Facile modification of homoionic-vermiculites by a gemini surfactant: Comparative adsorption exemplified by methyl orange

Abstract

A facile yet versatile modification method was adopted as template by functioning homoionic-vermiculites with 1, 2-bis (hexadecyldimethylammonio) ethane dibromide (16-2-16), which fulfilled the gap in the modification of vermiculite with gemini surfactant. The cation exchange capacity (CEC) values of the precursors were clearly determined by the improved BaCl2 measurement particular for vermiculite. The resultant organo-vermiculites (OVTs) were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM) and Thermogravimetric analysis (TG-DTG). Batch experiments were performed to evaluate the effects that metallization and organic modification have on the adsorption process of OVTs for a typical anionic dye, methyl orange (MO). The removal efficiencies of OVTs towards MO followed the order of OVT-Li>OVT-Na>OVT-K>OVT. Adsorption performances of OVTs were all susceptible to pH and contact time, with the adsorption processes reached equilibrium at 40–60min for OVT-Li, OVT-Na and OVT-K, while extended as long as 150min for OVT, which verified the necessity of metallization. The adsorption processes of OVTs towards MO were all fitted well with pseudo-second-order, Freundlich isotherm and endothermic processes in nature. Results obtained from this study would not only bring new lights into the high-efficiency and cost-effective adsorbent, especially OVT-Li and OVT-Na, but also provide theoretical guidance for the modification of vermiculite with gemini surfactant.