Structural Implications of Modified Montmorillonite in the Enhanced Adsorption of Methylene Blue

Abstract:

Dye contamination causes significant damage to aquatic flora and fauna and can enter the human ecosystem. One of the most important sources of dye contamination is the textile industry. To address the decade-long environmental challenge, several removal techniques have been developed; among them, adsorption is well known for its versatility. The greatest challenge is selecting the right adsorbent for the right dye. Recent advances in surface-tuning of adsorbents provide a means to facilitate dye removal. This review explores the use of novel surface-modified montmorillonite (a cost-effective adsorbent) for the removal of the methylene blue dye. In particular, emphasis has been given to the basic morphological changes, along with alterations in the interlayer of montmorillonite clay, throughout various modification protocols, strategically transforming montmorillonite into hydrogel membranes, composite materials, or nano-sized particles to facilitate maximum adsorption of methylene blue from water. The role of surface functionalities for a better understanding of the adsorption mechanism, dye- adsorbent interaction, along with alteration of the surface charge of the adsorbent upon variation in pH of the medium, zeta potential, and thermal stability are discussed. Furthermore, the critical factors affecting the viability of these adsorbents, owing to their contribution to sustainable development and potential for industrial use, have been explored.