Nanoscale Water Behavior and Its Impact on Adsorption: A case study with CNTs and Diclofenac

TL;DR

This study uses molecular dynamics simulations to investigate how nanoscale water behavior affects the adsorption of pharmaceuticals on carbon nanotubes, revealing hydration layers' influence on contaminant removal efficiency.

Contribution

It provides new insights into the role of interfacial water in nanomaterial-based water purification, specifically analyzing water's structuring and its impact on adsorption dynamics on CNTs.

Findings

Hydration layers around CNTs significantly influence adsorption accessibility.

Higher energy barriers for adsorption are observed in DWCNTs due to stronger water-surface interactions.

Understanding nanoscale water behavior can guide the design of more effective nanomaterials for water purification.

Abstract

Water is a fundamental component of life, playing a critical role in regulating metabolic processes and facilitating the dissolution and transport of essential molecules. However, the presence of emerging contaminants, such as pharmaceuticals, poses significant challenges to water quality and safety. Nanomaterials-based technologies arise as a promising tool to remove those contaminants from water. Nevertheless, interfacial water plays a major role in the adsorption of chemical compounds in the nanomaterials - as it plays in biological processes such as protein folding, enzyme activity, and drug delivery. To understand this role, in this study we employ Molecular Dynamics (MD) simulations to explore the adsorption dynamics of potassium diclofenac (K-DCF) on single-walled (SWCNT) and double-walled (DWCNT) carbon nanotubes, considering both dry and wet conditions. Our findings reveal that the structuring of water molecules around CNTs creates hydration layers that significantly influence the accessibility of active sites and the interaction strength between contaminants and adsorbents. Our analysis indicates higher energy barriers for adsorption in DWCNTs compared to SWCNTs, which is attributed to stronger water-surface interactions. This research highlights the importance of understanding nanoscale water behavior for optimizing the design and functionality of nanomaterials for water purification. These findings can guide the development of more efficient and selective nanomaterials, enhancing contaminant removal and ensuring safer water resources, while also contributing to a deeper understanding of fundamental biological interactions.