改性生物炭固定床对模拟湖库水体中Mn^(2+)的吸附

Adsorption of Mn^(2+) by Modified Biochar Fixed Bed in Simulated Lakes and Reservoir Waters

湖库是社会生产发展的重要水资源,而湖库饮用水中锰离子(Mn^(2+))的季节性超标成为威胁人类的生活健康和社会安全生产的重要因素之一.首先,开展了NaOH改性生物炭的静态吸附研究,并考察了热解温度(400、 500和600℃)和改性条件(未改性、碱前处理改性和碱后处理改性)对吸附性能的影响,研究表明碱前处理改性能提高生物炭的吸附容量,在400℃时获得最大吸附容量为41.06 mg·g^(-1).之后,开展了改性生物炭固定床对Mn^(2+)的动态吸附研究.结果表明,碱改性生物炭在静态吸附状态下的吸附能力越强,其在固定床动态吸附过程中的穿透点(c_(t)/c_(0)=0.1)和饱和点(c_(t)/c_(0)=0.9)时间越长;当分别提高Mn初始浓度和进水流速时,固定床吸附的穿透点时间由360 min分别缩短至160 min和200 min,饱和点时间由865 min分别缩短至700 min和600 min. Thomas吸附模型能较好地拟合生物炭固定床吸附过程,表明动态吸附过程中,生物炭对Mn^(2+)的去除由化学吸附主导,研究结果可为实际运行提供科学指导.

Lakes and reservoirs are important water resources for human survival and sustainable development. The seasonal excess of manganese ions(Mn^(2+)) in drinking water in lakes and reservoirs has become an important factor threatening human life in health and social safety in production. Firstly, a batch study of NaOH-modified biochar was carried out. The effects of pyrolysis temperature(400, 500, and 600℃) and modification conditions(unmodified, pre-alkali modified, and post-alkali modified) on the adsorption performance of biochar were investigated. The results showed that the alkali pretreatment could improve the adsorption capacity of biochar, and the maximum adsorption capacity of the modified biochar obtained by alkali pretreatment at 400℃ was 41.06 mg·g^(-1). Additionally, the dynamic adsorption characteristics of Mnin the application on the fixed bed were investigated. The results showed that the stronger the adsorption capacity of biochar in the batch experiment, the longer its breakthrough point(c_(t)/c_(0)=0.1) and saturation point(c_(t)/c_(0)=0.9) in the dynamic adsorption process. In addition, when the initial concentration of Mn^(2+)and the influent flow rate were increased, the breakthrough point of the fixed bed was shortened from 360 min to 160 min and 200 min, respectively, and the saturation point was shortened from 865 min to 700 min and 600 min, respectively. The Thomas model could better fit the adsorption process of the fixed bed, indicating that the removal of Mn^(2+)by biochar was also dominated by chemical adsorption. This outcome can provide theoretical guidance for actual operations.