基于势理论对比泥页岩中主要黏土矿物吸附特征

Comparative Study on the Adsorption Character in Shale's Main Clay Minerals Based on Potential Theory

利用吸附势理论对泥页岩中4种主要黏土矿物:蒙脱石、高岭石、绿泥石及伊利石吸附特征进行了描述,同时加入石英岩作为对比样。在吸附势分析中重点探讨了吸附量a、微分吸附功A、特征能量E及特征系数n间的关系。结果表明,随吸附量的增加,微分吸附功降低,微分吸附功可以用来大体表征吸附各阶段变化特征。对于5种无机矿物,n的最佳值在1.5附近;特征能量随温度升高发生略降。对各矿物吸附过程中吸附热及吸附熵进行了计算并讨论,结果表明,随着吸附的进行,不同矿物吸附热及吸附熵发生不同变化,表明吸附过程的复杂性。对于黏土矿物,吸附热及吸附熵绝对值满足:蒙脱石>高岭石>绿泥石>伊利石,与最大吸附量结果一致;同时不同种类黏土矿物的孔隙体积与吸附热及吸附熵绝对值之间具有较好的正相关性,因此吸附热及吸附熵可用来表征不同种类黏土矿物的吸附能力。

Based on the adsorption potential theory, the adsorption characteristics of four kinds of clay minerals were described, i. e. Montmorillonite, Kaolinite, Chlorite, and Illite, in clay shales, meanwhile adding quartzite as control sample. Adsorption amount a, differential adsorption work A, characteristic energy E, characteristic coefficient n in adsorption potential analysis were focud on. The results show that the differential adsorption work decreases as the adsorption energy increases, which can generally represent the change features during each stage; the optimum value of n is around 1.5 for five kinds of inorganic minerals ; E slightly decreases as the temperature increases. The adsorption heat and adsorption entropy in the adsorption process of each mineral are calculated and discussed, and the outcome indicates that the adsorption heat and adsorption entropy change differently in different minerals, showing the complicacy of adsorption process; for clay minerals, the absolute values of adsorption heat and adsorption entropy can meet that Montmorillonite 〉 Kaolinite 〉 Chlorite 〉 Illite, in line with the result of maximum adsorption; in the meantime, the porosity volume has good positive correlation with the absolute values of adsorption heat and adsorption entropy for different kinds of clay minerals. Therefore, the adsorption heat and adsorption entropy can be used to represent the adsorption capacity.