稻壳合成纳米多孔生物炭用于吸附亚甲基蓝

Synthesis of nano-porous biochar from rice husk for adsorption of methylene blue

采用KOH和KOH-NaOH作为活化剂,稻壳为原料,制备出活性生物炭,对亚甲基蓝的吸附表现出优异的性能。研究了单独用KOH活化和KOH-NaOH联合活化时,碱炭比、活化温度和活化时间的影响。结果表明,当KOH和生物炭的质量比为1∶1,活化温度为900℃,活化时间为1h时,活化后的生物炭的吸附能力为314.571mg·g^(-1)。但采用KOH-NaOH联合活化(稻壳∶KOH∶NaOH的质量比为1∶0.3∶0.7),活化温度为800℃,活化时间为1h,在相同的吸附条件下,活化生物炭的吸附容量为350.287mg·g^(-1)。采用扫描电子显微镜、比表面积分析仪和红外光谱仪来表征两种类型的活性生物炭。结果表明,它们的化学成分相似,都具有丰富的孔隙结构,但通过KOH-NaOH联合活化制备的稻壳炭主要是微孔,孔径分布更均匀,这被认为是高吸附能力的主要原因。

Activated biochar was produced from rice husk using KOH and KOH-NaOH as activators,which showed excellent performance on the adsorption of methylene blue.The effects of alkali-carbon ratio,activation temperature and activation time were investigated for the activation of KOH alone and the combined activation of KOH-NaOH.The results showed that when the mass ratio of KOH and biochar was 1∶1,the activation temperature was 900℃and the activation time was 1h,the adsorption capacity of the activated biochar was 314.571mg·g^(-1).Intriguingly,when using the combined activation of KOH-NaOH(the mass ratio of rice husk:KOH∶NaOH was 1∶0.3∶0.7),the activation temperature was 800℃and the activation time was 1h,the adsorption capacity of activated biochar was 350.287mg·g^(-1) in the same adsorption conditions.Scanning electron microscopy,specific surface area analyzer,and infrared spectroscopy were also used to characterized the two type of activated biochars.The results indicated that they were similar in chemical composition and both had a richly developed pore structure,but the rice husk carbon prepared by combined KOH-NaOH activation was predominantly microporous with a more uniform pore size distribution,which was considered to be the main reason for the high asorption capacity.