Surface modification of bentonite and montmorillonite as novel nano-adsorbents for the removal of phenols, heavy metals and drug residues

Montmorillonite (Mt) is one of the eco-friendly and low-cost nano-adsorbents for water and wastewater treat ment. Interactions of Mt. with various modifiers such as surfactants and polymers make it an ideal adsorbent with good selectivity for the removal of phenols, heavy metals and drug residues from water and wastewater. Surface modification can improve the adsorption potential of Mt. due to increasing the number of adsorption sites and functional groups to remove a wide variety of contaminants. This paper shows a general overview of the structure, adsorptive characteristics, and applications of Mt. and modified Mt. (m-Mt). Also, recent progress made in using of natural and modified bentonite and Mt. for removing phenols, heavy metals and pharmaceu ticals from water and wastewater are explained. Furthermore, it discusses the strategies used to increase the adsorption capacity of Mt. by surface modification with cationic surfactants, acids, and polymers. This article delivers an exploration of the current uses of bentonite and Mt. for water and wastewater treatment and encouraging results obtained in this review could aid in the application Mt. and m-Mt for the recovery of high added value compounds and removal of contaminants from aquatic systems.