Novel multi-hydroxyl containing organo-vermiculite for effective removal of 2-Naphthol: adsorption studies and model calculations

ABSTRACT

In this study, a multi-hydroxyl-containing gemini surfactant 1,4-bis(hexadecyldimethylammonio)-2,3-dihydroxylbutane dibromide (BHHB) is firstly introduced to modify vermiculite (Na-Vt) for 2-naphthol adsorption. Successful functionalization is verified from the enhanced hydrophobicity, increased organic carbon content, enlarged interlayer spacing and decreased surface area of BHHB-Vt over Na-Vt, constructing favorable structural microenvironments for 2-naphthol retention. Effective adsorptivity and excellent reusability are obtained from the comparison of BHHB-Vt (198.16 mg/g) over Na-Vt (43.26 mg/g C₀ = 300 mg/L, V = 30 mL, m = 0.03 g, t = 3 h). Partition process, hydrogen bond, OH-π interaction and electrostatic attraction are responsible for the adsorption, where OH-π interaction is stronger than hydrogen bond. The agreement of pseudo-second order and Langmuir models indicate a chemical adsorption feature on homogeneous surface. Notably, hydrogen groups connected at different carbon atoms exhibit less steric hindrance and wider molecule orbitals, providing stronger interactions between the adsorbent and targeted organic pollutant.

KEYWORDS:

• Multi-hydroxyl-containing gemini surfactant
• vermiculite
• adsorption
• 2-naphthol
• theoretical calculation

Acknowledgements

This research was funded by the National Natural Science Foundation of China (Nos.: 52062045 and 12047575), the Central Government Funds for Local Scientific and Technological Development (No.: XZ202101YD0019C), and the Central Government Funds for the Reform and Development of Local Colleges and Universities (No.: ZCKJ 2020-11).

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Funding

This work was supported by the National Natural Science Foundation of China [12047575,52062045]; Central Government Funds for Local Scientific and Technological Development [XZ202101YD0019C]; Central Government Funds for the Reform and Development of Local Colleges and Universities [ZCKJ 2020-11]; Everest Discipline Construction Project of Tibet University [ZF21000002].