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为了解煤胶体对汞的吸附动力学特性,采用沉降法和离心法提取由霍林河采集煤样中的煤胶体(0~2、2~5、5~10μm),采用批量实验对不同粒径和不同温度下,煤胶体对汞的吸附动力学特性进行了研究。结果表明:煤胶体对汞的吸附反应为吸热反应,以化学吸附为主,其吸附动力学过程可用准二级动力学方程和双室模型很好的描述。煤胶体对汞的平衡吸附量随粒径的减小和温度的升高而逐渐增大,不同粒径煤胶体受温度影响的大小关系为(5~10)μm>(2~5)μm>(0~2)μm。煤胶体对汞的吸附从初始阶段到达到表观平衡,快速吸附均占据优势。在表观平衡时,粒径越大,快速吸附的贡献率越小。煤胶体对汞的吸附反应速率随温度升高和粒径减小而增大。温度越高、粒径越小,快速吸附速率越大;而慢速吸附速率则随温度升高和粒径增大而增大。汞在0~2μm和2~5μm煤胶体上的吸附过程,粒内扩散是其主要控速步骤;而对于5~10μm的煤胶体,膜扩散是主要控速步骤。
In order to understand the adsorption kinetics of mercury on coal colloids, the coal colloids (0 ~ 2, 2 ~ 5, 5 ~ 10μm) collected from Huolinhe were extracted by sedimentation and centrifugation. Diameter and different temperature, coal colloid mercury adsorption kinetics characteristics were studied. The results show that the adsorption of mercury by coal colloid is endothermic, which is dominated by chemisorption. The adsorption kinetics can be well described by quasi - second order kinetic equation and two - compartment model. The equilibrium adsorption capacity of coal colloid to mercury gradually increases with the decrease of particle size and temperature, and the size dependence of temperature on coal colloids with different particle sizes is (5 ~ 10) μm> (2 ~ 5) μm> (0 ~ 2) μm. Coal colloid mercury adsorption from the initial stage reached an apparent equilibrium, rapid adsorption are dominant. Apparent equilibrium, the larger the particle size, the smaller the contribution rate of rapid adsorption. The adsorption rate of mercury to coal colloids increases with increasing temperature and particle size. The higher the temperature, the smaller the particle size, the faster the adsorption rate, while the slow adsorption rate increases with the temperature and particle size. Adsorption process of mercury on 0 ~ 2μm and 2 ~ 5μm coal colloids, intragranular diffusion is the main rate-controlling step; while for 5 ~ 10μm coal colloids, membrane diffusion is the main rate-controlling step.