Graphene oxide and adsorption of chloroform: a density functional study

TL;DR

This study uses density functional theory to investigate how chloroform molecules adsorb onto graphene oxide, providing insights into its potential for filtering toxic chlorinated compounds from water.

Contribution

It presents the first atomic-scale calculations of chloroform adsorption on graphene oxide using vdW-DF-cx functional, highlighting its relevance for water filtration.

Findings

Adsorption energy ranges from 0.2 to 0.4 eV per molecule.

Adsorption energies are comparable to those on clean graphene.

Graphene oxide shows potential for filtering chlorinated hydrocarbons.

Abstract

Chlorinated hydrocarbon compounds are of environmental concerns, since they are toxic to humans and other mammals, are widespread, and exposure is hard to avoid. Understanding and improving methods to reduce the amount of the substances is important. We present an atomic-scale calculational study of the adsorption of chlorine-based substance chloroform (CHCl3) on graphene oxide, as a step in estimating the capacity of graphene oxide for filtering out such substances, e.g., from drinking water. The calculations are based on density functional theory (DFT), and the recently developed consistent-exchange functional for the van der Waals density-functional method (vdW-DF-cx) is employed. We obtain values of the chloroform adsorption energy varying from roughly 0.2 to 0.4 eV per molecule. This is comparable to previously found results for chloroform adsorbed directly on clean graphene, using similar calculations. In a wet environment, like filters for drinking water, the graphene will not stay clean and will likely oxidize, and thus adsorption onto graphene oxide, rather than clean graphene, is a more relevant process to study.