Removal of Dyes through Polymeric Membrane for Water Purification: A Computational Approach

Abstract

The discharge of toxic basic dyes into water bodies is a critical environmental challenge that pose severe risks to both human health and aquatic ecosystems. This study investigates the removal of these synthetic basic dyes from wastewater using carboxylated polypropylene membrane employing integrated computational techniques such as Quantitative Structure Activity Relationship (QSAR) modelling, Monte Carlo (MC) and Molecular Dynamics (MD) studies. The study focuses on designing and optimizing polymeric membranes for dye removal by examining the adsorption mechanism at the molecular level. Firstly, QSAR modelling was performed by using WS module of Estimation Program Interface Suite (EPI-Suite) v4.11 screening tool for calculating water solubility of five basic dyes in water. The Forcite module of Materials Studio 2020 software was used to optimize the geometries of dyes and membrane with COMPASS forcefield with fine quality. These optimized structures were utilized in the adsorption studies of these basic dyes on carboxylated-polypropylene membrane (carboxylated-PP). To calculate adsorption energies and to obtain the most stable adsorption complexes, Monte Carlo (MC) simulations were carried out through Adsorption Locator Tool (ALT) of Materials Studio 2020. The MC searches were performed for 100 cycles each containing 1500 steps with COMPASS forcefield, and fine quality. Furthermore, to get deeper insights into the adsorption process and to analyze the time-dependent behavior of the dye-polymer system, Molecular Dynamics (MD) studies were performed for 10ns with time-step of 1fs and COMPASS forcefield using Forcite module. The NPT ensemble was used with temperature and pressure set as 298K and 0.0001 GPa, respectively. Nose and Berendsen methods were selected for temperature and pressure control. The findings revealed the promising potential of carboxylated-PP in the effective removal of all dyes, however, the highest adsorptive removal efficiency of Basic Green-4 (BG-4) with highest most negative value -26.5141 kcal/mol.