Development of Pillared Clays for Wet Hydrogen Peroxide Oxidation of Phenol and Its Application in the Posttreatment of Coffee Wastewater

Nancy R. Sanabria,Rafael Molina,Sonia Moreno

doi:10.1155/2012/864104

Nancy R. Sanabria, Rafael Molina + Show 1 more

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https://doi.org/10.1155/2012/864104

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Abstract

This paper focuses on the use of pillared clays as catalysts for the Fenton-like advanced oxidation, specifically wet hydrogen peroxide catalytic oxidation (WHPCO). This paper discusses the limitations on the application of a homogeneous Fenton system, development of solid catalysts for the oxidation of phenol, advances in the synthesis of pillared clays, and their potential application as catalysts for phenol oxidation. Finally, it analyzes the use of pillared clays as heterogeneous Fenton-like catalysts for a real wastewater treatment, emphasizing the oxidation of phenolic compounds present in coffee wastewater. Typically, the wet hydrogen peroxide catalytic oxidation in a real effluent system is used as pretreatment, prior to biological treatment. In the specific case of coffee wet processing wastewater, catalytic oxidation with pillared bentonite with Al-Fe is performed to supplement the biological treatment, that is, as a posttreatment system. According to the results of catalytic activity of pillared bentonite with Al-Fe for oxidation of coffee processing wastewater (56% phenolic compounds conversion, 40% selectivity towards CO2, and high stability of active phase), catalytic wet hydrogen peroxide oxidation emerges as a viable alternative for management of this type of effluent.

Highlights

IntroductionTo expand the pillaring process to an industrial scale, it was necessary to simplify procedures and optimization of the unit operations involved, to decrease the volume of water and synthesis times
The results showed that the coffee wet processing wastewater (CWPW) contains mainly chlorogenic and hydroxycinnamic acids: 3-O-p-coumaroylquinic acid (3pCoQA), 4-O-p-coumaroylquinic acid (4-pCoQA), and 5O-p-coumaroylquinic acid (5-pCoQA), and caffeic and ferulic acids
The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 60%

Summary

Introduction

To expand the pillaring process to an industrial scale, it was necessary to simplify procedures and optimization of the unit operations involved, to decrease the volume of water and synthesis times In this regard, Perez et al used ultrasound for aging and intercalating of pillared bentonite with Al-Ce and Al-Ce-Fe. The use of ultrasound showed a clear effect in the synthesis of this type of solids allowing the synthesis in a shorter time and preserving the physicalchemical characteristics as well as catalytic activity in the oxidation reactions [51]. The properties of AlCu-PILC were compared with those of analogous iron-based clays (AlFe-PILC) in the wet hydrogen peroxide catalytic oxidation of model phenolic compounds These two catalysts have comparable performances in all these reactions, they showed some differences in the rates of the various steps of the reaction. This result proved the importance of cerium in the synthesis of pillared clays with mixed systems because it increased the catalytic activity due to its oxygen storage capacity, and increased the mechanical stability of extruded catalysts in the reaction medium [27]

Fenton Oxidation with Pillared Clays for Wastewater Treatment

Environmental Problems Associated with Coffee Wet Processing in Colombia

Findings

Conclusions