熔盐热裂解水稻秸秆制备活性炭及其吸附性能

PREPARATION AND ADSORPTION PROPERTY OF ACTIVATED CARBON FROM RICE STRAW BY PYROLYSIS IN MOLTEN SALT

以ZnCl2-KCl混合熔盐（ZnCl2和KCl的物质的量之比为7：6）热裂解水稻秸秆并进一步用ZnCl2活化热裂解残炭得到活性炭，考察热裂解温度、N，流量、活化时间、活化温度、盐炭比和原料粒径等因素对制备活性炭的得率和吸附性能的影响。结果表明：试验条件下活性炭得率变化不大，均大于30％，但其碘吸附值、亚甲基蓝吸附值则变化明显；450℃、N2流量为150L／h是较佳热裂解条件。活化过程中，活化温度、活化时间和盐炭质量比均对活性炭的吸附性能存在影响，影响程度依次减小，最佳活化条件为活化温度600℃、活化时间1h、活化盐炭质量比3；在20～100目范围内，随着原料粒径的减小，相同条件下制得的活性炭的碘吸附值和亚甲基蓝吸附值均增大。最优试验条件下所制备活性炭的亚甲基蓝吸附值为118．31mg／g，碘吸附值为721．42mg／g，比表面积为1675．9m2／g。

Preparation of activated carbon from agricultural wastes is an important research area for clean biomass utilization. The rice straw was pyrolyzed in a mixed ZnC12-KC1 molten salt with molar ratio of 7：6, and the residual carbon was further activated by ZnC12 to obtain activated carbon. The effects of pyrolysis temperature, nitrogen flow rate, activation temperature, activation time and particle size of raw material on the yield and adsorption property of obtained activated carbon were studied. The yields of activated carbon were higher than 30% in experimental condition, which were almost unaffected by process parameters, however the iodine number and methylene blue adsorption capacity of activated carbon showed obvious variation with these factors. The temperature of 450 ~C with nitrogen flow rate of 150 L/h was the optimum pyrolysis condition. The temperature, time and the ratio of the activated salt （ZnC12 ） to the pyrolysis residual carbon in activation process showed an obvious impact on the ultimate products, the influence reduced in turn. The optimum activation condition was 600 ~C for 1.0 h with a ZnC12 to residual carbon ratio of 3. Furthermore, the iodine number and the adsorption capacity of methylene blue of the obtained activated carbon increased with decreasing particle size when the particle size was in the range of 20 to 200 meshes. The iodine number, the adsorption capacity of methylene blue, and the specific surface area of the obtained activated carbon under the optimum condition were 118.31 mg/g, 721.42 mg/g and 1675.9 mZ/g, respectively.