Microstructure-dependent CO2-responsive microemulsions for deep-cleaning of oil-contaminated soils

Lingfei Liu; Mingshan Zhang; Yi Lu; Gaojian Chen; Binda Lu; Lingling Ge; Zhouguang Lu; Dejun Sun; Zhenghe Xu

doi:10.1016/j.chemosphere.2023.140928

Microstructure-dependent CO₂-responsive microemulsions for deep-cleaning of oil-contaminated soils

Chemosphere. 2024 Feb:350:140928. doi: 10.1016/j.chemosphere.2023.140928. Epub 2023 Dec 11.

Authors

Lingfei Liu¹, Mingshan Zhang², Yi Lu³, Gaojian Chen⁴, Binda Lu¹, Lingling Ge⁴, Zhouguang Lu¹, Dejun Sun⁵, Zhenghe Xu⁶

Affiliations

¹ Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials, Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China; Key University Laboratory of Highly Efficient Utilization of Solar Energy and Sustainable Development of Guangdong, Southern University of Science and Technology, Shenzhen, 518055, China.
² School of Resources and Civil Engineering, Northeastern University, Shenyang, 110819, China.
³ Bioproducts Institute, Department of Chemical and Biological Engineering, Department of Chemistry and Department of Wood Science, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
⁴ School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225009, China.
⁵ Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong, 250100, China.
⁶ Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials, Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China; Key University Laboratory of Highly Efficient Utilization of Solar Energy and Sustainable Development of Guangdong, Southern University of Science and Technology, Shenzhen, 518055, China. Electronic address: xuzh@sustech.edu.cn.

PMID: 38092174
DOI: 10.1016/j.chemosphere.2023.140928

Abstract

CO₂-responsive microemulsion (ME) is considered a promising candidate for deep-cleaning and oil recovery from oil-contaminated soils. Understanding the responsive nature of different microstructures (i.e., oil-in-water (O/W), bicontinuous (B.C.) and water-in-oil (W/O)) is essential for unlocking the potential and mechanisms of CO₂-responsive emulsions in complex multiphase systems and providing comprehensive guidance for remediation of oil-contaminated soils. Herein, the responsiveness of microstructures of ME to CO₂ trigger was investigated using experimental designs and coarse-grained molecular dynamic simulations. MEs were formed for the first time by a weakly associated pseudo-Gemini surfactant of indigenous organic acids (naphthenic acids, NAs are a class of natural surface-active molecules in crude oil) and tetraethylenepentamine (TEPA) through fine tuning of co-solvent of dodecyl benzene sulfonic acid (DBSA) and butanol. The O/W ME exhibited an optimal CO₂-responsive character due to easier proton migration in the continuous aqueous phase and more pronounced dependence of configuration on deprotonated NA ions. Conversely, the ME with W/O microstructure exhibited a weak to none responsive characteristic, most likely attributed to its high viscosity and strong oil-NA interactions. The O/W ME also showed superior cleaning efficiency and oil recovery from oil-contaminated soils. The results from this study provide insights for the design of CO₂-responsive MEs with desired performance and guidance for choosing the favorable operating conditions in various industrial applications, such as oily solid waste treatment, enhanced oil recovery (EOR), and pipeline transportation. The insights from this work allow more efficient and tailored design of switchable MEs for manufacturing advanced responsive materials in various industrial sectors and formulation of household products.

Keywords: Naphthenic acid; Oil-water phase separation; Oily solid waste treatment; Pseudo-gemini surfactant; Switchable emulsion.

MeSH terms

Carbon Dioxide*
Emulsions / chemistry
Oils* / chemistry
Soil
Surface-Active Agents / chemistry
Water / chemistry

Substances

Carbon Dioxide
Oils
Surface-Active Agents
Emulsions
Water
Soil