改性杨木屑对水溶液中NO2-的吸附研究

Studies on the Adsorption of NO_2^- in Aqueous Solution by the Modified Poplar Sawdust

以杨木屑为原料,在N,N-二甲基甲酰胺中与环氧氯丙烷、二甲胺分别反应制备叔胺型吸附材料,研究了吸附材料对中溶液中NO_2^-吸附性能。结果表明,溶液初始NO_2^-的质量浓度50 mg/L、pH=7.0、吸附材料用量3.5 g/L、25℃,能吸附水溶液中90%以上的NO_2^-。酸性体系不利于NO_2^-的吸附,pH>6.91,对溶液中NO_2^-的吸附大于94%;吸附材料对水溶液中NO_2^-的吸附是快速吸附过程,20 min对溶液中NO_2^-的吸附即可达到98.86%。吸附材料对水溶液中NO_2^-的等温吸附符合Langmuir和Freundlich等温吸附模型。最大吸附容量随吸附温度的升高而降低,相对较低的温度有利于对水溶液中NO_2^-的吸附。拟2级模型能较好地描述改性木质纤维素对水溶液中NO_2^-的吸附过程。

The poplar sawdust using as raw material reacted with epichlorohydrin and dimethylamine sequentially, the adsorption material with tertiary amine group was prepared, and its adsorption character to NO2- existed in water was investigated. The results indicated that, 90% of NO2- in the solution of initial mass concentration of 50 mg/L was adsorbed at pH=7.0, 25 ℃ and the addition of the adsorption material of 3.5 g/L. Acidic system was disadvantage for the adsorption of NO2- , and the adsorption percentage of NO2- was over 94% at pH6.91. It was a fast sorption process, which 98.86% of NO2- in solution was adsorbed at 20 min. The adsorption of NO2- fitted to the Langmuir and Freundlich isothermal adsorption model. The maximum adsorption capacity decreased with the adsorption temperature increase, which the relative low temperature helped the adsorption of NO2- from aqueous solution. The pseudosecond order kinetic model would describe the adsorption process of NO2- with the modified poplar sawdust.