11 research outputs found
Strategic Design of Heavy Metals Removal Agents through Zeta Potential Measurements
Industrial wastewater generally contains significant amounts of toxic heavy metals that cause a problem of contamination to the environment. In this chapter, the use of polyelectrolytic waste as new coagulant-flocculating-chelating agents in the separation of Cu, Ni, Zn, Pb, Cd, Cr by a coagulation-flocculation process is discussed. The isoelectric point (味聽=聽0) of the residual water was reached with a dose of 2.5聽mg chitosan and observed a clarification kinetics聽=聽187.49% T/h, sediment kinetics聽=聽93.96聽mm/h and an efficiency of 85% in the removal of heavy metals. With the SEM-EDS analysis and the determination of heavy metals in the treated water, it is shown that the functional groups that chitosan has in its structure have the following order of affinity for the removal of heavy metals from the wastewater model: Cr聽=聽27.64%聽>聽Ni聽=聽21.96%聽>聽Pb聽=聽21.28%聽>聽Zn聽=聽14.68%聽>聽Cu聽=聽10.96%聽>聽Cd聽=聽3.35%聽>聽Ca聽=聽0.12%
Innovation in the Electrophoretic Deposition of TiO2 Using Different Stabilizing Agents and Zeta Potential
Surface engineering is gaining increasing relevance in various industrial sectors and in research, and in this sense, zeta potential measurements, being a physicochemical parameter of interface, are key to linking the functionality of a coating with its application environment. In this work, different stabilizing agents with different chemical structure and electrical charge were used to improve the stability of the TiO2 particles. The influence of the electrophoretic deposition (EPD) parameters (potential and deposition time) and the concentration of chitosan and TiO2 in suspension were studied to find the best deposition performance on the titanium substrate. The composition and structure of the coatings were evaluated by infrared spectroscopies (FT-IR) and scanning electron microscopy (SEM). It was observed that the TiO2 particles were dispersed in the chitosan matrix through simultaneous deposition. Corrosion resistance was evaluated by electrochemical polarization curves, indicating a higher corrosion resistance of TiO2 and TiO2-chitosan coatings compared to the pure titanium substrate in a solution of sulfuric acid
Integral use of Nejayote: Characterization, New Strategies for Physicochemical Treatment and Recovery of Valuable By-Products
In this research, an innovative physicochemical strategy is presented to address the problem of nejayote, from two perspectives: the first focusing on sanitation and reuse of nejayote using waste from shrimp shells, thereby adding value to the recovered solids of nejayote. Zeta potential measurements are a proactive electrochemical tool to define the strategy to allow integral use of nejayote in the industry nixtamalization. The treated water can be discharged from the municipal sewer system using a process of coagulation-flocculation, with an optimal dose of 1250 mg/L chitosan at pH 5, achieving removal of up to 80% of total suspended solids and turbidity. Moreover, zeta potential measurements show that the anionic biopolyelectrolyte obtained from nejayote has potential to be applied in the area of water treatment as a green chelating agent
Chalcogenides and Carbon Nanostructures: Great Applications for PEM Fuel Cells
Nanostructured metal chalcogenides (NMCs) and carbon nanostructures (CNS) are attracting significant attention due to their features such as high stability in an acidic environment, especially if they have a significant oxygen reduction activity and remarkable superconducting properties. The broad range of CNS exhibits novel physicochemical properties, and thus it is triggering intense research about carbon nanoscience with numerous applications. In this context, new synthesis routes are designed under moderate conditions, which are definitely needed in order to simplify the process, reduce costs, and allow the production of NMCs at lower temperatures and CNS whose size and shape can be controlled. Some related studies about Pt based on sulfides and selenides, transition metal chalcogenides (TMCs), and carbon nanostructures (nanotubes and graphene) are revealed here; however, they show promise for fuel cells that these NMCs, CNS, or even NMC-CNS materials have been applied for other energy devices. Until now, a good response for cathodic reactions is employing TMCs based on tungsten and CNS without metal. According to experimental results and in terms of catalytic activity, durability, and chemical/electrochemical stability, much more research is required to produce commercially valid non-noble catalysts, electrocatalysts, or supports; however, one approach on this field is metal-free CNS
Evaluaci贸n de polisac谩ridos en floculaci贸n mediada por complejo polielectrol铆tico
Water is an increasingly valuable resource because its availability, primarily it is limited to precipitation and water storage; for that reason, increasing population density and climate change can interfere with water accessibility. Urban and industrial activities can produce wastewater and pollute waterbodies that could represent a significant water source; however, it needs to be treated prior to its use.聽 Flocculation is an important pollutants removal method to reduce a variety of organic and inorganic molecules from wastewater, using the flocculant鈥檚 intrinsic charges to stabilize/precipitate them, by different methods, one of them being via polyelectrolyte complex. Flocculant versatility depends on its capacity to remove pollutants and there are commercial flocculants with remarkable efficiencies. However, their toxicity can limit their use in waterbodies or for former human use. Research shows that polysaccharides are great option as flocculants because of their easily charged conformation and high molecular weight to neutralize pollutants and precipitate flocs, they are biocompatible, biodegradable, and easy to modify to modulate the flocculant interaction due to the functional group鈥檚 high density. This review explores the latest research on polysaccharide polyelectrolyte flocculation and derivatives and their pollutant removal capacity, the polysaccharides evaluated were the most commonly researched such as chitosan, cellulose, chitin, alginate, gums, dextran, among others. Recent research tendencies on these polysaccharides flocculation capacity, showed promising results (up to 99% removal efficiencies) with a wide variety of contaminants, making them excellent candidates for their application in green flocculation
Estudio de propiedades fotof铆sicas de sensores del tipo bis-fluoroforicos y su aplicaci贸n en la detecci贸n de iones met谩licos
Industrialized cities like Tijuana dispose of a large amount of water with metallic elements content, as a result of by-products, which represent a health risk. A proposed alternative is the use of chemical sensors based on different mechanisms. The focus of this project is the study of bis-o-aminobenzamide macromolecules, as metal ion selector sensors with application in wastewater treatment. A series of five bis-o-aminobenzamide compounds were studied as chemical sensors capable of selecting and coordinating with metals dissolved in water, in addition to being able to remove these metals in the presence of the natural coagulant Pectin, which was extracted from the penca of the nopal. For this, different concentrations of the five compounds were prepared, the most suitable for the analyzes was selected and it was contacted with solutions of different ions. The compounds and their coordination were evaluated by fluorescence, UV-Visible and Zeta potential spectroscopies. In addition, SEM micrographs were obtained upon removal obtained. The five sensors evaluated have different fluorescence intensities. When in contact with some metal ions, a coordination was formed that reduces the emission of fluorescence. Fluorescent properties in solution were studied by varying the concentration of ligand and the study of its interaction with different metals of environmental interest was carried out. The influence of the nature of the central chain of interconnection on the fluorescent properties of the studied library was determined. These ligands have interesting fluorescent characteristics, which gives them a potential value as sensors for metals, presenting a sensitivity for the Cu +2 ion in all cases.Las ciudades industrializadas como Tijuana desechan gran cantidad de agua con contenido de elementos met谩lico, resultado de los subproductos, que representan un riesgo para la salud. Una alternativa propuesta es el uso de sensores qu铆micos basados en diferentes mecanismos. El enfoque de este proyecto es el estudio de macromol茅culas bis-o-aminobenzamida, como sensores selectores de iones met谩licos con aplicaci贸n en el tratamiento de aguas residuales. Se estudi贸 una serie de cinco compuestos bis-o-aminobenzamidas como sensores qu铆micos capaces de seleccionar y coordinar con metales disueltos en el agua, adem谩s de poder remover estos metales en presencia del coagulante natural Pectina la cual fue extra铆da de la penca del nopal. Para ello se prepar贸 distintas concentraciones de los cinco compuestos, se seleccion贸 la m谩s adecuada para los an谩lisis y se puso en contacto con soluciones de distintos iones. Los compuestos y su coordinaci贸n fueron evaluados por espectroscopias de fluorescencia, UV-Visible y potencial Zeta. Adem谩s, se obtuvo micrograf铆as SEM a la remoci贸n obtenida. Los cinco sensores evaluados presentan distintas intensidades de fluorescencia, al estar en contacto con algunos iones met谩licos se formaba una coordinaci贸n que abate la emisi贸n de fluorescencia. Se estudiaron las propiedades fluorescentes en soluci贸n variando la concentraci贸n de ligando y se realiz贸 el estudio de su interacci贸n con diferentes metales de inter茅s ambiental. Se determin贸 la influencia de la naturaleza de la cadena central de interconexi贸n en las propiedades fluorescentes de la biblioteca estudiada. Estos ligandos presentan caracter铆sticas fluorescentes interesantes, lo que les confiere un valor potencial como sensores para metales, presentando una sensibilidad para el ion Cu+2 en todos los casos
Preparaci贸n de materiales funcionalmente graduados por deposici贸n electrofor茅tica
The objective of this work is to develop a superhydrophobic and self-healing coating with the ability to protect metal surfaces and extend the useful life of both metal and coating. By means of the electrophoretic deposition technique, titanium dioxide coatings with variable morphology and composition were created. So far two techniques have been used for the manufacture of superhydrophobic coatings: 1) Functionalization of TiO2 nanoparticles (anatase) with polydimethylsiloxane by UV irradiation and 2) Functionalization of electrophoretic deposits with polydimethylsiloxane by UV irradiation. The electrophoretic deposits vary the applied potential and the deposition times, they are observed that they are used, they are eliminated, the uniforms are uniform and homogeneous, they are minimized, they are reduced, they are diminished, they are diminished, they are diminished, they are increased, they are they increase, they increase, they increase, they decrease, they increase, they are deposited first, thus generating a homogeneous arrangement on the surface of the highly rough metal.聽 All deposits were characterized by FTIR, RAMAN, DLS, UV-vis- Diffuse Reflectance, AFM y FESEM.El objetivo de este trabajo es desarrollar un recubrimiento superhidrof贸bico y autoregenerable con la capacidad de proteger superficies de titanio y extender la vida 煤til tanto del metal como del recubrimiento. Mediante la t茅cnica de deposici贸n electrofor茅tica se crearon recubrimientos de di贸xido de titanio con morfolog铆a y composici贸n variable. Hasta el momento se han empleados dos t茅cnicas para la fabricaci贸n de los recubrimientos superhidrofobicos: 1) Funcionalizaci贸n de nanopart铆culas de TiO2 (anatasa) con polidimetilsiloxano por irradiaci贸n UV y 2) Funcionalizaci贸n de los dep贸sitos electrofor茅ticos con polidimetilsiloxano por UV. Los dep贸sitos electrofor茅ticos se prepararon variando el potencial aplicado y los tiempos de deposici贸n, se observa que al utilizar potenciales menores los dep贸sitos son m谩s uniformes y homog茅neos, se logra observar tambi茅n que las grietas disminuyen significativamente con la disminuci贸n del potencial aplicado debido a que las part铆culas m谩s peque帽as se depositan primero generando as铆 un arreglo homog茅neo en la superficie del metal altamente rugoso. Los dep贸sitos fueron caracterizados por diferentes t茅cnicas: FTIR, RAMAN, DLS, UV-vis de reflectancia difusa, AFM y FESEM
Improving the Efficiency of a Coagulation-Flocculation Wastewater Treatment of the Semiconductor Industry through Zeta Potential Measurements
Efficiency of coagulation-flocculation process used for semiconductor wastewater treatment was improved by selecting suitable conditions (pH, polyelectrolyte type, and concentration) through zeta potential measurements. Under this scenario the zeta potential, 味, is the right parameter that allows studying and predicting the interactions at the molecular level between the contaminants in the wastewater and polyelectrolytes used for coagulation-flocculation. Additionally, this parameter is a key factor for assessing the efficiency of coagulation-flocculation processes based on the optimum dosages and windows for polyelectrolytes coagulation-flocculation effectiveness. In this paper, strategic pH variations allowed the prediction of the dosage of polyelectrolyte on wastewater from real electroplating baths, including the isoelectric point (IEP) of the dispersions of water and commercial polyelectrolytes used in typical semiconductor industries. The results showed that there is a difference between polyelectrolyte demand required for the removal of suspended solids, turbidity, and organic matter from wastewater (23.4鈥塵g/L and 67鈥塵g/L, resp.). It was also concluded that the dose of polyelectrolytes and coagulation-flocculation window to achieve compliance with national and international regulations as EPA in USA and SEMARNAT in Mexico is influenced by the physicochemical characteristics of the dispersions and treatment conditions (pH and polyelectrolyte dosing strategy)
Polylactic acid/multi walled carbon nanotubes (PLA/MWCNT) nanocomposite for 3D printing of medical devices
In recent years, the composite nanomaterials area has had a great development impact in health sciences. Biomaterials depict as one of the most promising since they are compatible with additive manufacturing (AM) techniques. It is also possible to use them to mold specific medical parts. Composite nanomaterials have shown good biocompatibility and low toxicity to have benefits equal to or greater than metals (i.e., Co-Cr alloy). The purpose of this study is to develop a nanocomposite biomaterial (PLA/MWCNTf) from Polylactic Acid (PLA) and functionalized Multi Walled Carbon Nanotubes (MWCNTf) to evidence its potential application in 3D printing of orthopedic fixation devices. PLA/MWCNTf nanocomposite was prepared by solution blending technique, incorporating a proportion of 0.5 wt% of MWCNTf to the PLA matrix. TGA analysis of the PLA/MWCNTf was used to determine the thermal stability, a slight increase was found compared to the PLA.聽 FTIR spectroscopy confirmed the presence of carboxylic acid groups in the MWCNTf which improves good incorporation of the nanotubes in the PLA matrix. Additionally, Raman spectroscopy, SEM, and AFM micrographs were used to verify MWCNTf reached the PLA surface homogeneously. Additive manufacturing preparation was done by extrusion molding of PLA/MWCNTf as well as its 3D printing.聽
Evaluaci贸n de compuestos bis-fluorof贸ricos en agua del r铆o Tijuana
This work focuses on the use of bis-fluorophore compounds in real water for the detection and removal of metal ions present in the Tijuana river, for this, a previous work of chemical and bacterial analysis of 6 different samples that were taken from the River was used Tijuana. All the sampling sites were carefully selected to obtain an accurate understanding of the current state of the river throughout its course. The TOC, COD, BOD, Nitrogen and phosphorus results showed that dams do not contain high amounts of these parameters, but in the city, center these values are increased due to the possible interversion of city sewer connections to the river (55, 189, 131, 11.9 and 1.1 mg / L, respectively). The points with the highest amount of organic matter were in the city center, so that specific point was chosen for the test of bis-fluorophoric compounds, to ensure the presence of metal ions in the water and it was shown that the water containing fluorescent compounds and in the presence of these bis-fluorophoric compounds there is a lowering of fluorescence. The bacterial analysis showed that the last point of the city, near the border of the USA and Mexico, concentrates a high number of bacteria and that the discharge goes directly to the Pacific Ocean, being a health and environmental problem.Este trabajo se centra en el uso de compuestos bis-fluorof贸ricos en agua real para la detecci贸n y remoci贸n de iones met谩licos presentes en el r铆o Tijuana, para esto se utiliz贸 un trabajo previo de an谩lisis qu铆mico y bacteriano de 6 muestras diferentes que se tomaron del R铆o Tijuana. Todos los sitios de muestreo fueron seleccionados cuidadosamente para obtener una comprensi贸n precisa del estado actual del r铆o a lo largo de su curso. Los resultados de TOC, DQO, DBO, Nitr贸geno y f贸sforo mostraron que las presas no contienen cantidades elevadas de estos par谩metros, pero al centro de la ciudad estos valores se incrementan por la posible interversi贸n de conexiones del alcantarillado de la ciudad al r铆o (55, 189, 131, 11.9 y 1.1 mg/L, respectivamente). Los puntos con mayor cantidad de materia org谩nica fueron en el centro de la ciudad, por lo que se eligi贸 ese punto en espec铆fico para la prueba de los compuestos bis-fluorof贸ricos, para asegurar la presencia de iones met谩licos en el agua y se mostr贸 que el agua que contiene compuestos fluorescentes y en presencia de estos compuestos bis-fluorof贸ricos hay un abatimiento de la fluorescencia. El an谩lisis bacteriano mostr贸 que el 煤ltimo punto de la ciudad, cerca de la frontera de USA y M茅xico, se concentra una cantidad elevada de bacterias y que la descarga va directo al oc茅ano pac铆fico, siendo un problema de salud y ambiental