A simple molecular simulation strategy for rapid prediction of BTEX sorption on a surface-modified sorbent

Abstract

Sorption of benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene (BTEX) molecules on Fe3O4@-SiO2@C-18 sorbent allows the idea of entering the BTEX between the C18 (octadecyl) chains. This process re-sembles BTEX+C18 mixing. Given the dominant effect of non-bond interactions, it should be possible to predict the sorption behavior using force field-based molecular simulations. Experimental data, i.e. sorption efficiency of Fe3O4@SiO2@C-18 towards BTEX in aqueous environment, were compared with results of two simulation strategies aimed at predicting sorption behavior using models significantly simplified compared to the real Fe3O4@SiO2@C-18 structure. The first strategy involved molecular dynamics performed on models containing only the shell with C18 chains in water with BTEX. The second strategy involved miscibility calculations (based on modified Flory-Huggins theory) performed on models containing only pairs of molecules: C18+BTEX and H2O+BTEX. Results of both simulation strategies are in good agreement with experimental data, i.e. BTEX sorption on Fe3O4@SiO2@C-18 can be studied using significantly simplified models. Given the speed of miscibility calculations and the simplicity of models used (pairs of molecules), the preparation of much larger models and time-consuming molecular dynamics simulations are not necessary. The sorption efficiency can be easily and quickly predicted by the miscibility calculations.