炭化/活化温度对碳酸钾活化玉米芯生物炭吸附苯的性能影响  

Effect of carbonization/activation temperature on benzene adsorption by potassium carbonate activated corncob biochar

作　　者：黄钰坪 王登辉[1] HUANG Yuping;WANG Denghui(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,陕西西安710049

出　　处：《煤炭学报》2023年第6期2388-2396,共9页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51906193)。

摘　　要：生物炭作为一种新兴的碳质吸附剂,具有良好的VOCs控制功能。以玉米芯为原料,制备了一系列生物炭(BCx)和碳酸钾活化生物炭(KBC-x-y)(其中,x为炭化温度,y为活化温度)用于吸附苯。利用热重分析、氮气吸附-脱附、扫描电镜(SEM)以及元素分析(EA)等方法获得了生物炭(质)样品的热解特性、比表面积、孔容孔径、表面形态及原子占比等,通过吸附实验考察炭化温度/活化温度对生物炭吸附苯的影响。结果表明:碳酸钾活化后的生物炭比表面积最高可达576.76 m^(2)/g,孔容积为0.325 m^(3)/g,对苯的最大吸附量达到82.51 mg/g(较未活化生物炭提升2.9倍);炭化温度与吸附能力呈现正态分布的趋势,吸附能力随着炭化温度的升高而增强,但过高的炭化温度(> 800℃)会导致气孔堵塞、数量减少,比表面积降低,吸附能力下降;低温/高温炭化下,生物炭吸附能力随活化温度变化呈现出相同趋势;高温炭化后(800℃),最佳活化温度为400℃(KBC-800-400),活化温度太高会导致微孔孔壁破碎以及挥发物的烧结效应,从而降低吸附能力,较低的活化温度未能使K2CO3在炭表面充分反应;低温炭化后(400℃),最佳活化温度为(800℃),低温炭化高温活化生物炭(KBC-400-800)吸附性能优于高温炭化低温活化生物炭(KBC-800-400),可能是因为在低温炭化情况下,较高的活化温度有利于碳酸钾参与活化过程反应。As a new kind of carbonaceous adsorbent,biochar has a good function of controlling VOCs.A series of biochar(BCx)and potassium carbonate activated biochar(KBC-x-y)were pre-pared from corncob for benzene adsorption.Thermogravimetric analysis,nitrogen adsorption-desorption,scanning electron microscopy(SEM)and elemental analysis(EA)were used to char-acterize the pyrolytic properties,specific surface area,pore volume and pore size,surface mor-phology and atomic percentage of the biochar(mass)samples.The effects of carboniza-tion/activation temperature on benzene adsorption were investigated by adsorption experiments.The results show that the specific surface area of biochar modified by potassium carbonate is up to 576.76 m^(2)/g,the pore volume is 0.325 m^(3)/g,and the maximum adsorption capacity of benzene is up to 82.51 mg/g (2.9 times higher than that of unmodified biochar). The carbonization temperature and adsorption capacity show a trend of normal distribution. The adsorption capacity increases with the increase of carbonization temper-ature, but the high carbonization temperature above 800 ℃ will lead to the clogging of pores, decrease in number, de-crease in specific surface area and decrease in adsorption capacity. The adsorption capacity of biochar shows the same trend with the activation temperature under low/high carbonization temperature. After high-temperature carbonization (800 ℃), the optimum activation temperature is 400 ℃ (KBC-800-400). If the activation temperature is too high, it will lead to the fracture of micropore wall and the sintering effect of volatiles, thus reducing the adsorption capacity. Lower ac-tivation temperature fails to make K2CO3 fully react on the carbon surface. After low-temperature carbonization (400 ℃), the optimal activation temperature is (800 ℃). The adsorption performance of low-temperature carbonized high-temperat-ure activated biochar (KBC-400-800) is better than that of high-temperature carbonized low-temperature activated biochar (KBC-800-400). It is possib

关 键 词：生物质 活化生物炭 炭化温度 活化温度 吸附性能 

分 类 号：TK114[动力工程及工程热物理—热能工程]