Author: CARLOS EDUARDO BARRERA DIAZ

Remoción de cromo hexavalente, presente en aguas residuales industriales por métodos electroquímicos

CARLOS EDUARDO BARRERA DIAZ (2003)

126 páginas. Doctorado en Ciencias e Ingeniería Ambientales.

En esta investigación se estudia la reducción de Cr(VI) por medio de técnicas electroquímicas, para cumplir con los límites máximos permisibles señalados en la normatividad ambiental. Se realizaron pruebas experimentales con distintos tipos de reactores electroquímicos que emplean electrodos de acero al carbono. Se identificaron tres variables pH, densidad de corriente y régimen de flujo, que afectan de manera decisiva el proceso de reducción de Cr(VI). Asimismo, se realiza un estudio termoquímico de los sistemas Cr(VI)-Cr(III)-H2O-e- y Fe(III)-Fe(II)-H2O-e-, lo cual permite optimizar las condiciones a las cuales la remoción de cromo se lleva a cabo. Con la finalidad de identificar las ventajas que ofrece el uso de la técnica electroquímica sobre los métodos clásicos de reducción química, se compararon dos métodos para remover el Cr(VI) de aguas residuales industriales. Estos métodos se basan en la siguiente reacción de reducción: 3Fe (II) (ac) + Cr (VI ) (ac) ↔ 3Fe (III) (ac) + Cr (III) (ac), Sin embargo la forma en que se añade el ion ferroso es diferente. Cuando se utiliza un método químico se agrega FeSO4⋅7(H2O)(s), mientras que cuando se emplea el método electroquímico el hierro se disuelve del ánodo. Una vez que ocurre el proceso de reducción, se modifica el pH de la solución acuosa con una solución 1M de hidróxido de calcio, para que los iones Cr(III)(ac) y Fe(III)(ac) precipiten. Los resultados experimentales muestran que usando ambos métodos de tratamiento es posible alcanzar una eficiencia de reducción de Cr(VI) del 99.5 %. Sin embargo, el método electroquímico, además de tener un mejor control de proceso, genera una cantidad significativamente menor de lodos residuales (60 %) en comparación con el método químico. Finalmente se propone un modelo matemático para realizar una simulación del proceso. En conclusión, se encuentran las condiciones óptimas para poder reducir al Cr(VI) en forma continua mediante el empleo de un reactor electroquímico de flujo ascendente.

In this research it is studied the electrochemical reduction of Cr (VI), in order to meet the discharge limits indicated in the environmental law. Experimental tests were done using a number of electrochemical reactors that use electrodes made of plain carbon steel. Three main variables were identified, pH, current density and flow, that significantly affects the reduction process of Cr (VI). Based on the chemical and thermodynamic characteristics of the systems Cr (VI)-Cr(III)-H2O-e- and Fe(III)-Fe(II)-H2O-e- the reduction process was optimized. A comparison between the classical chemical precipitation method and the electrochemical means was performed. Although both are based in the same general reaction: 3Fe (II ) (aq) + 3Cr (VI ) (aq) ↔ 3Fe (III) (aq) + Cr (III) (aq), the way in which the required amount of Fe(II) is added to the wastewater, is different for each method. In the chemical method, Fe(II)(aq) is supplied by dissolving FeSO4⋅7(H2O)(s) into the wastewater, while in the electrochemical process Fe(II)(aq) ions are formed directly in solution by anodic dissolution of an steel electrode. After this reduction process, the resulting Cr (III)(aq) and Fe(III)(aq) ions are precipitated as insoluble hydroxide species, in both cases, changing the pH using a 1M solution of calcium hydroxide . Experimental results shows that using both methods a Cr (VI) reduction efficiency of 99.5 % is possible to be achieve. However, the electrochemical option, apart from providing a better form of control, generates significantly less sludge as compared with the chemical process (60 %). Finally, a mathematical model that simulates the process is presented. As a conclusion, optimal conditions for continuous Cr (VI) reduction using a plug flow reactor are found.

Doctoral thesis

Sewage--Purification--Chromium removal. Chromium-plating--Waste disposal. Electrochemistry. Agua -- Purificación. TD758.5.H43 INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE CONTROL DE LA CONTAMINACIÓN DEL AGUA

Remoción de Color en Aguas Contaminadas con tintas, pretratadas electroquìmicamente mediante Ozono en medio alcalino

Francisco Zaldumbide-Ortiz CARLOS EDUARDO BARRERA DIAZ (2009)

En este artículo de investigación se muestran los resultados obtenidos en el tratamiento de aguas residuales que contienen disueltas tintas flexográficas, las cuales son empleadas en las industrias de colorantes. De inicio se propuso tratar este tipo de aguas electroquímicamente, pero los resultados mostraron que es necesario realizar un pretratamiento como primer paso, que en este caso particular fue el empleo de un coagulante, el policloruro de aluminio, para posteriormente aplicar el proceso electroquímico y finalmente como etapa de pulimiento se utilizo un tratamiento via Ozono. Los resultados obtenidos fueron interesantes, ya que dan un pauta de es lo que está sucediendo con los tratamientos propuestos para este tipo de agua residual.

En este artículo de investigación se muestran los resultados obtenidos en el tratamiento de aguas residuales que contienen disueltas tintas flexográficas, las cuales son empleadas en las industrias de colorantes. De inicio se propuso tratar este tipo de aguas electroquímicamente, pero los resultados mostraron que es necesario realizar un pretratamiento como primer paso, que en este caso particular fue el empleo de un coagulante, el policloruro de aluminio, para posteriormente aplicar el proceso electroquímico y finalmente como etapa de pulimiento se utilizo un tratamiento via Ozono. Los resultados obtenidos fueron interesantes, ya que dan un pauta de es lo que está sucediendo con los tratamientos propuestos para este tipo de agua residual.

Article

Estudios Territoriales Aguas Contaminadas Ozono Electroquímica CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Waste tire particles and gamma radiation as modifiers of the mechanical properties of concrete

EDUARDO SADOT HERRERA SOSA GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ EPIFANIO CRUZ ZARAGOZA (2014)

In polymer reinforced concrete, the Young’s modulus of both polymers and cement matrix is responsible for the detrimental properties of the concrete, including compressive and tensile strength, as well as stiffness. A novel methodology for solving such problems is based on use of ionizing radiation, which has proven to be a good tool for improvement on physical and chemical properties of several materials including polymers, ceramics, and composites. In this work, particles of 0.85mm and 2.80 mm obtained from waste tire were submitted at 250 kGy of gamma radiation in order to modify their physicochemical properties and then used as reinforcement in Portland cement concrete for improving mechanical properties. The results show diminution on mechanical properties in both kinds of concrete without (or with) irradiated tire particles with respect to plain concrete. Nevertheless such diminutions (from 2 to 16%) are compensated with the use of high concentration of waste tire particles (30%), which ensures that the concrete will not significantly increase the cost.

Article

Waste tire gamma irradiation Concrete Mechanical properties BIOLOGÍA Y QUÍMICA

Materiales reciclados de llantas automotrices y la radiacion gamma en el mejoramiento del concreto

EDUARDO SADOT HERRERA SOSA GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ EPIFANIO CRUZ ZARAGOZA (2015)

El concreto es uno de los materiales más importantes dentro de la industria de la construcción, esto se debe no solo a su costo sino a las propiedades que presenta como su fácil colocación antes del fraguado, su resistencia al intemperismo, su durabilidad y resistencia. En aras de reducir el impacto ecológico que genera la producción de cemento, se han hecho esfuerzos por disminuir el consumo de recursos naturales no renovables en la fabricación del concreto. En este capítulo se presenta como opción viable para la solución al problema causado por llantas de desecho su reuso en el concreto como sustituto del agregado fino o grueso, procurando la calidad del producto e incrementando las propiedades deseables como la resistencia, el módulo de elasticidad y la durabilidad.

Book part

Materiales reciclados Radiación Gamma Concreto Llantas BIOLOGÍA Y QUÍMICA

Waste materials from Tetra Pak packages as reinforcement of polymer concrete

MIGUEL MARTINEZ LOPEZ GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ FERNANDO UREÑA NUÑEZ WITOLD KONRAD BROSTOW (2015)

In this work, different concentrations (from 1 to 6 wt%) and sizes (0.85, 1.40 and 2.36 mm) of waste Tetra Pak particles replaced partially silica sand in polymer concrete. As is well known Tetra Pak packages are made up of three raw materials: cellulose (75%), low-density polyethylene (20%) and aluminum (5%). The polymer concrete specimens were elaborated with unsaturated polyester resin (20%) and silica sand (80%), and irradiated by using gamma rays at 100 and 200 kGy. The obtained results shown that compressive and flexural strength as well as modulus of elasticity decrease gradually, when either Tetra Pak particle concentration or particle size is increased, as regularly occurs in composite materials. Nevertheless, improvements of 14% on both compressive strength and flexural strength, as well as 5% for modulus of elasticity were obtained when polymer concrete is irradiated.

Article

Waste materials Tetra Pak Polymer concrete Mechanical properties BIOLOGÍA Y QUÍMICA

Effects on mechanical properties of recycled PET in cement-based composites

Liliana Ivette Ávila Córdoba GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ FERNANDO UREÑA NUÑEZ (2013)

Concretes consisting of portland cement (OPC), silica sand, gravel, water, and recycled PET particles were developed. Specimens without PET particles were prepared for comparison. Curing times, PET particle sizes, and aggregate concentrations were varied. The compressive strength, compressive strain at yield point, and Young modulus were determined. Morphological and chemical compositions of recycled PET particles were seen in a scanning electron microscopy. Results show that smaller PET particle sizes in lower concentrations generate improvements on compressive strength and strain, and Young’s modulus decreases when the size of PET particles used was increased.

Article

Recycled PET Composites Cement BIOLOGÍA Y QUÍMICA

Materiales provenientes del reciclamiento de envases de Tetra Pak y su uso en concreto

MIGUEL MARTINEZ LOPEZ GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ FERNANDO UREÑA NUÑEZ (2015)

Son escasos los estudios que involucran el uso de los materiales de reciclo de envases de Tetra Pak. No obstante, se ha estudiado la viabilidad del uso de polietleno de baja densidad (LDPE) y el aluminio reciclados de envases Tetra Pak para la fabricación de tableros rígidos utlizando una prensa caliente. En este capítulo se evaluó el efecto de las partículas de Tetra Pak en concretos poliméricos. Se realizaron ensayos de compresión y fexión, así como el cálculo del módulo de Young; con la finalidad de conocer el efecto de las partículas en la deformación.

Book part

Concreto Tetra Pak Radiación Gamma Reciclamiento INGENIERÍA Y TECNOLOGÍA

Recent developments in polymer recycling: en gamma rays: technology applications and health implications

GONZALO MARTINEZ BARRERA Elsa Carmina Menchaca Campos CARLOS EDUARDO BARRERA DIAZ Liliana Ivette Ávila Córdoba (2013)

Gamma-rays originate from the decay of excited states of the atomic nuclei in a similar manner as the visible light originates from the decay of the atom itself. Gamma rays belong to the class of ionizing radiation, together with alpha rays (doubly ionized atoms of helium) and beta rays (electrons). The spectroscopy of gamma rays, having the unique feature that by photoeffect transform their total energy to the energy of electrons in the detection material, contributed decisively to the establishing of the decay schemes of atomic nuclei. Strong sources of gamma radiation are widely used in contemporary technologies for cancer treatment, material modification, medical imaging, and food sterilization. The main goal of this book is to present to the non-specialist reader the contemporary applications of gamma rays by selected chapters on that issue. This book has 16 selected chapters from basic application of gamma rays to applied issues like food sterilization and polymer modification.

Book part

Technology Applications and Health Implications INGENIERÍA Y TECNOLOGÍA

Recovery and modification of waste tire particles and their use as reinforcements of concrete

EDUARDO SADOT HERRERA SOSA GONZALO MARTINEZ BARRERA CARLOS EDUARDO BARRERA DIAZ EPIFANIO CRUZ ZARAGOZA FERNANDO UREÑA NUÑEZ (2015)

Environmental pollution caused by solid wastes is increasing in the last decades; one of these is referred to automotive tires, which are recycled by differentmethods, includingmechanical grinding. One of the most recurrent applications is to use recycled particles as fillers in building materials, as hydraulic concrete. Nevertheless, detrimental values on the mechanical properties are obtained when they are added. For solving these problems, in this work, a novel proposal is to modify the physicochemical properties of the waste automotive tire particles, previously obtained by grinding process, by using gamma irradiation in order to use them as reinforcements of hydraulic concrete. The results show that improvements on the mechanical properties depend of gamma irradiation as well as concentration and size of waste tire particles. Moreover, SEMimages are related to mechanical properties; for instance, rough surface of the tire particles changes when applying irradiation; more smooth surfaces are created, due to the crosslinking of polymer chains.Nevertheless, for higher doses, cracks are observedwhich are produced by scission of the polymer chains.

Article

waste tire concrete reinforcement mechanical properties INGENIERÍA Y TECNOLOGÍA

Towards Sustainability: Photochemical and electrochemical processes applied for environmental protection

REYNA NATIVIDAD RANGEL CARLOS EDUARDO BARRERA DIAZ CARLOS ALBERTO MARTINEZ HUITLE JUAN MARTIN RODRIGUEZ RODRIGUEZ (2018)

In the last century, public policy around the globe was mainly focused on economic growth leaving out of this perspective, social concerns and the environment detriment that this merely economic approach was causing. It was until the last quarter of the 20th century that people started to be aware of the growing poverty and of the jeopardy of the planet as a result of human being activities. In consequence, the concept of sustainable development emerged in the United Nations as a call to all countries to integrate economic growth with social needs and environmental protection, in such a way that our activities as earth inhabitants stopped compromising the quality of life and needs satisfaction of future generations.

Article

sustainability: photochemical electrochemical environmental protection remediación de agua CIENCIAS SOCIALES