Properties of adsorption of methyl orange onto intercalated CTMA-Bentonite

The paper prepares the intercalated CTMA-bentonite by Na-bentonite cation exchanged with cetyltrimethylammonium and characterizes the product by XRD and IR techniques. The d_ 001 spacing value of CTMA-bentonite is 7.54 larger than that of Na-bentonite at 100% of the cation exchange capacity. The IR spectrum shows that the intensities of OH stretching and bending vibrations of CTMA-bentonite decrease greatly compared with the untreated Na-bentonite. Batch experiments are carried out at 303 K, 323 K and 343 K to obtain the sorption isotherms of methyl orange on CTMA-bentonite. The results show that the sorption isothermal data can be well described by Langmuir and Freundlich model accurately. The dynamical data fit well with pseudo-second-order kinetic model. Thermodynamic parameters such as changes in the free energy (ΔG0), the enthalpy (ΔH0) and the entropy (ΔS0) are also evaluated. The overall adsorption process of methyl orange on CTMA-bentonite is spontaneous, exothermic physisorption. The CTMA-bentonite can be employed as low-cost alternatives to activated carbon in wastewater treatment for the removal of corlor which comes from textile dyes.