Removal of Heavy Metals Using Adsorption Processes Subject to an External Magnetic Field

Adsorption is a broadly used process for the removal of heavy metals and the world trend is directed to the application of new technologies to intensify existing processes. The properties of the magnetic field (intensity and arrangement) and the intrinsic magnetic properties of the adsorbent and the adsorbate are decisive for satisfactory results. The intensity of the magnetic field is important, because this implies that the greater number of spins present will align with the magnetic field according to the magnetic nature present, allowing the mobility of the adsorbate and generating heterogeneity on the surface of the adsorbent. Similarly, the arrangement of the magnetic field will determine the direction of the magnetic field lines. The application of a magnetic field as an alternative for the intensification of the adsorption process based on the consideration that the magnetic field is safe, environmentally friendly and economic

EL PROCESO DE ENSEÑANZA-APRENDIZAJE DE LA PRÁCTICA DE CAMPO EN LA FORMACIÓN INICIAL DEL PROFESOR DE BIOLOGÍA

The Practice of Field is recognized in the study of the specialty of Biology, for the importance that represents in the preparation of the professors in initial formation, in her, the principle theory settles down - practice with the characteristics of the nature and the society. This investigation responds to the necessity of perfecting the process of teaching-learning of the Practical discipline of Field and he/she has as objective: to propose a didactic conception with focus ecosistémico and integrative of confrontation to the climatic change, and in function of the local development that allows a bigger development of the intellectual and practical abilities, in the basic formation and the students' professional in the career Degree in Education Biology of the University of Guantánamo. For the development of the investigation methods of summary of information were used and of prosecution of these. As a result lacks like insufficient conception of a focus ecosistémico were obtained, integrative and of confrontation to the climatic change, the absence of a basic bibliography that facilitates the students to acquire intellectual and practical abilities, in correspondence with the demands of the different programs that compose the discipline, insufficient didactic and methodological precisions of the program of the Discipline of Practice of Field to incorporate the biological culture that demands the confrontation to the climatic change and the local development. The valuation carried out by the experts before the setting in practice of the proposal facilitated, to recommend this didactic conception as a valid option to be able to develop new qualities in the process of the professor's of Biology initial formation. Their implementation in the course 2018-2019, it demonstrated the effectiveness of the same one. Key words: didactic conception – ecosystemic approach – field practice – initial training – local developmentLa Práctica de Campo es reconocida en el estudio de la especialidad de Biología, por la importancia que representa en la preparación de los profesores en formación inicial, en ella, se establece el principio teoría – práctica con las características de la naturaleza y la sociedad. Esta investigación responde a la necesidad de perfeccionar el proceso de enseñanza-aprendizaje de la disciplina Práctica de Campo y tiene como objetivo: proponer una concepción didáctica con enfoque ecosistémico e integrador de enfrentamiento al cambio climático, y en función del desarrollo local, que permita un mayor desarrollo de las habilidades intelectuales y prácticas, en la formación básica y profesional de los estudiantes en la carrera Licenciatura en Educación. Biología de la Universidad de Guantánamo. Para el desarrollo de la investigación se emplearon métodos de recopilación de información y de procesamiento de estas. Como resultado se obtuvieron carencias como insuficiente concepción de un enfoque ecosistémico, integrador de enfrentamiento al cambio climático y en función del desarrollo local, la ausencia de una bibliografía básica que facilite a los estudiantes adquirir habilidades intelectuales y prácticas, en correspondencia con las exigencias de los diferentes programas que componen la disciplina, insuficientes precisiones didácticas y metodológicas del programa de la Disciplina de Práctica de Campo para incorporar la cultura biológica que demanda el enfrentamiento al cambio climático y el desarrollo local. La valoración realizada por los expertos antes de la puesta en práctica de la propuesta posibilitó, recomendar dicha concepción didáctica como una opción válida para lograr desarrollar nuevas cualidades en el proceso de formación inicial del profesor de Biología. Su implementación en el curso 2018-2019, demostró la eficacia de la concepción. Palabras clave: concepción didáctica – desarrollo local – enfoque ecosistémico – formación inicial – Práctica de Camp

Adsorción en continuo del colorante ab25 y el metal cadmio en soluciones binarias sobre carbón modificado

Abstract: The variety of contaminants in industrial waste represents a challenge for separation processes; because they usually remove one or a similar group of pollutants. The aim of this work is to characterize a modified activated carbon has the capability to remove both dye (AB25) and heavy metals (cadmium) in continuous systems; and observe null, synergistic or antagonistic effects. In this study it was observed that the dye AB25 promotes synergistic effects in removing cadmium, since for 5 and 25 mg/L Cd2+ its adsorption capacity increases from 1.7 to 22.8 and from 2.8 to 27.9 mg/g respectively when the AB25 is present in the solution. This effect depends mainly on concentrations of contaminants in the feed. The increase in metal removal is because the dye to be adsorbed by the activated carbon becomes another active site; electrostatic interactions exist between the dye and cadmium.Resumen: La variedad de contaminantes presentes en los residuos industriales representan un reto para los procesos de separación debido a que éstos comúnmente remueven uno o un grupo parecido de contaminantes. El objetivo de este trabajo es modificar un carbón activado para que tenga la capacidad de remover tanto colorante azul ácido 25 (AB25 por sus siglas en inglés), como un metal pesado (cadmio) en sistema continuo; así como observar los posibles efectos de no interacción, sinérgicos o antagónicos presentes durante el proceso de adsorción. En este estudio se observó que el colorante AB25 promueve efectos sinérgicos en la remoción de Cd2+, ya que para 5 y 25 mg/L la adsorción incrementa de 1.7 a 22.8 mg/g y de 2.8 a 27.9 mg/g respectivamente cuando el AB25 se encuentra en la solución. Este efecto depende principalmente de las concentraciones de alimentación de los contaminantes. El incremento en la remoción del metal se debe a que el colorante al ser adsorbido por el carbón activado se convierte en otro sitio activo; existiendo interacciones electrostáticas entre el colorante y el cadmio

Comercio Internacional

ExportacionesRetos que Enfrentan las Artesanías Mexicanas en la Exportación y Perspectivas de Solución: Caso del Olinal

Recovery of different types of hydroxyapatite by precipitation of phosphates of wastewater from anodizing industry

Recovery of phosphates from an anodizing industry wastewater was studied by chemical precipitation. Samples of wastewater were selected attending to the highest phosphate concentration observed during 1 year of weekly sampling. Different types of precipitant agents were analyzed in batch systems. Results showed that it is possible to remove 100 % of phosphates when Ca(OH) is used as precipitant agent. The best conditions of precipitation were found following a L orthogonal array design of the Taguchi method. For an initial concentration of phosphates of 4336 mg/L, these best conditions were a Ca/P molar ratio of 5.77, pH 2, stirring time of 15 min and settling time of 1 h. Additionally, it was demonstrated that the factors with more influence in the precipitation of phosphates with Ca(OH) were the pH of the wastewater and the stirring time. When the phosphate removal was performed at pH 6 and 10, hydroxyapatite Ca(PO)(OH) was found in the precipitate, whereas other crystalline hydroxyapatite with a more complex structure (CaNa)(CaNa)(PO)(CO)(OH) was identified in the experiment performed at pH 2. The present study provides valuable information to recover phosphate from industrial effluents.This work was supported by TecNM (project 7009.19-P) and Principado de Asturias–FICYT-FEDER (Project PCTI-Asturias IDI/2018/000118). M.C. Delgadillo-Velasco acknowledges the grant (467325) received from CONACyT

Adsorption of impurities from nickel-plating baths using commercial sorbents to reduce wastewater discharges

The presence of moderate concentrations of impurities in the nickel-plating baths generates failures on the coated pieces. This situation entails the necessity of replacing the electroplating bath, which implies the generation of large volumes of wastewater with metallic species and high quantity of sludge. For this reason, the adsorption of the principal impurities of nickel-plating baths of an industry was analyzed in this work. Particularly, the removal of Zn2+ was studied in more detail since the presence of this metal in the baths generates black spots on the coated pieces. Different commercial materials were used as adsorbents and Zn2+ adsorption studies were carried out using both standard solutions and industrial water from the nickel-plating baths. All the adsorption tests were performed in batch systems under constant agitation and the quantification of the impurities was made by ICP-MS analysis. The bone char (BC) was an efficient adsorbent for the removal of the principal impurities of nickel-plating baths. The use of molecular simulation tools helped to understand the preferences of the hydroxyapatite (the principal component of bone char) for different metallic ions present in the industrial waters. According to both the experimental adsorption and molecular simulation results, hydroxyl and phosphate groups of bone char are responsible of the adsorption of impurities of nickel-plating baths.This work was supported by TECNM (7949.20-P), Ministerio de Economía, Industria y Competitividad, Spain (CTQ 2017-87820-R) and PCTI-Asturias/ FEDER, Spain, EU (IDI/2018/000118) projects. MC. Pérez-Jiménez acknowledges the grant (857757) received from CONACyT. L.A. Ramírez-Montoya thanks CONACyT for a post-doctoral grant (CVU No 330625, 2017).Peer reviewe