Removal of phenol from aqueous solutions by adsorption onto Mn–Ce–K solids

Oriana D’Alessandro,Horacio Thomas,Jorge E Sambeth

doi:10.1007/s11144-014-0747-6

Abstract

Mn–Ce solids were used for the adsorption of phenol from aqueous solution at 25 and 50 °C. The samples were prepared with a Mn–Ce molar ratio between 0 and 100 % by the alkaline co-precipitation method (KOH). Structural studies showed the formation of cryptomelane, Mn2O3, Mn5O8, Mn3O4 and CeO2. The formation of different phases is a function of the Ce concentration. The adsorption isotherms of phenol were determined and modelled with Langmuir and Freundlich equations. Sample 7/3 had a high adsorption capacity. Thermodynamic parameters, in flat and vertical position of phenol, were calculated. These parameters indicated that the adsorption of phenol onto Mn–Ce was spontaneous and exothermic. The DRIFTS study detected of both phenol and phenolate species adsorbed on the surface and the aromatic ring of phenol is parallel to the surface. The interaction between Mn and Ce enhanced the reducibility of the oxides and activated oxygen, which is favorable for the adsorption process.

Highlights

Phenolic compounds are used in different enterprises such as chemical, petroleum, paper, and petrochemical plants
The interaction between Mn and Ce enhanced the reducibility of the oxides and activated oxygen, which is favorable for the adsorption process
Several processes have been employed for the removal of phenolic compounds from aqueous solutions such as catalytic wet air oxidation, oxidation with ozone, electrochemical oxidation, photocatalytic degradation, adsorption and solvent extraction [1,2,3,4,5,6]

Summary

Introduction

Phenolic compounds are used in different enterprises such as chemical, petroleum, paper, and petrochemical plants. The adsorption of phenol is influenced by the properties of the solids (oxidation state, oxygen vacancies, hollow structure, etc.). For these reasons, new adsorbents such as MnO2, TiO2, and Fe2O3 have been reported. Many authors have studied the adsorption of organic compounds such as phenol, clarithromycin and catechol onto manganese oxides. Their results have shown that the oxidation states and the morphology are important factors in the adsorption process [7,8,9]

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