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

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.