Application of molecular docking in sorption of hydrophobic organic contaminants on black carbon

Abstract

This study explored the mechanism and environmental significance of hydrophobic organic contaminants (HOCs) sorption by black carbon samples (BCs) using a newly developed molecular structure establishment method and the latest molecular docking technology. BCs of different evolution stages were prepared based on low maturity kerogen. Total of 70 types of HOCs molecules were selected, including alkanes, cycloalkanes, polycyclic aromatic hydrocarbons, and their derivatives, as ligands to perform docking studies using five different BCs molecular models. Based on the Gibbs free energy distribution between HOCs and BCs obtained by docking calculation, the capacity of sorption was deduced. The results showed that the molecular weight, methyl content, and condensation degree are the three main factors affecting the sorption ability of HOCs on BCs, and aromatic compounds have remarkable advantages in sorption, following the order of aromatic compounds > cycloalkanes > alkanes. It is worth noting that in order to ensure the correctness of molecular docking technology in the inference of adsorption capacity, we carried out the adsorption experiments of BCS with eight organic reagents. The experimental results are highly consistent with the calculated results, which not only proves the feasibility of this technology, but also shows that the intermolecular force represented by Gibbs free energy is closely related to the capacity of sorption. This study establishes a novel approach to elucidate contaminant-macromolecule interactions, enabling prediction of HOCs environmental behavior and evaluation of BCs' sequestration potential. The method enhances experimental efficiency for multiphase pollutant sorption studies, proving particularly advantageous for preliminary screening. Importantly, it allows safe investigation of toxic/volatile compounds while ensuring researcher safety.