Synthesis and Surface Properties of Photoresponsive Gemini Surfactants: Implication for Remediating PAHs-Contaminated Groundwater

Yueming Han; Chaomeng Dai; Yanping Duan; Yaojen Tu; Shuguang Liu; Yalei Zhang

doi:10.1021/acsami.2c20623

Synthesis and Surface Properties of Photoresponsive Gemini Surfactants: Implication for Remediating PAHs-Contaminated Groundwater

ACS Appl Mater Interfaces. 2023 Mar 1;15(8):10642-10650. doi: 10.1021/acsami.2c20623. Epub 2023 Feb 15.

Authors

Yueming Han¹, Chaomeng Dai¹, Yanping Duan^{2

3

4}, Yaojen Tu², Shuguang Liu¹, Yalei Zhang⁵

Affiliations

¹ College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
² School of Environmental and Geographical Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, P. R. China.
³ Institute of Urban Studies, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China.
⁴ Yangtze River Delta Urban Wetland Ecosystem National Field Observation and Research Station, Shanghai 200234, P. R. China.
⁵ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.

PMID: 36790397
DOI: 10.1021/acsami.2c20623

Abstract

The efficient utility of surfactants remains a daunting task for groundwater remediation. In this study, we have synthesized a conventional photoresponsive surfactant 4-[4-[(4-butylphenyl)azo]phenoxy]butyldimethylethylammonium bromide (AzoPB) and a gemini photoresponsive surfactant N¹,N²-bis[4-[4-[(4-butylphenyl)azo]phenoxy]butyl]-N¹,N²-tetramethylethane-1,2-diammonium bromide (AzoPBT) for solubilizing PAHs in groundwater. The two surfactants' photosensitivity, surface properties, and solubilization/release ability for phenanthrene (Phe) and acenaphthylene (Ace) were studied in detail. Under UV-light irradiation for 15-20 s, the two surfactants can be converted from trans to cis, while cis-to-trans isomerization can be achieved under visible-light irradiation for 1 min. Compared to AzoPB, AzoPBT exhibited strong surface properties such as lower critical micelle concentration (0.52 mM), surface tension (γ, 28.94 mN·m^-1), minimum area (A_min, 1.72 × 10^-8 nm²), and higher maximum adsorption (Γ_max, 96.55 mol·m^-2). The solubility of Phe and Ace in the AzoPBT aqueous solution (12.84 and 14.27 mg/L) was much higher than that in the AzoPB aqueous solution (7.51 and 8.77 mg/L) and gradually increased as the surfactant concentration increased in both aqueous solutions. Compared to AzoPB, gemini surfactant AzoPBT exhibited stronger solubilization ability. After four cycles of cis-trans isomerization conversion, AzoPBT could still reduce the hydrophobicity of Phe in natural groundwater, although the solubility of Phe decreased slightly. Additionally, the release capacity of AzoPBT was significantly higher than that of AzoPB during the cyclic solubilization-release process. The results indicated that gemini photoresponsive surfactants should be preferable to conventional photoresponsive surfactants for groundwater remediation due to their higher solubilization and release efficiency for Phe in the cyclic solubilization and release process, which can improve repair efficiency, minimize secondary pollution, and reduce remediation costs.

Keywords: gemini surfactant; groundwater; photoresponsive surfactant; polycyclic aromatic hydrocarbons; surfactant-enhanced remediation.