Time adapted linear driving force model for gas adsorption onto solids

Abstract

• Frequently used models cannot predict kinetics data for all adsorption pairs. • Introduces a time adapted linear driving force model for adsorption kinetics. • Validates the proposed model with experimental data of various adsorbent-adsorbate pairs. • Proposed model can successfully predict the entire adsorption process. • Diffusion time constant has been calculated for all the studied pairs. Adsorption systems are promising for sustainable energy applications, like a low-grade thermal energy-driven heat pump, gas storage, water desalination, and thermal energy storage. The dynamic uptake of adsorbate onto the porous adsorbent plays a crucial role in determining the performance of these adsorption systems. This paper presents a new kinetics model to precisely describe the adsorption dynamics for different adsorbate – adsorbent pairs. A detailed mathematical derivation of this model, along with validation for several adsorption pairs, is presented in this paper. The most significant drawback of traditional kinetics models such as Fickian diffusion, linear driving force, and semi-infinite model has been their time-dependent deviation from experimental data. The proposed model can predict the adsorption dynamics accurately both during the initial unsaturated condition as well as during the later period when the adsorbent is near its saturated condition. Thus, one can use this model for predicting the adsorption system performance for both short and long cycle times.