Developing the new kinetics model based on the adsorption process: From fitting to comparison and prediction

Dexin Fang; Xianquan Zhuang; Liping Huang; Qian Zhang; Qiushi Shen; Lei Jiang; Xiaoyi Xu; Fangying Ji

doi:10.1016/j.scitotenv.2020.138490

Developing the new kinetics model based on the adsorption process: From fitting to comparison and prediction

Sci Total Environ. 2020 Jul 10:725:138490. doi: 10.1016/j.scitotenv.2020.138490. Epub 2020 Apr 6.

Authors

Dexin Fang¹, Xianquan Zhuang², Liping Huang³, Qian Zhang³, Qiushi Shen³, Lei Jiang³, Xiaoyi Xu⁴, Fangying Ji⁵

Affiliations

¹ College of Environment and Ecology, Chongqing University, Chongqing 400045, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
² College of Environment and Ecology, Chongqing University, Chongqing 400045, China.
³ College of Environment and Ecology, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China.
⁴ School of Environmental Science and Engineering, Suzhou University of Science and Technology, Jiangsu 215009, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
⁵ College of Environment and Ecology, Chongqing University, Chongqing 400045, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China. Electronic address: jfy@cqu.edu.cn.

PMID: 32302849
DOI: 10.1016/j.scitotenv.2020.138490

Abstract

In this study, an intrinsic kinetics model was proposed to simulate the adsorption process. The kinetics model was established based on the collision theory, where the available adsorption site and residual adsorbate concentration were considered. The model specifically highlights the significance of initial conditions in its equation. The initial reaction condition is expressed by the model parameter ξ, which includes four factors: concentration, volume, adsorbent dosage and adsorption capacity. The applicability of this model was mainly explored with the phosphate adsorption process by layered double hydroxides (LDH). Experimental results indicate that, at a certain initial condition, the intrinsic kinetics rate coefficient exhibits a superior stability, making the adsorption rate become comparable among different materials. On this basis, the kinetics rate coefficients of 60 materials were compared, and the LDH was proved to be advantageous in phosphate removal rate. Additionally, the intrinsic kinetics model was successfully applied to predict the phosphate adsorption kinetics under a wide range of initial conditions. The predicted concentration throughout the entire adsorption process is well consistent with the evolution of experimental data. This model is an effort to advance the kinetics analysis from fitting to comparison and prediction.

Keywords: Adsorption kinetics; Collision theory; Initial condition; Kinetics rate coefficient; Vacancy.