『Abstract
　The retention (or release) of a liquid compound on a solid controls the mobility of many substances in the environment and has been quantified in terms of the “sorption isotherm”. This paper does not review the different sorption mechanisms. It presents the physical bases underlying the definition of a sorption isotherm, different empirical or mechanistic models, and details several experimental methods to acquire a sorption isotherm. For appropriate measurements and interpretations of isotherm data, this review emphasizes 4 main points: (i) the adsorption (or desorption) isotherm does not provide automatically any information about the reactions involved in the sorption phenomenon. So, mechanistic interpretations must be carefully verified. (ii) Among studies, the range of reaction times is extremely wide and this lead to misinterpretations regarding the irreversibility of the reaction: a pseudo-hysteresis of the release compared with the retention is often observed. The comparison between the mean characteristic time of the reaction and the mean residence time of the mobile phase in the natural system allows knowing if the studied retention-release phenomenon should be considered as an instantaneous reversible, almost irreversible phenomenon, or if reaction kinetics must be taken into account. (iii) When the concentration of the retained substance is low enough, the composition of the bulk solution remains constant and a single-species isotherms often sufficient, although it remains strongly dependent on the background medium. At higher concentrations, sorption may be driven by the competition between several species that affect the composition of the bulk solution. (iv) the measurement method has a great influence. Particularly, the background ionic medium, the solid/solution ratio and the use of flow- through or closed reactor are of major importance. The chosen method should balance easy-to-use features and representativity of the studied natural conditions.』

Contents
0. Introduction
1. Definition
2. Reaction kinetics and thermodynamic equilibrium
　2.1. Relation between thermodynamics and kinetics
　2.2. Kinetic hysteresis and pseudo-irreversibility
3. Classification and modeling of the isotherms
　3.1. The four main types of isotherms
　　3.1.1. The “C” isotherm
　　3.1.2. The “L” isotherm
　　3.1.3. The “H” isotherm
　　3.1.4. The “S” isotherm
　3.2. Modeling of concave isotherms
　　3.2.1. The Freundlich models
　　　3.2.1.1. Simple Freundlich model
　　　3.2.1.2. Modified Freundlich model for competitive adsorption
　　3.2.2. The Langmuir models
　　　3.2.2.1. Simple Langmuir model
　　　3.2.2.2. Modified Langmuir models for multisite or competitive adsorption
　3.3. Generalized modeling of any isotherm
　3.4. Isotherms of uncharged organic compounds
　3.5. The ion exchange isotherms
　3.6. Surface complexation models
　3.7. How to choose among so many models?
4. Experimental methods
　4.1. Influence of the experimental conditions
　　4.1.1. The solid/solution ratio
　　4.1.2. Closed reactor versus open flow
　　4.1.3. The composition of the background solution
　4.2. Description, advantages, and disadvantages of the methods
　　4.2.1. The batch method
　　4.2.2. The flow-through methods
　　　4.2.2.1. The stirred flow-through reactor
　　　4.2.2.2. The repacked column
　　　4.2.2.3. The zero-length column
5. Conclusion
Acknowledgements
References