Computational investigations on the performance of transition metal carbide (MXene) for methylene blue dye adsorption and remediation from wastewater

Abstract

MXenes are receiving a lot of attention as adsorbents for environmental contaminants, due to their distinct characteristics, and the adsorption abilities were toughly influenced by the surface terminal groups. In this research the adsorption ability of free-standing Ti3C2 for methylene blue (MB) dye as a major hazardous contaminant in the watery environment is investigated and compared with the O and OH terminated MXene counterparts using computational material tools. DFT simulations are carried out to explore the structural properties and electronic structures, thermodynamic stability, and adsorption behavior of MB on the considered MXenes surface. The Ti3C2 monolayer is observed to behave as superior adsorbent for MB with strong interaction characteristic which is typical for the chemisorption followed by the Ti3C2(OH)2 and Ti3C2O2 MXenes with hydrogen bonding (strong physisorption) and electrostatics attractions, respectively. Meanwhile the DFTB-MD simulation of MB/MXene in ambient conditions reveals a strong ability of Ti3C2 monolayer in MB adsorption by chemical bond formation between N/C atom of MB and surface Ti atom followed by hydrogen bond formation in MB/Ti3C2(OH)2 system. The superior adsorption behavior of free-standing Ti3C2 monolayer in aqueous solution, make this novel monolayer a promising adsorbent for MB adsorption and removal from watery contaminants. The present findings will be beneficial for the design of suitable nanoadsorbents for remediation of hazardous organic contaminants from wastewater.