Adsorption Kinetics and Thermodynamics of Methyl Orange onto Surfactant-Modified Sepiolite

Organosepiolite has been prepared by exchanging with hexadecyltrimethylammonium bromide (CTAB) as a modifier. The adsorption kinetics and thermodynamics of methyl orange from aqueous solutions onto organosepiolite are studied, then the adsorption principle is discussed. The results of XRD and FTIR show that sepiolite can be well modified by treating with CTAB. The results indicate that the adsorption isotherm for methyl orange accords with the Langumir equation. The adsorption enthalpy and entropy changes are –13.54 kJ/mol and -32.8J/(mol•K), respectively. And the adsorption exhibits spontaneous physical adsorption and exothermic. The adsorption dynamics follows the laws of pseudo-second-order kinetics with the energy of activation is 6.36kJ/ mol.