Methane adsorption in an SDS–oil–cellulose compound system: an experimental and interface simulation study

Abstract

Methane leakage presents serious environmental hazards and explosion risks, while conventional mitigation methods such as gas venting remain inefficient and environmentally unfriendly. This study presents a novel oil–water composite adsorbent system that leverages the synergistic effects of cellulose acetate propionate (CAP), plant oils, and surfactants to enhance methane adsorption efficiency. Characterization experiments and molecular dynamics simulations were conducted to investigate the interfacial properties and the mechanisms by which CAP influences interactions and adsorption capacity. Adsorption and spraying experiments were carried out to investigate the effects of different plant oils (castor, olive, linseed), surfactant-to-oil mass ratios, and CAP presence on methane adsorption capacity. Results showed a highest adsorption efficiency of 14.36% was achieved at a surfactant-to-castor oil ratio of 7.5 : 1 in the solution containing CAP. CAP addition increased micelle size and improved methane adsorption. However, in spraying tests, CAP did not significantly enhance methane adsorption capacity. The highest methane adsorption concentration of 6.73% vol. was achieved at a surfactant-to-castor oil ratio of 7.5 : 1. Molecular dynamics simulations revealed that CAP substantially lowered interfacial tension and reduced the free energy barrier for methane diffusion. The distribution coefficient of methane in the CAP-containing system was 2.67 log units, indicating a stronger affinity for methane. Radial distribution function analysis revealed that the nitrogen-containing groups in CAP enhance interfacial interactions, thereby improving the aggregation patterns of the oil–surfactant system, facilitating methane transport within the oil–water system. These integrated experimental and computational findings provide new insights into designing efficient methane adsorbents and offer theoretical guidance for their practical application.