Co-immobilization of 1-vinyl-3-octadecylimidazolium cations and p-styrenesulphonate anions on silica and their anti-interference performance for the adsorption of naphthols

Abstract

Adsorptive removals of naphthols are often interfered by some coexisting anions of aqueous solutions. In this work, 1-vinyl-3-octadecylimidazolium cations and p-styrenesulphonate anions were chemically co-modified on silica (denoted as Sil-PImC₁₈-SS) via the click chemistry reaction and were characterized. This material was created with the aim to explore the feasibility of removal of 1-naphthol (1-NAP) and 2-naphthol (2-NAP) from aqueous solutions. The prepared Sil-PImC₁₈-SS was used as an adsorbent to remove 1-NAP and 2-NAP from aqueous solutions and the effects of various variables for the adsorption of 1-NAP and 2-NAP were systematically studied. Among the coexisting anions tested, 0.2 mol L⁻¹ background NaCl or Na₂SO₄ aqueous solutions had no significant effect on the adsorption of 1-NAP and 2-NAP. The adsorption behaviors of 1-NAP and 2-NAP were well described by the pseudo-second order kinetic and the Dubinin–Radushkevich models with the maximum adsorption capacities of 84.4 mg g⁻¹ and 71.9 mg g⁻¹ for 1-naphthol and 2-naphthol, respectively. The adsorption was a spontaneous and exothermic process, and an adsorption mechanism was speculated to be the cooperative contributions from the hydrophobic interaction, hydrogen bonding interaction, and π–π stacking. Thus, Sil-PImC₁₈-SS can be potentially used as an effective adsorption material for naphthol pollutant removal from the water environment.