This work presents an activity-based formulation for Langmuir adsorption isotherm. Treating adsorption as a chemical reaction between the gas molecule and the adsorption vacant site, the classical Langmuir isotherm model expresses the reaction in terms of the species concentrations. Designed to capture the surface heterogeneity, the proposed thermodynamic Langmuir isotherm model substitutes the species concentrations with the species activities and calculates the species activity coefficients with the adsorption non-random two-liquid activity coefficient model. The resulting isotherm model accurately represents pure component adsorption isotherms for gases with wide varieties of adsorbents including silica gels, activated carbons, zeolites and metal organic frameworks at various temperatures. With three physically meaningful parameters, the model outperforms the classical Langmuir isotherm model for the 98 isotherms of 33 systems examined.

中文翻译：

---

基于活性的Langmuir吸附等温线配方

这项工作提出了基于活性的Langmuir吸附等温线配方。将吸附视为气体分子与吸附空位之间的化学反应，经典的朗缪尔等温线模型以物种浓度表示反应。为了捕获表面的非均质性，建议的热力学Langmuir等温线模型将物种浓度替换为物种活性，并使用吸附非随机两液活度系数模型计算物种活度系数。所得的等温线模型准确地代表了在各种温度下具有多种吸附剂（包括硅胶，活性炭，沸石和金属有机骨架）的气体的纯组分吸附等温线。有了三个对身体有益的参数，