Envíos recientes

Instrumentación y Física de la Materia Condensada – GIFIMAC

|

Use of strontium aluminate powders in the photocatalytic removal of dyes present in water

Benítez Guerrero, N S | 2021-06-04

The removal of Iris No. 17 fabric dye in water using strontium aluminate powders doped with europium and dysprosium, and the radiation from an ultraviolet C lamp during photocatalysis, is reported. The degradation of the dye was studied by UV-Vis spectrophotometry, for two concentrations of strontium aluminate powder and five of the dye for one hour. The chemical composition and morphology of strontium aluminate powders was studied using X-ray scattered energy spectroscopy, X-ray fluorescence and scanning electron microscopy. The pH, total dissolved solids, and electrical conductivity of the water samples before and after treatment were measured using the Handy-Lab 680 multiparameter. It is evident in the morphology of the strontium aluminate powders a synthesis by reaction in solid state, and a chemical composition by weight of strontium oxide and small amounts of europium and dysprosium. The photocatalytic treatment reports an efficiency of 100% in the removal of the dye for the strontium aluminate powder concentration of 500 mg/L, while for 1000 mg/L an efficiency of 98% was found, likewise for a concentration of 60 mg/L and one hour of ultraviolet radiation a first order reaction kinetics in the degradation of the dye was evidenced.

Effective thermal properties and proximate analysis of coke-coal fines mixtures

Soto Rivero, M F | 2021-06-04

We report the effective thermal properties at room temperature and proximate analysis of three mixtures of coke and carbon fines formed by uniaxial pressing at 30 MPa. Using differential scanning calorimetry and thermogravimetry, the thermal behavior of the carbon samples was determined. The KD2 Pro® system was used to measure the effective thermal properties, while the proximate analysis was carried out applying the ASTM D 3172-89 standard. It was found for coke fines that in the range between 40.00 °C and 293.94 °C there is a loss in weight of 3.2%, which corresponds to the degradation of low molecular weight volatiles, another degradation was also observed between 90.07 °C and 336.21 °C, and the maximum devolatilization temperature was 579 °C, finally from 700 °C the melting process begins, which corresponds to the formation of coke. It was also observed that the thermal conductivity increases with increasing coke concentration in the sample, and that the mixture with the highest thermal diffusivity was the one formed with 80% coke fines and 20% carbon fines. According to the thermal properties of the samples can be to be used efficiently as fuel.

Silver colloidal nanoparticles by electrochemistry: temporal evaluation and surface plasmon resonance

Padilla Sierra, H A | 2021-06-04

The electrochemical technique for obtaining silver nanoparticles has advantages over other methods. For the synthesis, a colloidal silver generator (Colloidal Silver Generator® model 1001) was used, where two electrodes coupled to high purity silver rods (99.99%) were used, with a potential difference of 24 V. Nanoparticle concentration was measured by total dissolved solids, using the SI-Analytic HandyLab 680 FK multiparameter in 200 mL of Milli-Q deionized water, reporting 18 ppm at 1 hour at room temperature. The determination of the resonance wavelength of the surface plasmons was carried out by finding the maximum absorbance by UVVisible spectrophotometry with λ = 423 nm. The morphology and size of the nanoparticles was determined by Transmission Electron Microscopy, observing spherical morphology and sizes smaller than 50 nm. The chemical composition was determined by X-ray energy dispersed spectroscopy, finding a weight concentration of 93.22% of silver. The results show an optimal synthesis of colloidal silver, with characteristics that will allow the inhibition of microorganisms of interest.

Electrochemical synthesis of titanium dioxide nanostructures and its application in the in dye photocatalytic removal

RIVERA BERMUDEZ, INGRID PAOLA | 2021-06-04

By electrochemical anodization to titanium sheets, titanium dioxide nanostructures were sintered for 10 V and 20 V and times of 3 hours and 5 hours. For the electrolytic solution, 0.3 g of ammonium fluoride, 97 mL of ethylene glycol and 3 mL of distilled water were used. The sheets (51 mm × 21 mm × 0.4 mm) were treated using abrasive paper and cleaned with a 1:1 solution of ethanol water by means of ultrasound and dried using hot air. A stirring frequency of 300 rpm was used during anodizing. For the sintering of the titanium dioxide anatase phase, heat treatment was applied at 550 °C for 3 hours by means of an electric muffle, with heating speed of 10 °C/min. The crystallinity index, and the quantification of the sintered phases was carried out by means of X-ray diffraction, while the nanoporosities and their distribution were carried out using imageJ software to the images taken by means of scanning electron microscopy. For the photocatalytic treatment of the methylene blue dye in water, the titanium dioxide nanostructures that reported the highest anatase phase were used, where ultraviolet C radiation from a led lamp was applied for 4 direct hours. The efficiency in the removal of the dye was studied by UV-Vis spectrophotometry, finding the highest degradation of the dye for the wavelength of 644 nm.

Elaborar y caracterizar pastas cementantes fosforescentes a base de geopolímeros dopados con aluminatos de estroncio para aplicaciones ambientales

Peña Rodriguez, Gabriel | 2021-08-25

Dentro de las técnicas de tratamiento de aguas y aires, existe la fotocatálisis o fotoelectrocatalisis, donde el principio físico es la interacción de la radiación con la materia, utilizándose la radiación UV proveniente del sol. Por lo anterior, se pretende elaborar y caracterizar morfológica, estructural, térmica, mecánica y ópticamente muestras de una pasta cementante fosforescente a base de geopolímeros dopadas con aluminatos de estroncio, para concentraciones en peso del 10, 20 y 30%. La pasta cementante se elaborará agregando caolín y solución salina de silicato de sodio con hidróxido de sodio, para lo cual se agitará mediante agitador de cabezal a 800 rpm. Una vez obtenida la pasta cementante se agregarán las concentraciones definidas de los polvos comerciales de aluminato de estroncio, y se elaborarán las probetas para su respectiva caracterización. Lo anterior se realizará por triplicado con el objeto de disminuir las incertidumbres en las medidas experimentales. La caracterización estructural se realizará mediante difracción de rayos X (DRX), la morfología y microanálisis usando microscopia electrónica de barrido (EDS-MEB), las térmicas a temperatura ambiente mediante flujo transitorio plano de calor, y las ópticas mediante la irradiación con lámpara UV de 15W acoplada a una cámara web de alta definición, la cual registrara el tiempo de emisión de la fosforescencia de la muestra para un tiempo definido de irradiación, en función de la concentración del aluminato de estroncio. Lo anterior permitirá definir las mejores condiciones, para que la pasta pueda ser utilizada en revestimientos o tanques para el tratamiento de aguas o gases mediante fotocatálisis o fotoelctrocátalisis, ya que dicho proceso puede ser dado en doble vía, primero con la interacción directa de la radiación sobre el semiconductor (aluminato de estroncio), y posteriormente en ausencia de la radiación debido a la fosforescencia emitida; otra de las aplicaciones de la pasta fosforescente es de auto-iluminación donde absorberá radiación durante el día y la emitirá en la oscuridad, sirviendo como demarcación o señalización, en construcciones civiles o vías

Elaboración y caracterización de recubimientps de polvos de ZnSCu y resinas de poliester sobre sustratos cerámicos de arcilla roja, para el diseño de fachadas y revestimientos arquitectónicos fosforescentes

Ferrer, Martha | 2018

En este estudio se elaboran y caracterizan recubrimientos de polvos ZnSCu y resinas de poliéster termoestables sobre sustratos cerámicos de arcilla roja, para el diseño de fachadas y revestimientos arquitectónicos fosforescentes. Los recubrimientos se conforman a partir de mezclas de polvos, resina y catalizador en diferentes porcentajes. Se estudia sus propiedades en función de la concentración del polvo agregado a la mezcla. La información comparativa de las diferentes concentraciones de polvo fosforescente y resina de poliéster permiten determinar no solo su caracterización, sino también la toma de decisiones en el diseño y aplicación en futuras propuestas arquitectónicas, relacionadas con fachadas o revestimientos que absorban luz ultravioleta o solar durante el día y su fosforescencia durante la noche.

Manufacturing of Photoactive β-Bismuth Oxide by Flame Spray Oxidation

Ferrer, Martha | 2021-03-21

Photoactive tetragonal bismuth oxide powder with different semiconducting characteristics was synthesized from Bi-pellets by flame spray oxidation. The effect of feedstock particle size and standoff distance (SOD) on the physical properties of β-Bi2O3 keeping constant the fuel/oxygen ratio is here reported. The flame spray oxidized powder was collected either from evaporated or in-flight particles quenched in water. The combination of flame spray processing parameters led to different β-Bi2O3 phase contents, oxidation characteristics, size distribution (nanometric and micrometric sized), morphology, and optical properties of the sprayed powder. The highest micrometric β-Bi2O3 content quenched in water was obtained at a SOD of 30 cm using a particle size distribution of 12-60 μm of Bi-feedstock. The obtained powder from in-flight particles collected in water allowed us to analyze the oxidation characteristics of bismuth. Micrometric powder shows the synthesis of snowman-like Bi/β-Bi2O3 Janus particles. The nanometric sized Bi2O3 powder was continuously obtained by spray oxidation, where its collection efficiency depends on processing parameters and showed spherical morphology and a highly pure tetragonal phase with narrow visible light absorbance (Eg = 2.26 eV). These optical characteristics indicate that the obtained β-Bi2O3 powder is suitable for high-performance visible-light photocatalyst.

Ultrasound irradiation effect on photosynthesis and transpiration of aquatic lirium plants

Calderón, José Antonio | 2021-08-23

To find possible causes of the photobaric response decrease in photoacoustic measurements on Aquatic Lirium plants after ultrasonic irradiations reported elsewhere contributing to understanding the effect of ultrasonic irradiation on them and searching for environmentally friendly methodologies to control this weed.

Structure, mechanical and thermal behaviour of mixtures of polyester resin and dental ceramic waste

Peña Rodriguez, Gabriel | 2016-02-12

The tensile strength and bending strength, structure and thermal behaviour of mixtures of polyester resin (P-2000) and powders (ASTM sieve 200, <75μm) of dental ceramic wastes (dentals impressions, alginate and gypsum) was reported. The samples consisted of mixtures with percentage weights of 50-50%, 60-40%, 70-30%, 80-20%, 90-10%, where the resin was the majority phase, the Mekc (4% wt) was used as catalyst. The structure was studied using SEM and XRD, the thermal behaviour using DSC, TGA and DMA, while the mechanical strength was tested using standards ASTM D790 and D638. Irregular morphology and presence of small agglomerations was observed, with particle sizes between 29.63 and 38.67μm, the presence of different phases of calcium sulphate was found, and that to the increasing the concentration of the powder, the materials becomes more crystalline, increasing its density. An average service temperature of 69.15±4.60°C was found. Vickers hardness values are reported in ranges from 18.65 to 27.96. Considering the elastic modules was established that the materials become more rigid by having more powder concentration.

Electrochemical characterization of the steel wire used as reinforcement in the conductors transmission networks electricity nitride by ion implantation

Hector Jaime, Dulce-Moreno | 2016-02-12

The power company feature infrastructure, which are generally shaped so the transmission and distribution lines, here is why it is necessary to characterize the process of electrochemical corrosion of these components. In this case the steel wire coated with zinc or aluminium, as it is undergoes the rigor of corrosive environments. Given the geographical diversity and different climatic environments, atmospheric corrosion carried affecting service life of structures. For example in very humid environments such as coasts and high altitudes, wetting time (TOW), parameter that meets the conditions of temperature and relative humidity, it affects large proportion, accelerating the corrosion of ferrous materials. Given the importance of establishing mechanisms that lessen the impact on degradation in transmission and distribution lines of both the reliability and the availability of the same. This paper presents the implementation in nitride steels as an alternative or complement to zinc coating.

ForistomApp a Web application for scientific and technological information management of Forsitom foundation

Hector Jaime, Dulce-Moreno | 2017-12-29

Information and Communication Technologies (ICT) are essential in the transfer of knowledge, and the Web tools, as part of ICT, are important for institutions seeking greater visibility of the products developed by their researchers. For this reason, we implemented an application that allows the information management of the FORISTOM Foundation (Foundation of Researchers in Science and Technology of Materials). The application shows a detailed description, not only of all its members also of all the scientific production that they carry out, such as technological developments, research projects, articles, presentations, among others. This application can be implemented by other entities committed to the scientific dissemination and transfer of technology and knowledge.

Mechanical and tribological behavior of red clay ceramic tiles coated with fly ash powders by thermal spraying technique

Peña Rodriguez, Gabriel | 2017

The mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxy-fuel thermal spraying process from fly ash powders was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 26.17 bar pressure, and sintered at 1100 °C. The coating thickness was determined based on the number of projection-cycles oxyacetylene flame over substrate. Coal fly ash coatings were deposited, with average thickness of 56.18±12.18 μm, 180.42±20.32 μm, and 258.26±25.88μm. The mechanical resistance to bending and wear by abrasion deep, were studied using ISO 10545-4 standards and ISO 10545-6 respectively; adhesion was measured using Elcometer equipment Type III according to ASTM D-4541-02 and the average roughness (Ra) was found according to ASTM standard D7127-13, using the profilometer Mitutoyo SJ 201. The surface morphology presented the heterogeneous molten or semi molten splats with average size of 35.262±3.48 micrometers with good adhesion, justifying increased mechanical resistance to bending by 5%, as well as wear by abrasion deep. These results contribute to the development of ceramic products with added value, to be used in various technological applications.

Effect of surface roughness on nitriding processes by dielectric barrier discharges of carbon steel

Hector Jaime, Dulce-Moreno | 2017-12-29

Changes in the behaviour of steels to carbon, for three different finishes, surfaces were determined to be nitride by atmospheric pressure dielectric barrier discharge. The surfaces were characterized both morphologically and structurally before and after the treatment. The techniques used were: measurement of roughness and electrochemical testing (Tafel). Results show changes differential depending on the type of finish, but in any case, an improvement of corrosion resistance.

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Hector Jaime, Dulce-Moreno | 2017-12-29

Evaluated the wear resistance and the coatings corrosion behaviour of Al2O3-TiO2 prepared by thermal spraying by flame on AISI 1020 carbon steel substrates, previously coated with an alloy base Ni. For this purpose, were controlled parameters of thermal spraying and the use of powders of similar but different chemical composition is taken as a variable commercial reference for ceramic coating. SEM images allowed to know the morphology of the powders and coatings. Electrochemical techniques (Tafel) were applied to evaluate the protection against corrosion. Coatings were tested for wear with a tribometer configuration bola-disco. It was determined that the phases present in coatings are directly relate to the behaviour against corrosion and wear them. Keywords: wear, corrosion, thermal imaging.

Optimization of the parameters for obtaining zirconiaalumina coatings, made by flame spraying from results of numerical simulation

Peña Rodriguez, Gabriel | 2017-12-29

The K-Sommerfeld values (K) and the melting percentage (% F) obtained by numerical simulation using the Jets et Poudres software were used to find the projection parameters of zirconia-alumina coatings by thermal spraying flame, in order to obtain coatings with good morphological and structural properties to be used as thermal insulation. The experimental results show the relationship between the Sommerfeld parameter and the porosity of the zirconia-alumina coatings. It is found that the lowest porosity is obtained when the K-Sommerfeld value is close to 45 with an oxidant flame, on the contrary, when superoxidant flames are used K values are close 52, which improve wear resistance.

Projection parameters for zirconia-alumina-ceria coatings made by flame spraying from results of numerical simulation

Peña Rodriguez, Gabriel | 2017-12-29

A numerical simulation was performed with the software Jets et Poudres, the results let choose the parameters to deposit zirconia-alumina-ceria coatings of different composition on substrates of red clay, by thermal spraying with the oxyacetylene flame to obtain homogeneous coatings with good adhesion to the substrate. The effect of the projection distance (7, 10 and 12cm) between the substrate and the torch, the fusion percentage of particles and the K-Sommerfeld number was determined. This number is dimensionless and is affected by the projection distance and by the chemical composition of the particles. For a projection distance of 9cm, the fusion percentage of the particles varies between 83.8% and 100%, and the K-Sommerfeld number between 47.3 and 50 for the different compounds. This makes possible to obtain uniform coatings with good wettability, therefore, good adhesion to the substrate, while for the distance of 7cm the fusion percentage varies between 22% and 38%, due to the short time of the particles in the flame which causes low adhesion, when the projection distance is 12cm the particles do not have sufficient kinetic energy to reach the substrate and therefore the coating is not deposited.

Efecto de la concentración de magnetita en la estructura, propiedades eléctricas y magnéticas de un material compuesto a base de resina de poliéster

Peña Rodriguez, Gabriel | 2018-01-15

Se reporta el efecto de la concentración de polvos de magnetita (Fe3O4) sobre las propiedades eléctricas y magnéticas de un material compuesto a base de resina de poliéster termoestable. Las muestras se elaboraron mediante el método de colado manual en concentraciones de: 60-40, 70-30, 80-20, 90-10 y 100-0 (% en peso), donde la fase mayoritaria es la resina y la minoritaria los óxidos de Fe3O4. La estructura cristalina se estudió usando la técnica de difracción de rayos X y la caracterización superficial tuvo lugar a través de la técnica de microscopía electrónica de barrido. Se midió la respuesta eléctrica por medio de curvas de polarización eléctrica en función del campo eléctrico y de resistividad eléctrica volumétrica a través de un electrómetro. La respuesta magnética se determinó mediante curvas de magnetización en función de la intensidad de campo magnético aplicado y en función de la temperatura. El análisis estructural indica que el porcentaje de cristalinidad aumenta a medida que se adiciona la concentración de Fe3O4 a las muestras. La caracterización eléctrica del material evidencia que la resistividad volumétrica disminuye con el incremento de magnetita, mostrando una transición aislante-conductor, con valores de la constante dieléctrica cada vez mayores. La caracterización magnética evidencia un aumento lineal de la magnetización de saturación y del momento magnético en función de la cantidad de magnetita adicionada a la matriz polimérica, mientras que la coercitividad evidencia comportamientos de materiales magnéticos blandos tanto en T˃TV como en T<TV, donde TV representa la temperatura de Verwey

Manufacture of oxy-acetylene thermally sprayed coating on refractory subtrates from unconventional feedstock material

Cadavid, Edwin | 2018-04-01

A chromite mineral and two industrial residues produced in the petrochemical and thermoelectric industries, were selected, characterized, processed and deposited on refractory bricks. By means of X-ray fluorescence and X-ray diffraction the chemical composition and crystallographic phases of raw materials were analyzed, morphology and particle size was determinate using Scanning Electron Microscopy. The materials were deposit by oxyacetylene thermal spray on silica-alumina refractory bricks and high alumina low cement concrete, commercial references ER-40 and CBC-50 from ERECOS S.A.S.. The parameters used for the coating deposition were optimized based on preliminary test and simulations using the Jets&powders software. The chromite mineral coating displayed greater structure homogeneity than the other two coatings; the last ones presented partially melted particles and high porosity. However, based on the chemical composition, the response to adhesion test and the crystallographic phases present in the coatings, all of them are potential candidates to be used as protective barriers against corrosive effects on refractories.

Porous covering compound of clay matrix and coal ashes

Peña Rodriguez, Gabriel | 2018-11-05

Here are presented the elaboration and characterization of a composite material with an atomized ceramic paste and flying ashes product of the coal combustion. The samples consist of prismatic tiles of 10x5x1 cm, formed by uniaxial pressing at 30 bars, made for mixes with a percentage weight of 90-10, 80-20, 70-30, 60-40 and 50-50, where the majority phase corresponds to the atomized ceramic paste. The drying process was conducted at room temperature for 12 hours and then in drying oven at 110 ° C for 24 hours. The sintering was carried out in gradient electric muffle at a maximum temperature of 1150 °C. According to the porous morphology and mechanical properties found for samples, this can be used as ceramic coatings with thermal isolation qualities for edifications in tropical weather like the metropolitan area of Cucuta, North Santander (Colombia)

Water treatment using porous ceramics based on recycled diatomite and kaolin

MOGOLLON CUELLAR, ZULMA YARLEY | 2018-09-06

The treatment of waters using filtering process through sintered porous ceramics based on diatomite and kaolin is reported. The water samples were prepared in low = 50%, medium = 100% and high = 150% concentrations, taking as reference point the maximum value allowed according to the resolution 2115 - 2007. The treated parameters were alkalinity; hardness to calcium, magnesium and total; chlorides; sulfates and total iron. The porous ceramics were formed by slip casting in plaster mold, from pastes with weight percentage of 50% recycled diatomite from the beer industry, 40% kaolin and 10% calcium carbonate. The particle sizes of the ceramic powders were the passed through ASTM 200 sieve. The drying of the ceramics was carried out at room temperature for 24 h, then by forced circulation oven Memmert UF-110 at 100 ° C for an equal time. The sintering of the ceramics was carried out in Vulcan D-130 electric muffle, at a maximum temperature of 1000 ° C for two hours, with a heating ramp of 10 ° C/min. The morphology of the ceramics was studied using scanning electron microscopy (SEM), while the physic ceramic analyses was evaluated according to ISO 10545-3 standard. Our results, reported what porous ceramics efficiency for the removal of chlorides up to 50%, while elimination of sulfates was approximately 43%, on the other hand, the total iron was removed up to 95%, likewise,it was evidenced that ceramics are not efficient in the treatment of hardness and alkalinity of waters with high concentrations