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@C18 sorbent allows the idea of entering the BTEX between the C18 (octadecyl) chains. This process resembles 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@C18 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@C18 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@C18 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.