微波辅助碳酸钾活化制备玉米秆基活性生物炭

Microwave Assisted Preparation of Activated Biochar with Potassium Carbonate Activation from Cornstalk

以碳酸钾为活化剂、少量活性炭为吸波剂,在氩气保护下对玉米秸秆进行微波加热制备活性生物炭。采用比表面积(BET)、扫描电镜和能谱(SEM和EDS)及化学检测的方法,研究了微波加热过程中生物炭孔隙度的变化规律,考察了温度、活化剂(K2CO3)配量、微波功率和保温时间对生物炭吸附性能及产率的影响。结果表明,微波加热制备活性生物炭的最佳条件为:温度650℃、活化剂(K2CO3)配量150%、微波功率700W、保温时间5min。此条件下获得产率为28.1%的活性生物炭,具有发达的多级孔隙结构,比表面积1036.7m2/g;而且此生物炭吸附性能较好,其中碘吸附值1238.7mg/g,亚甲基蓝吸附值254mg/g,优于木质净水用活性炭国家一级标准(GB/T 13804.3-1999)。

Activated biochar was prepared by microwave heating of the cornstalk,with potash as activator,a little activated carbon as wave-absorber and argon as protective gas.By BET,SEM,EDX and chemical analysis,the variation of biochar porosity was discussed during the process of microwave heating,and the effects of heating temperature,percentage of activator(K2CO3),microwave power and holding time on adsorption properties and the yield of biochar were investigated.The results show that the optimum conditions for the activated biochar preparation by microwave heating are temperature of 650℃,K2CO3 content of 150%,microwave power of 700 Wand holding time of 5min.Under the optimum conditions,activated biochar with the yield of 28.1% can be obtained.The activated biochar has a sophisticated multiple-level pore structure with specific surface area of 1036.7m2/g,the iodine adsorption value of 1238.7mg/g and the methylene blue adsorption value of 254mg/g,being advantageous over that of National Primary Standards of wood activated carbon used for water purification(GB/T 13804.3-1999).