Gemini Surfactant Modified Montmorillonite as Highly Efficient Adsorbent for Anionic Dyes

Abstract

The adsorption potential of a cheap, eco-friendly, and highly efficient adsorbent was studied as an alternative substitution of activated carbon for removal of organic anionic dyes from wastewater. The adsorbent (BDHP-Mt) prepared from the reaction of 1,3-bis(dodecyldimethylammonio)-2-hydroxypropane dichloride (BDHP) and Na-montmorillonite (Na-Mt) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), and thermogravimetry-derivative thermogravimetry (TG-DTG). Batch adsorption experiments were performed to remove anionic dyes such as Methyl orange (MO) and Congo red (CR) from aqueous solutions, using BDHP-Mt. The effects of pH and contact time under different temperatures on the adsorption capacities of MO and CR onto BDHP-Mt have been investigated. The results showed that the adsorption kinetics of MO and CR onto BDHP-Mt were in good agreement with pseudo-second-order model and the adsorption patterns of MO and CR could be well described by Langmuir isotherm. The comparative adsorption experiments indicated that BDHP-Mt exhibited much higher adsorption capacities (MO 239.11 mg g−1, CR 192.57 mg g−1) than active carbon (MO 203.88 mg g−1, CR 45.26 mg g−1), which may be due to the electrostatic interaction, partition adsorption and the bigger average pore diameter of BDHP-Mt. Thermodynamic experiments revealed that the two adsorption processes were spontaneous and endothermic. All the results implied that BDHP-Mt could be used as an alternative adsorbent of active carbon or other common adsorption materials for the adsorption of anionic dyes from effluents.