Efficient preparation and molecular dynamic (MD) simulations of Gemini surfactant modified layered montmorillonite to potentially remove emerging organic contaminants from wastewater

A novel Gemini surfactant, Propyl bis (hexadecyl dimethyl ammonium) chloride (16-3-16), was utilized to modify Ca-montmorillonite (Ca-Mt) to obtain organo-montmorillonite (G-Mt). The structure and morphology of G-Mt were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS), Thermogravimetric analysis (TGA), N-2 adsorption/desorption isotherms (BET) and Zeta potential. G-Mt was used to adsorb a class of emerging contaminants (ECS) such as 1-Hydroxybenzotriazole (HOBT), 1H-Benzotriazole (BTA) and 5-Methyl-1H-benzotriazole (TEA) from wastewater. Molecular dynamic (MD) simulations were performed to reveal the arrangement of 16-3-16 in the interlayer gallery of Ca-Mt. Furthermore, the adsorption properties of G-Mt were observed under different experimental conditions. The results showed that the saturation loading of 16-3-16 on Ca-Mt was 1.0 CEC and the maximum adsorption capacities at equilibrium were 25.93 mg/g, 18.31 mg/g and 16.24 mg/g for HOBT, BTA, and TTA, respectively. However, the adsorption capacities of three contaminants on Ca-Mt were only 2.37 mg/g, 1.28 mg/g, and 1.06 mg/g. The optimum removal of HOST, BTA and TTA occurred at pH 4, 9, 9 respectively. The adsorption processes of three contaminants fitted well with the Langmuir isotherm model and the pseudo-second-order model. Thermodynamic results indicated that the adsorption processes of HOBT, BTA, and TTA on G-Mt were spontaneous and endothermic. These researches are expected to provide a sixpenny and efficient method to treat emerging contaminants in wastewater.