Synthesis and characterization of an inorganic/organic-modified bentonite and its application in methyl orange water treatment

Abstract

The adsorption of methyl orange (MO) onto hydroxyl-aluminum and cetyltrimethyl ammonium bromide (CTAB)-modified bentonite (Al/CTAB-bent) was studied. The effects of contact time, Al/CTAB-bent dosage, temperature, initial pH and an initial MO concentration on MO adsorption were investigated. The surface properties and structure of Al/CTAB-bent were measured by some techniques, such as X-ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, energy dispersive X-ray spectroscopy and Fourier transform infrared spectrometry. The color and chemical oxygen demand removal efficiency can reach up to 99% and 97%, respectively. The adsorption kinetics and isotherm of MO onto Al/CTAB-bent were also investigated. The results revealed that Langmuir model was more suitable to describe MO adsorption than Freundlich model. The adsorption kinetics follows the pseudo-second-order kinetics model better. The thermodynamic parameters such as ΔG₀, ΔH₀, and ΔS₀ were also evaluated.

Keywords:

• Bentonite
• Al/CTAB-bent
• Methyl orange
• Adsorption isotherm
• Adsorption kinetics

Acknowledgments

The authors are grateful to be supported by the Fundamental Research Funds for the Central Universities (GK201302013) and open fund (OGL201202) of State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.