Industrial wastewaters contain a multitude of environmentally toxic and harmful pollutants, which when discharged unchecked can cause irreparable damage to the biota. Adsorption has been an exciting method of treatment for the removal of toxic components from industrial effluent. An understanding of isotherm modelling will further the appreciation of the adsorption process behaviour. Sorption rate, thermodynamics, stability, spontaneity and capacity, are all parameters that can be estimated by mathematical modelling using isotherms. Several models exist to simulate and predict adsorption behaviour, each attempting to simplistically represent the underlying process, building on certain assumptions. This paper reviews existing adsorption isotherms and the advancements made by authors in this field, whether it be non-linearization, multi-component accommodation
or parameter replacement. A researcher may apply the model that best suits his or her experimental requirements.