Author: ESMERALDA VENCES ALVAREZ

Modificación de carbón activado con La(III) para la remoción de fluoruros del agua

ESMERALDA VENCES ALVAREZ (2014)

"El flúor es benéfico para la salud a niveles de 0.7 mg/L, pero se considera peligroso cuando es ingerido a concentraciones superiores a 1.5 mg/L, que es el límite recomendado por la Organización Mundial de la Salud (OMS). La contaminación por fluoruros del agua es un problema que se encuentra presente a nivel mundial. El objetivo de esta investigación fue evaluar la viabilidad del carbón activado (CAG) modificado con lantano para la eliminación de fluoruro a partir de soluciones acuosas. Se realizó la caracterización del material mediante FT-IR, XRD, SEM, distribución de pKa¿s y punto de carga cero (PCC) con la finalidad de elucidar el posible mecanismo de anclaje del lantano sobre la superficie del carbón activado y el mecanismo de adsorción de fluoruros en el carbón modificado. Se realizaron experimentos de adsorción en batch para estudiar el efecto de pH, presencia de aniones co-existentes, presencia de materia orgánica y la capacidad máxima de adsorción en solución acuosa. Los resultados muestran que el lantano tiene preferencia por unirse a los grupos carboxilos y fenólicos. La titulación potenciométrica muestra que el carbón modificado (CAG-La) tiene una carga positiva a pH menores a 8. La capacidad de adsorción del CAG-La aumenta 5 veces con respecto al CAG sin modificar a una concentración inicial de F- de 20 mg/L. La presencia de aniones co-existentes no tiene ningún efecto en la capacidad de adsorción del fluoruro a concentraciones menores de 30 mg/L. Los experimentos de adsorción mostraron una alta afinidad del F- por el material adsorbente (CAG-La)."

"Fluoride is beneficial to humans health at levels of 0.7 mg L-1, but is considered dangerous when ingested at higher concentrations to 1.5 mg L-1, which is the limit recommended by the World Health Organization (WHO). The consumption of water with high fluoride levels for prolonged periods of time represents a health risk. The water contamination by fluoride is a problem that is present worldwide. In Mexico, the water fluoride concentration in the states of Aguascalientes, Durango, Guanajuato, Jalisco, Zacatecas and San Luis Potosi is above the maximum limit established by the NOM -127- SSA1- 1994. The literature reports the removal of fluoride by using lanthanum oxide, and modified activated carbon with aluminum, manganese or zirconium oxides. Some authors have reported that lanthanum oxides have a high adsorption capacity for fluorides, however, no reports have been found about the use of anchored lanthanum oxides on activated carbon for application in water treatment. The objective of this research was to evaluate the feasibility of activated carbon (GAC) modified with lanthanum oxides for defluoridation of aqueous solutions. Materials characterization was performed by FT-IR, XRD, SEM, pKa's distribution, and point of zero charge (PZC) in order to elucidate the possible mechanism of the lanthanum anchorage on the surface of activated carbon and the fluoride adsorption mechanism on the modified carbon. Adsorption experiments were conducted in batch and the effects of pH, presence of co-existing anions and organic matter were studied. The results showed that lanthanum prefers binding to the carboxyl and phenolic groups. Potentiometric titrations revealed that the modified carbon (GAC-La) has a positive charge at pH lower than 8. The adsorption capacity of the modified GAC increased five times in comparison to unmodified GAC, at an initial concentration of F- of 20 mg L-1. The presence of co-existing anions has not effect on the adsorption capacity of fluoride at concentrations below of 30 mg L-1. Adsorption experiments indicated high affinity of F- by the modified adsorbent material (GAG-La)."

Master thesis

Fluoruro Adsorción Lantano Carbón activado INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS INGENIERÍA Y TECNOLOGÍA QUÍMICAS INGENIERÍA Y TECNOLOGÍA QUÍMICAS

Inmovilización de oxihidróxidos de lantano sobre carbón activado para incrementar su capacidad de remoción de fluoruros del agua

Anchorage of lanthanum oxyhydroxides on activated carbon to increase its fluoride removal from water

ESMERALDA VENCES ALVAREZ JOSE RENE RANGEL MENDEZ (2017)

"El flúor es beneficioso para la salud humana a una concentración de 0.7 mg L-1, pero se considera peligroso cuando es ingerido a concentraciones superiores a 1.5 mg L-1, el cual es el límite recomendado por la Organización Mundial de la Salud (OMS). La contaminación del agua por fluoruros es un problema que se encuentra presente a nivel mundial. Por lo tanto, se requiere invertir en el desarrollo de nuevos materiales y tecnología más eficientes para la remoción de contaminantes prioritarios. El objetivo de esta investigación fue anclar óxidos de lantano sobre un carbón activado granular (CAG) comercial para remover fluoruros presentes en el agua. El CAG modificado con lantano se caracterizó mediante FT-IR, XRD, SEM, distribución de pKa´s y punto de carga cero (PCC) con la finalidad de elucidar el posible mecanismo de anclaje del lantano sobre la superficie del carbón activado y el mecanismo de adsorción de fluoruros en el carbón modificado. realizaron experimentos de adsorción en batch para estudiar el efecto del pH, de la presencia de aniones co-existentes, y la capacidad máxima de adsorción en solución acuosa. Los resultados mostraron que la capacidad de adsorción del carbón modificado con lantano (CAG-La) aumentó 5 veces con respecto al CAG comercial a una concentración inicial de F- de 20 mg L-1, a pH 7 y 25 °C. La presencia de aniones co-existentes no tiene ningún efecto en la capacidad de adsorción del fluoruro a concentraciones menores de 30 mg L-1."

"Fluoride is beneficial to humans health at a concentration of 0.7 mg L-1, but it is considered dangerous when ingested at concentrations above 1.5 mg L-1, which is the limit concentration recommended by the World Health Organization (WHO). Water pollution by fluorides occurs in many places around the world. Therefore, more efficient materials and technology are required to overcome this environmental problem. The objective of this research was to anchor lanthanum oxides on a commercial granular activated carbon (GAC) to remove fluorides from water. The modified GAC was characterized by FT-IR, XRD, SEM, pKa’s distribution, and point of zero charge (PZC) in order to suggest how lanthanum anchors on the activated carbon surface and also to propose the fluoride adsorption mechanism on the modified carbon. Adsorption experiments were carried out in batch to study the effect of pH, presence of co-existing anions, and the maximum adsorption capacity in aqueous solution. These results showed that the adsorption capacity of the modified carbon (GAC-La) increased 5 times compared to the commercial GAC at an initial concentration of 20 mg L-1 of F- at pH 7 and 25° C. Finally, the presence of co-existing anions has no effect on the fluoride adsorption capacity at concentrations below 30 mg L-1."

Article

INGENIERÍA Y TECNOLOGÍA

Adsorbentes híbridos oxihidróxidos metálicos-carbón para remover contaminantes prioritarios del agua: fluoruro y arsénico

Metal oxyhydroxides-carbon hybrid adsorbents to remove priority pollutants from water: fluoride and arsenic

JOSE RENE RANGEL MENDEZ ESMERALDA VENCES ALVAREZ JAVIER ANTONIO ARCIBAR OROZCO LITZA HALLA VELAZQUEZ JIMENEZ (2015)

"La contaminación del agua por fluoruros (F- ) y arsénico (As) es un problema de importancia mundial, ya que el agua subterránea de varios países excede los límites permisibles establecidos por la Organización Mundial de la Salud (OMS), lo cual representa un riesgo para la salud humana. Por esta razón, el F- y el As se consideran contaminantes prioritarios que determinan la calidad del agua. Para eliminar o reducir la concentración de estos contaminantes se han implementado diversos procesos, tales como: intercambio iónico, precipitación-coagulación, electrodiálisis, nanofiltración, ósmosis inversa, y diálisis Donnan; sin embargo, la mayoría de estos métodos a menudo implican costos de operación elevados y mantenimiento continuo. El uso de adsorbentes diseñados específicamente para eliminar estos elementos representa una alternativa con gran potencial para ser aplicados a corto plazo en sistemas de tratamiento de agua. Una opción atractiva para mitigar la contaminación del agua por F- y As es el uso de carbón activado (CA) como material adsorbente. Sin embargo, este material tiene algunas limitaciones relacionadas con su capacidad y selectividad que deben ser superadas. La modificación de carbón activado con partículas de oxihidróxidos metálicos de tamaño nanométrico tiene el potencial de eliminar selectivamente estos contaminantes, sin embargo, el mayor reto es el anclaje de estos metales en la superficie del CA. Nuestro grupo de investigación ha contribuido en los últimos años a esta área de investigación mediante la síntesis de adsorbentes híbridos basados en oxihidróxidos metálicos-carbón con capacidad de adsorción elevada. Lo anterior considerando la relación entre el área específica, distribución de carga, grupos funcionales, contenido de metal y la capacidad de adsorción."

"Water polluted with fluoride (F- ) and arsenic (As) is a problem of global relevance. The groundwater of several countries exceeds the allowable concentration limits for these compounds as recommended by the World Health Organization (WHO), thus posing a serious human health risk. For this reason, F- and As are considered priority pollutants that determine water quality. To eliminate or reduce the concentration of these contaminants, several processes have been implemented such as: ion exchange, precipitation– coagulation, electrodialysis, nano-filtration, reverse osmosis, and Donnan dialysis. However, most of these methods often involve high operating and maintenance costs. The use of adsorbents that are specifically designed for the removal of these elements represent a viable alternative for future water treatments system. An attractive option is the use of activated carbon (AC) as an adsorbent material. Nevertheless, limitations related to its capacity and selectivity must be overcome. The modification of the activated carbons surface with metal oxyhydroxides nanoparticles has the potential to selectively remove these contaminants. The biggest challenge is controlling the anchorage of the oxyhydroxide nanoparticles on the AC surface. Our research group has contributed in recent years to this research area by synthesizing hybrid adsorbents based on metal oxyhydroxides nanoparticles-AC with elevated adsorption capacities and chemical stability, this considering the relationship among surface area, charge distribution, functional groups, metal content, and contaminant uptake."

Article

INGENIERÍA Y TECNOLOGÍA

Water defluoridation with special emphasis on adsorbents-containing metal oxides and/or hydroxides: A review

Litza Halla Velázquez Jiménez ESMERALDA VENCES ALVAREZ JOSE LUIS FLORES ARCINIEGA Horacio Flores Zúñiga JOSE RENE RANGEL MENDEZ (2015)

"Fluoride contamination in drinking water has been recognized as one of the major worldwide problems since this represents a serious threat to human health. The World Health Organization (WHO) recommends the guideline value (maximum permissible limit) of 1.5 mg L?1 for fluoride in drinking water. Unfortunately, many countries have high fluoride concentrations (up to 30 mg L?1) in water supplies that may cause widespread fluorosis and skeletal illnesses among the population. Many methods have been developed for fluoride removal from water including adsorption, ion exchange, electrodialysis and precipitation. Nevertheless, more efficient and cost-effective processes and materials are needed to comply with the fluoride maximum permissible limit. Adsorption has been widely used because it is the most cost-effective methodology for the removal of ionic contaminants from aqueous solutions. Various adsorbent materials have been used to remove fluoride from water, for instance activated alumina, activated carbon, bone char, minerals, among others, but unfortunately their chemical stability and/or selectivity and adsorption capacity is something that still has to improve substantially. During the last decade, metal oxyhydroxides in powder form and supported on different matrixes have been of great interest for fluoride removal. This review condenses the advances on this last topic that is still under study."

Article

Fluoride Adsorption Metal oxyhydroxides Water treatment BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Gold recovery from very dilute solutions from a mine in closing process: adsorption-desorption onto carbon materials

ESMERALDA VENCES ALVAREZ ELIAS RAZO FLORES Isabel Lázaro ROBERTO BRIONES GALLARDO GUILLERMO VELASCO MARTINEZ JOSE RENE RANGEL MENDEZ (2017)

"The aurocyanide complex recovery by precipitation with zinc decreases when gold concentration drops to < 20 μg L− 1. Therefore, a technology capable of recovering gold from very diluted solution is necessary. Adsorption and desorption experiments were carried out with real solutions in batch and in continuous processes to determine the gold adsorption capacity and rate onto two activated carbons (AC). The results showed that AC F400 and CSC removed 86 and 81 μg g− 1, respectively, at pH 11 and Ce of 10 μg L− 1 in about 4 h. Whereas desorption test by NaOH and CN− showed a gold recovery of up to 86%. These experiments were correlated to the textural and chemical properties of adsorbents and to the chemical composition of samples from a heap leach process. AC is a highly efficient and selective adsorbent for gold cyanide solutions when gold is present in very low concentration (< 12 μg L− 1)."

Article

Gold cyanide Activate carbons Adsorption Desorption Packed bed column BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA FÍSICA

An overview of reclaimed wastewater reuse in gold heap leaching

Rodolfo Palomo Briones MONSERRAT OVANDO FRANCO Elías Razo Flores María de Lourdes Berenice Celis García JOSE RENE RANGEL MENDEZ ESMERALDA VENCES ALVAREZ ROEL CRUZ GAONA Isabel Lazaro ROBERTO BRIONES GALLARDO (2016)

"The intensive use of groundwater by the gold mining industry is an important sustainability concern, especially in arid and semiarid regions where groundwater is a scarce resource. Alternatives, such as water reuse, treatment and recycling, have been implemented to overcome this issue. The potential use of reclaimed wastewater in gold heap leaching, without decreasing the process efficiency, has not yet been considered. Hence, this review focuses on the physicochemical, biological, and chemical features (organic matter, microbial loads, metal ions, and anions) of reclaimed wastewater that may limit its use in gold heap leaching."

Article

Cyanide biodegradation Gold Heap leaching Reclaimed wastewater Sustainable mining INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA METALÚRGICA TECNOLOGÍA METALÚRGICA