was also favored in acidic medium.And the adsorption of RB-19 onto MNSAC fitted to the pseudo-second-order kinetic model and the Langmuir isotherm.The sorption process was spontaneous and endothermic.Results suggested that microwave radiation is an efficient and rapid method for preparing MNSAC for effective removal of RB-19 and has laid a certain foundation for its extensive use.In order to study the relationship between different material composition and structure of AC,the contents of cellulose,lignin and hemicellulose in almonds shell and macadamia nut shell have been determined.Choose the difference mass ratio of cellulose and lignin to prepare ACs,the ACs were marked as AC-1,AC-4,AC-6,AC-8 and AC-9.Their surface structure,chemical composition and adsorption performance were characterized.Among these ACs,AC-4 have a good mesoporous structure,and the adsorption properties of RB-19 onto AC-4 was the best.The results show that the higher the content of cellulose in the preparation of activated carbon,the better the pore structure of activated carbon,the higher the adsorption capacity of RB-19,and the high content of cellulose will also affect the formation of pore structure of activated carbon.The adsorption behavior is spontaneous,endothermic reaction,conform to the pseudo-second-order kinetic model and the Langmuir isotherm.Mix AC and Fe₃O₄ in proportion,loading the magnetic material Fe₃O₄ onto AC under the condition of ultrasonic,and studied the adsorption performance of RB-19 onto magnetic AC.Results show that the removal rate of RB-19 on magnetic AC was 86.91%,using the magnetic separation method to recycle magnetic AC and assisting with microwave heating method for the regeneration process.The recycle number of magnetic AC was up to 5 times and the final removal rate was 76.45%.Therefore,activated carbon load magnetic material greatly reduce the cost of recycling,microwave-assisted regeneration of magnetic AC is an effective regeneration technology,and then improved the market economic benefits.