Phenol Adsorption Characteristics of Two Novel Gemini Surfactants Modified Organ-bentonites

Abstract

Bentonite was modified by means of ion exchange with two Gemini surfactants(1, 3- bis(dodecyldimethylammonio)-propane dibromide(BDP) and 1, 3-bis(dodecyldimethylammonio)-2-hydroxypropane dichloride(BDHP)) respectively to prepare two organ- bentonites BDP-B and BDHP-Bt. The organ-bentonites were characterized by X-ray diffraction(XRD) and FT-IR spectroscopy. Then their adsorption ability of phenol from aqueous solutions was examined in terms of the p H value and contact time.The results show that the adsorption of phenol increases with of the increasing p H value. The adsorption kinetics was found to follow the pseudo- second- order kinetic model and the equilibrium data fitted the Langmuir and Temkin equations better than Freundlich equation for both BDP modified bentonite(BDPBt) and BDHP modified bentonite(BDHP-Bt). The results also show that BDHP-Bt containing one hydroxyl in the Gemini surfactant molecule was more effective than BDP-Bt for the sorption of phenol from aqueous solutions. Thus, a new idea was put forward for the selection of high efficient modified agent, i.e., hydroxyl-containing Gemini surfactants. The negative values of ΔG° and ΔH° obtained from thermodynamic study of adsorption process indicated the spontaneous and exothermic nature for the two organ- bentonites.