comprehensive review on the adsorption properties of clay minerals for enhanced removal of toxic dyes and heavy metals

Adsorption, a well-known surface phenomenon, is an effective and environmentally friendly method for purifying effluents, allowing for the removal of a wide variety of impurities and contaminants. this process relies on mass transfer, where a solid can selectively extract dissolved components from an aqueous solution by attracting solute molecules to its surface. clay minerals and modified clays are particularly effective as adsorbents for capturing metal ions and various dyes present in wastewater. these natural, non-toxic, and cost-effective materials are widely used in water treatment due to their distinctive properties: large surface area, better cation exchange capacity, and their ability to adsorb pollutants. this article provides an overview of the different types of natural clays (in raw and modified forms), their crystal structures, classifications, and their physical and chemical characteristics. it also provides a detailed discussion of the various methods used to modify clay for improved results, as well as the factors that influence the adsorption process, such as ph, temperature, contact time, and the initial concentration of contaminants. finally, the review highlights the adsorption capacity and efficiency of different clay types for the removal of various contaminants from water particularly dyes and heavy metals.