Multifunctional absorbents for oily pollution control and mechanistic insights with theoretical simulation

Abstract

The fabrication of energy-efficient and high performing hydrophobic aerogels is highly desirable for addressing oil-based liquid pollution. The implementation of the aerogel adsorption process requires a comprehensive understanding of the macro-, micro-, and molecular-level mechanisms involved. To achieve this goal, molecular simulations can be employed to investigate the adsorption forces at the molecular level. Here, the cellulose extracted from Salvia miltiorrhiza Bunge residues (DS) were employed as natural building blocks to synthesize DS aerogel (DS-A) and subsequently silylated with methyltrimethoxysilane (MTMS). The resulting silylated DS aerogels (SDS-A) exhibited an exceptional adsorption capacity (25–105 g/g), endurable hydrophobicity, and a rapid oil adsorption rate of 5 s, with 2 wt% of DS cellulose (DS-C) and a porosity of 99.56%. Subsequently, the interactions were investigated between the silylated aerogel and oily liquids by means of docking, molecular dynamics (MD), and molecular mechanics-generalized Born surface area (MM-GBSA). Lipophilic energy and van der Waals energy surpassed Coulomb force in silylated cellulose/chlorobenzene complexes (−10.8 kcal/mol, −15.9 kcal/mol) and silylated cellulose/n-butyl acetate complexes (−4.3 kcal/mol, −17.1 kcal/mol). Molecular simulations revealed that van der Waals and hydrophobic interactions played crucial roles in adsorption. During the process, the adsorption mechanism was investigated at the molecular level, contributing to the understanding of silylated cellulose aerogel-based research. Moreover, the SDS-A demonstrated chemical durability with NaCl, NaOH, HCl, and oily liquids, as well as mechanical wear resistance without hydrophobic variation. Oil spill remediation results indicated that the aerogels could effectively facilitate continuous oil recycling from contaminated water in both artificial-driven and pump-driven experiments. This research provides novel insights into innovative solutions for oil-based liquid treatment technologies and future rational research.