Diseño y caracterización de electrodos de pasta de carbono modificados con ciclodextrinas: aplicación en la determinación de metales pesados y determinación de sus complejos de inclusión

En este trabajo se presentan los resultados obtenidos de un tipo de modificación llevada a cabo sobre electrodos de pasta de carbono (CPE) preparados con aglomerante no conductor, que corresponde a la formación de un compuesto superficial producido por la oxidación-reducción cíclica de diferentes tipos de ciclodextrinas (CDs). A pesar de que no se presentan argumentos suficientes para establecer con claridad el tipo de compuesto formado sobre la superficie del electrodo, se presentan resultados experimentales discutidos sucintamente, que permiten establecer las propiedades de adsorción hacia los iones metálicos de plomo, mercurio y cadmio. Esta propiedad es utilizada para pre-concentrar estos iones sobre la superficie de los electrodos modificados, mejorando la señal de redisolución anódica del ion metálico previamente reducido. De esta manera es posible proponer un método de determinación de iones de metales pesados, con límites de detección y sensibilidad similares a los métodos que utilizan electrodos de gota colgante de mercurio (HMDE). Por lo tanto, el método propuesto en este trabajo de investigación presenta una alternativa menos contaminante para la detección de iones metálicos. Esta sería una de las aportaciones de este trabajo y la otra y más importante, es la de obtención de un electrodo modificado con un compuesto adherente y estable formado directamente con ciclodextrinas. La formación de nuevas especies químicas por la inclusión de los iones metálicos en las cavidades de las CDs, las cuales no habián sido reportados

Removal of Pb, Cu, Cd, and Zn Present in Aqueous Solution Using Coupled Electrocoagulation-Phytoremediation Treatment

Este estudio se evaluó un tratamiento acoplado de Electrocoagulación – Fitorremediación, con la finalidad de remover los metales pesados (Pb, Cu, Cd y Zn) presentes en agua residual minera y que esta agua pueda ser se reusóThis study presents the results of a coupled electrocoagulation-phytoremediation treatment for the reduction of copper, cadmium, lead, and zinc, present in aqueous solution. The electrocoagulation was carried out in a batch reactor using aluminum electrodes in parallel arrangement; the optimal conditions were current density of 8 mA/cm2 and operating time of 180 minutes. For phytoremediation the macrophytes, Typha latifolia L., were used during seven days of treatment. The results indicated that the coupled treatment reduced metal concentrations by 99.2% Cu, 81.3% Cd, and 99.4% Pb, while Zn increased due to the natural concentrations of the plant used. 1.Facultad de Química, UAEMe

Advanced Oxidation Processes: Ozonation and Fenton Processes Applied to the Removal of Pharmaceuticals

This chapter aims to present the fundamentals, important variables, and pharmaceuticals removed by ozonation and Fenton, which are only two of the current existing advanced oxidation processes. Some toxicological information regarding pharmaceuticals oxidized by ozonation is also included. Some strategies to improve such processes, like adding a catalyst, light, or electrical current, are also analyzed. Thus, this chapter intends to present general but fundamental aspects of the aforementioned processes

Use of recycled aluminum - polyethylene composite films as anodic electrodes for electrocoagulation of wastewater

artículo para uso de películas de aluminio polietilenoThis work evaluates the use of aluminum contained in the aluminum-polyethylene films as anodic electrodes using the electrocoagulation technique to reduce the pollutants contents of an industrial wastewater quickly and effectively. Two different current densities were applied 25 and 12.5 mA cm-2. When the current density of 25 mA cm-2 is used, the aluminum electrodes reduce the COD of wastewater by about 65% and the aluminum-polyethylene films electrodes reduces the COD by 56%. The color and turbidity reductions are 87 and 90% respectively. The use of aluminum-polyethylene films as electrodes in the electrocoagulation process contributes to the pollutant removal without the addition of chemical reagents or changing the pH, so it is both effective and environmentally friendly.Centro Conjunto de Investigación en Química Sustentable, UAEM-UNAM, CONACYT, UAEMe

Ozonation enhancement by Fe-Cu bimetallic particles

The aim of this work was to assess the effect of the bimetallic system Fe–Cu on the ozonation efficiency of indigo carmine and its main degradation product, isatin-5-sulfonic acid. As reference, experiments with single metal particles were also conducted. The metallic systems were synthesized by a chemical reduc- tion method and characterized by EPR and HR-SEM/EDS. Cu and Fe oxidation states were found to be 2 + . The ozonation process was carried out in an up-flow bubble column. The organic compounds concentra- tion was determined by UV–vis spectroscopy. The degree of oxidation and mineralization was determined by COD and TOC measurements, respectively. The effect of pH was also studied. It was found that the use of the bimetallic system not only considerably (by three times) improves the ozonation rate but also the mineralization degree of indigo carmine. The best results (97% indigo carmine removal and 92% of TOC removal) were obtained at pH 3 and with 10 0 0 mg/l of Fe/Cu particles.PRODEP 03.5/13/5257 y CONACY

REMOCIÓN DE CONTAMINANTES BIOREFRACTARIOS EN AGUAS RESIDUALES INDUSTRIALES MEDIANTE MÉTODOS ELECTROQUÍMICOS

El objetivo de este trabajo es investigar la efectividad del tratamiento electroquímico en la remoción de compuestos biorefractarios presentes en aguas residuales industriales. Se evaluó la remoción de compuestos orgánicos mediante el sistema de Electrocoagulación, utilizando electrodos de hierro, se determinaron las mejores condiciones de operación pH 8 y densidad de corriente de 45.45 Am-2, obteniendo una disminución en la demanda química de oxígeno (DQO) de 70%, 55% de DBO5, 81% de color, 80% de turbidez y 99% de coliformes totales.El objetivo de este trabajo es investigar la efectividad del tratamiento electroquímico en la remoción de compuestos biorefractarios presentes en aguas residuales industriales. Se evaluó la remoción de compuestos orgánicos mediante el sistema de Electrocoagulación, utilizando electrodos de hierro, se determinaron las mejores condiciones de operación pH 8 y densidad de corriente de 45.45 Am-2, obteniendo una disminución en la demanda química de oxígeno (DQO) de 70%, 55% de DBO5, 81% de color, 80% de turbidez y 99% de coliformes totales

Evaluación de la producción y aumento de la pureza de hidrógeno en el tratamiento electroquímico de aguas superficiales, empleando energía fotovoltaica

El presente trabajo muestra los resultados obtenidos de la producción simultánea de Hidrógeno y el tratamiento electroquímico de aguas superficiales. El volumen del reactor empleado fue de 2.5 L, el flujo de trabajo de 250 mL/min, y la duración de las pruebas fue de 5 horas. Se llevó a cabo el empleo de energías renovables, en este caso la energía fotovoltaica suministrada por un panel con una superficie aproximada de 1.00 m2 y un par de electrodos de Aluminio de formas cilíndricas y concéntricas. La pureza obtenida en el Hidrógeno fue del 94.6%, encontrándose como impureza principal al Oxígeno, a su vez los parámetros obtenidos en el agua tratada (DQO, Turbidez, pH y Conductividad) se encuentran dentro de los rangos establecidos por la normatividad mexicana.This paper presents the results of the simultaneous production of hydrogen and the electrochemical treatment of surface water. The reactor volume was used of 2.5 L, the workflow 250 mL / min, and the test duration was 5 hours. Conducted the use of renewable energies, in this case the power supplied by a photovoltaic panel with a surface area of 1.00 m2 and a pair of aluminum electrodes and concentric cylindrical shapes. The purity was obtained in 93% Hydrogen, Oxygen meeting as the main impurity, turn the parameters obtained in the treated water (COD, turbidity, pH and conductivity) are within the ranges established by Mexican standards

Fast reduction of Cr(VI) from aqueous solutions using alumina

artículo ya publicadoHexavalent chromium is challenging to remove from industrial wastewater due the solubility and anionic nature of the chromates. Cr(VI) is typically removed by reduction to Cr(III), then precipitation or adsorption, which requires multiple steps and bulk reagents and generates sludge. In this project, we have evaluated a sintered alumina disk as a single step sorbent for Cr(VI). The disk was porous enough that 20 mL samples passed through in about 3 s using light suction. A single pass through the disk only reduced the [Cr(VI)] by 10–20%, but by passing the solution through the disk five times up to 80% was removed in samples up to 130 mg/L and up to around 50% for much higher concentrations. The five passes through the filter disk took less than a minute. On each pass through the disk the characteristic chromate UV–vis absorbance decreased, the Cr(VI) concentration (by the diphenylcarbazide method) decreased, and the pH rose slightly. The XRD pattern showed no change in the crystal structure of the alumina, but the SEM/EDS identified chromium on the surface. In addition to confirming chromium on the surface of the alumina, the XPS spectra showed a change in the binding energy of the aluminum, which is consistent with complexation. The system was fast and effective (in series), so should be applicable to industrial wastewater treatment.UAEMex, CONACy

Modeling and scaling up of the Cr(VI) adsorption process by using mexicalcite natural mineral in a packed bed column

Artículo científicoThe natural mineral known as Mexicalcite is native to the southern region of Mexico, and due to its abundance and accessibility characteristics, as well as its insolubility in water, it is recommended as an adsorbent material. For such reasons, in this work Mexicalcite was used as adsorbent material to remove Cr(VI) in a packed bed column. The effects of the parameters: bed column height (Z), flow rate (Q), and the initial chromium concentration (C0), on the adsorption capacity (q) and removal percentage (%R) were evaluated. The results show minimal changes in adsorption capacity, specifically a 4% difference; with a mean value of 4.98 mg/g. However, maximum removal percentage was obtained for a high height in the bed column, where there is more contact time. However, low removal percentages were obtained for high flow rate, where the contact time is considerably less. The maximum removal was 94.09%, which was obtained with the highest packed bed height (Z= 6cm), initial concentration (C0= 25 mg/L), and lowest flow rate (Q= 2mL/min). The process was modeled using the Thomas, Adams-Bohart and Yoon-Nelson models. With the BDST model, it was possible to scale up the adsorption process and double the original column dimensions. In addition, the column dimensions were obtained theoretically, to operate continuously for 120 h. Finally, the chromium concentration at the outlet was 0.1 mg/L, using a value of 2 for the bed height/column diameter ratio (Z/d)