Nancy R. Sanabria

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

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.

Raschig Rings Based on Pillared Clays: Efficient Reusable Catalysts for Oxidation of Phenol

Abstract Extrudates of AlFe and AlCeFe pillared bentonites shaped as Raschig rings were used in the oxidation of phenol by a Fenton process, and the catalytic activity in terms of reuse was evaluated. All the tests of oxidation were carried out in a semibatch basket reactor, which operates under extremely mild reaction conditions (25 °C and atmospheric pressure). Extrudates of AlFe and AlCeFe pillared bentonites are reusable catalysts for the oxidation of phenol, reach 100% phenol conversion and between 36-42% selectivity towards CO2 after 8 h of reaction. In addition, Raschig rings showed efficient catalytic activity up to 10 consecutive uses and preserved structural and textural properties of the powdered active phases, even after reuse. The use of cerium as a promoter in the extruded material not only improved the catalytic activity but also increased the mechanical stability of extruded catalyst in the reaction medium.

Delaminated montmorillonite with iron(III)-TiO2 species as a photocatalyst for removal of a textile azo-dye from aqueous solution

ABSTRACT A set of mesoporous delaminated montmorillonites containing iron(III)-titanium oxide species was synthesized using two minerals: a bentonite as support and an ilmenite as source of Fe-TiO2 species. Several values of both sulphuric acid concentration and temperature were employed to extract Fe-TiO2 species from an ilmenite. Analyses by X-ray fluorescence, X-ray diffraction, scanning electron microscopy and nitrogen adsorption–desorption confirmed the successful formation of delaminated (or exfoliated) mesoporous structures. Optical properties of solids were determined by UV–Vis diffuse reflectance spectroscopy, and their band gap energy values were also calculated. A small UV-shift of band gap values regarding that of commercial photo-active TiO2 was detected as consequence of the quantum size effect, suggesting that photocatalytic experiments should be performed under UV-radiation assistance. The synthesized solids showed good activity in the photocatalytic oxidation of a textile dye (reactive yellow 145: RY 145), achieving conversions higher than 70% and chemical oxygen demand removal between 60% and 80%. GRAPHICAL ABSTRACT

Catalytic wet hydrogen peroxide oxidation of phenolic compounds in coffee wastewater using Al–Fe-pillared clay extrudates

AbstractThe effluents from the biological treatment of coffee wet processing wastewater (CWPW) contain non-biodegradable compounds, which are toxic to aquatic ecosystems. In this study, Al–Fe-pillared bentonite extrudates shaped into Raschig rings were used to catalyze the oxidation of the phenolic compounds in CWPW. The catalytic wet hydrogen peroxide oxidation was tested in a semi-batch basket reactor at 25 °C under atmospheric pressure. Al–Fe-pillared bentonite extrudates achieved a 62.4% total phenol conversion with a 67.5% selectivity toward CO2 after 96 h. Catalytic performance of the Al–Fe-pillared bentonite extrudates in the oxidation of phenolic compounds shows the potential of applying this catalyst for the treatment wastewaters. The implementation of systems for wastewater treatment is essential to the conservation of natural resources and the preservation of Colombian biodiversity, therefore, this research is a contribution to the sustainable development of coffee growing.

Propiedades Físicas del Jugo de Uchuva (Physalis peruviana) Clarificado en Función de la Concentración y la Temperatura

espanolSe estudio el efecto de la concentracion (20 a 50 °Brix) y la temperatura (20 a 50 °C) sobre la densidad y viscosidad del jugo de uchuva (Physalis peruviana) clarificado, empleando un diseno aleatorio con arreglo de dos factores: temperatura con cinco niveles, concentracion con siete niveles y tres repeticiones. Tambien se determino el punto de congelacion del jugo de uchuva en funcion de la concentracion. Los valores de densidad y viscosidad del jugo disminuyeron al aumentar temperatura y se incrementaron al aumentar la concentracion de solidos solubles. El efecto de la temperatura sobre la viscosidad del jugo a diferentes concentraciones fue descrito por una relacion tipo Arrhenius, encontrandose una energia de activacion de flujo en el rango de 7.02 a 17.62 kJ/mol. Los puntos de congelacion del jugo se calcularon a partir de las curvas de enfriamiento y los resultados se compararon con los estimados a partir de un modelo aplicable a jugos de frutas, con un error relativo promedio del 6.6%. EnglishThe effect of concentration (20 to 50 °Brix) and temperature (20 to 50 °C) on density and viscosity of clarified cape gooseberry (Physalis peruviana) juice was studied, using a randomized arrangement of two factors: temperature with five levels, concentration with seven levels and three repetitions. In addition, the freezing point of cape gooseberry juice at various concentrations was determined. Density and viscosity values of juice decreased with increasing temperature and increased with increasing concentration of soluble solids. The effect of temperature on viscosity at different concentrations of juice was described by an Arrhenius type relationship while the activation energy of flow was found to be in the range of 7.02 to 17.62 kJ/mol. The freezing points of juice at various concentrations were determined based on the cooling curves. The results were compared with those estimated from a model applicable to fruit juices, with an average relative error of 6.6%.

Catalytic oxidation with Al–Ce–Fe–PILC as a post-treatment system for coffee wet processing wastewater

The effluent from the anaerobic biological treatment of coffee wet processing wastewater (CWPW) contains a non-biodegradable compound that must be treated before it is discharged into a water source. In this paper, the wet hydrogen peroxide catalytic oxidation (WHPCO) process using Al-Ce-Fe-PILC catalysts was researched as a post-treatment system for CWPW and tested in a semi-batch reactor at atmospheric pressure and 25 °C. The Al-Ce-Fe-PILC achieved a high conversion rate of total phenolic compounds (70%) and mineralization to CO(2) (50%) after 5 h reaction time. The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 66%. The combination of the two treatment methods, biological (developed by Cenicafé) and catalytic oxidation with Al-Ce-Fe-PILC, achieved a 97% reduction of COD in CWPW. Therefore, the WHPCO using Al-Ce-Fe-PILC catalysts is a viable alternative for the post-treatment of coffee processing wastewater.