Effect of Hexadecyltrimethyl-Ammonium Loaded Montmorillonite on The Cu Adsorption: Adsorption Surface Sites Involved

Na raw montmorillonite (Mt) and two organomontmorillonites (OMt) with different hexadecyltrimethylammonium bromide (HDTMABr) was used to adsorb Cu2+. TheCu2+ adsorption isotherms were performed, and Langmuir, Freundlich and SIPS mathematical models were evaluated.According to the R2 term, the experimental data were appropriately described by SIPS models for all the samples.Thermal analysis of the OMt adsorbents and their Cu2+ adsorbed products indicated that HDTMA was associated with cation exchange and Van der Waals interactions to the Mt surface. The decrease of the de-surfactant temperaturemainly for MH0.5-Cu respect to MH0.5 sample would indicate a weaker Van der Waals interactions of alkyl chains at the external surface by the Cu presence. The Cu2+ and the HDTMA entrance at the interlayer of Mt was evidenced by XRDanalysis, where the cationic exchange process occurs. The zeta potential values behavior evidenced the importance of the external surface participation in the Cu2+ adsorption mainly for OMt samples.Fil: Fernández Morantes, César. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Fernández Solarte, Alejandra María. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Fundación Universitaria Los Libertadores; ColombiaFil: Torres Sanchez, Rosa Maria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentin

Bio-adhesives from soy protein concentrate and montmorillonite: Rheological and thermal behaviour

The incorporation of different amounts of montmorillonite (MMT) to soy protein concentrate (SPC) was used to improve the performance of the bio-nano-adhesive obtained. X-Ray diffraction, rheology, thermogravimetric analysis and scanning electronic microscopy were carried out to characterize the adhesives, and dry and wet strength was used to determine the adhesion strength. In the rheological measurement, the incorporation of up to 3 wt% of MMT did not modify the consistency index values of the SPC, while an increase in the flow consistency index for higher concentrations can be observed due to a strong interaction between MMT and the protein. Besides, the flow point values increase four times with respect to the value obtained for SPC alone. The decomposition temperature of SPC increases with the addition of MMT, which provides a tortuous pathway that obstructs the diffusion of volatile products out of the bio-nano-adhesive. Further addition beyond 5 wt% led to the formation of agglomerates, as verified by SEM. Moreover, the roughness of the fractured surface of the matrix can explain the decrease of the net adhesion of the nano-particles to the SPC suspensions.Fil: Bacigalupe, Alejandro. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Fernández Solarte, Alejandra María. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Fernandez, Mariela Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Torres Sanchez, Rosa Maria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Eisenberg, Patricia. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental; Argentina. Instituto Nacional de Tecnología Industrial. Centro de Plástico; ArgentinaFil: Escobar, Mariano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentin

Bio-adhesives from soy protein concentrate and montmorillonite: Rheological and thermal behaviour

The incorporation of different amounts of montmorillonite (MMT) to soy protein concentrate (SPC) was used to improve the performance of the bio-nano-adhesive obtained. X-Ray diffraction, rheology, thermogravimetric analysis and scanning electronic microscopy were carried out to characterize the adhesives, and dry and wet strength was used to determine the adhesion strength. In the rheological measurement, the incorporation of up to 3 wt% of MMT did not modify the consistency index values of the SPC, while an increase in the flow consistency index for higher concentrations can be observed due to a strong interaction between MMT and the protein. Besides, the flow point values increase four times with respect to the value obtained for SPC alone. The decomposition temperature of SPC increases with the addition of MMT, which provides a tortuous pathway that obstructs the diffusion of volatile products out of the bio-nano-adhesive. Further addition beyond 5 wt% led to the formation of agglomerates, as verified by SEM. Moreover, the roughness of the fractured surface of the matrix can explain the decrease of the net adhesion of the nano-particles to the SPC suspensions.Centro de Tecnología de Recursos Minerales y Cerámic

Humic acid interaction with clay minerals: modification of the surface properties by calcium presence

The environmental importance of humic acid (HA) is mainly related to soil fertility, but it can also develop some human diseases by its intake as well as prevent calcium assimilation. Physicochemical characterisations of a montmorillonite (Mt) and its thermal treated product (Mt550), to which HA, Ca+2 or both were added, will help to better understand the surface behaviour of the binary or ternary systems. Calcium or HA adsorption produces a decrease of the Mt and Mt550 specific surface area (SSA). X-ray diffraction indicates calcium presence and no entrance of humic acid in the interlayer of Mt, while in the ternary systems (calcium-HA-Mt) a hindrance to the calcium entrance was observed. The opposite behaviour produces the adsorption of HA or calcium on electric charge of both samples. The mean pore diameter (MPD) for Mt increases with Ca+2 adsorption while no change was found after HA adsorption, in contrast to that found for Mt550.Centro de Tecnología de Recursos Minerales y Cerámic

Adsorption of copper from aqueous solution by nano- montmorillonites

La rápida industrialización ha generado serios problemas de contaminación, deterioro del ambiente y daños en las diferentes formas de vida, debido a que la mayoría de los efluentes industriales y mineros contienen metales pesados. En este trabajo se obtuvieron y caracterizaron organo-montmorillonitas (OMMT), con propósito de retención de Cu2+. Las isotermas de adsorción ajustadas mediante los modelos de adsorción de Langmuir (sitios homogéneos) y Freundlich (sitios heterogéneos), mostraron alta adsorción en la arcilla Montmorillonita (MMT), y esta disminuyo en las OMMT modificadas con el 50 y 100% de hexadeciltrimetilamonio bromuro (HDTMABr) respecto a la capacidad de intercambio (CIC) de la MMT. La arcilla modificada con el 50% se ajusto al modelo de Freundlich (con R2= 0,961) y la modificada con el 100% ajusto al modelo de Langmuir (con R2= 0,924), mostrando la influencia de la incorporación de HDTMABr sobre superficie de la arcilla. Además, se confirmó la adsorción de Cu2+ en la intercapa de la MMT y en la modificada con el 50% de la CIC de la MMT.Trabajo publicado en Maria dos Santos Alfonso y Rosa María Torres Sánchez (eds.). Enfoques Interdisciplinarios para la Sustentabilidad del Ambiente. Buenos Aires: Editorial Sociedad Argentina de Ciencia y Tecnología Ambiental, 2015.Centro de Tecnología de Recursos Minerales y Cerámic

Simple and rapid fabrication of Na0.5K0.5NbO3 thin films by a chelate route

Na0.5K0.5NbO3 (NKN) thin films were prepared by a chelate route which offers the advantage of a simple and rapid solution synthesis. The route is based on the use of acetoin as chelating agent. The process was optimized by investigating the effects of alkaline volatilization on film properties. While we observed no evidence of stoichiometry problems due to potassium volatilization loss during the heat treatments, thin films synthesized with insufficient sodium excess presented a potassium rich secondary phase, which has a significant influence on the ferroelectric properties. We show that the amount of spurious phase decreases with increasing Na+ concentration, in such a way that a 20 mol% Na+ excess is necessary to fully compensate the volatilization loss occurred during the heat treatment. In this way, NKN thin films annealed at 650ºC presented a well crystallized perovskite structure, no secondary phases, well-defined ferroelectric hysteresis loops (Pr ~ 9 μC/cm2, Ec ~ 45 kV/cm), and low leakage current density (2 × 10−7 A/cm2 at 80 kV/cm).Fil: Fernández Solarte, Alejandra María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Pellegri, Nora Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: de Sanctis, Oscar Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Stachiotti, Marcelo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentin

Efecto de arcilla Montmorillonita K10 como refuerzo mecánico en almidón termoplástico de yuca

A wide range of plastic products of petrochemical origin are in the market due to their good mechanical properties and low cost, however, it is of public knowledge the high negative impact that these materials are causing in the environment that end up affecting biological life in every aspect.  Thus, the search for new alternatives to replace these plastics has become of interest for both the industrial sector and scientists, so in the present work the researchers explored the initiative of obtaining biopolymer nanocomposites in the form of thin film from thermoplastic cassava starch and Montmorillonite K10 type clays, the latter being used as mechanical reinforcement of the final product. The main objective of the research was to evaluate the effect of clay insertion in the biopolymeric matrix on the mechanical properties of the thermoplastic films. The preparation of the samples was carried out by the starch gelatinization process, where the baseline formulation (BPG), also known as thermoplastic matrix, was made of glycerin (plasticizer) 30% by weight. This matrix was subsequently reinforced with three different percentages of montmorillonite K10 clay (MMT): 3%, 5% and 10%, called BPGK-3%, BPGK-5% and BPGK-10%, respectively.  Mechanical properties were measured and all thermoplastic films were observed by optical microscopy. The formulation with the best mechanical properties was BPGK-5% with maximum stress, elongation at break and Young's modulus values of: 1.9 Mpa, 34% and 15.3 Mpa, respectively, as a consequence of the distribution of the clay particles in the thermoplastic matrix.En el presente trabajo se obtuvieron películas termoplásticas de almidón yuca por medio del proceso de gelatinización del almidón. La formulación base (BPG), es decir la matriz se realizó con 30% en peso de glicerina, la cual posteriormente fue reforzada con tres porcentajes de arcilla Montmorillonia K10 diferentes (MMT): 3%, 5% y 10%, denominadas BPGK-3%, BPGK-5% y BPGK-10%, respectivamente.  Se midieron las propiedades mecánicas y se visualizó por microscopia óptica todas las películas de las cuatros formulaciones, en donde la formulación que obtuvo las mejores propiedades mecánicas fue la formulación  BPGK-5%, debido a la distribución de las partículas de la arcilla en la matriz termoplástica

Correlating Antimicrobial activity and Structure in Montmorillonite modified with Hexadecyltrimethylammonium and Silver

The relationship between antimicrobial properties and structure of montmorillonite (MMT) containing hexadecyltrimethylammonium bromide (HDTMA-Br) and silver (Ag) was determined. HDTMA was adsorbed at the clay interlayer by a cation exchange, through the positive head of the ammonium group. At higher surfactant loadings (100 and 200% cation exchange capacity (CEC); MH1 and MH2 samples, respectively) the prevalence of weak adsorption (Van der Waals forces) was observed; whereas below the clay CEC (50%, MH0.5) strong interactions predominated (cation exchange). These different interactions impacted on antimicrobial activity, increasing bactericidal capacity when the surfactant was more available to diffuse. For organo-montmorillonites (OMMT) and all samples with Ag, zeta potential pointed out electrical charge changes on the outer surface, respect to MMT. XPS analyses showed peaks attributed to clusters formation, silver oxidation, and Ag0 in MMTAg and MH0.5-Ag. The Ag0 peak was also present in MH1-Ag and MH2-Ag, the later showing an extra peak associated with AgBr. HDMTA+ and Ag adsorbed on the MMT acted synergistically against Staphylococcus aureus. This effect was less noticeable for Escherichia coli and the result was attributed to both, E. coli outer envelope which might lower the efficacy of HDMTA+ adsorbed on the MMT, and decreasing silver proportions when the surfactant loading increased. MH1-Ag presented the best bactericidal properties, showing synergistic effects against S. aureus, while maintaining activity against E. coli compared to MMT-Ag. Understanding MMT-HDMTA-Ag efficacy contributes to the design of new antimicrobial materials for potential applications in health careFil: Fernández Solarte, Alejandra María. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina. Corporacion Universitaria Minuto de Dios.; ColombiaFil: Blanco Massani, Mariana Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Molina, Vanesa Magali. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Benítez Guerrero, Mónica. Universidad de Malaga. Facultad de Ciencias; EspañaFil: Torres Sánchez, Rosa M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentin

PROF-XXI: Teaching and Learning Centers to Support the 21st Century Professor

PROF-XXI is a European-funded project whose aim is the creation of Teaching and Learning Centers (TLCs) for Latin American Higher Institutions in an effort to promote the development of competences for university professors and foster teaching innovation in onsite, but also in online and hybrid education. PROF-XXI includes a partnership of seven higher education institutions, three from European countries (Spain, France, and Portugal), and four from Latin American countries (two from Guatemala, and two from Colombia). This article presents the main results of the first part of the project, including the diagnosis of institutional practices, the state of the art of TLCs around the world, the framework on 21st century professors in Latin America, and the PROF-XXI framework

Humic acid interaction with clay minerals. Modification of the surface properties by calcium presence

The environmental importance of humic acid (HA) is mainly related to soil fertility, but it can also develop some human diseases by its intake as well as prevent calcium assimilation. Physicochemical characterisations of a montmorillonite (Mt) and its thermal treated product (Mt550), to which HA, Ca+2 or both were added, will help to better understand the surface behaviour of the binary or ternary systems. Calcium or HA adsorption produces a decrease of the Mt and Mt550 specific surface area (SSA). X-ray diffraction indicates calcium presence and no entrance of humic acid in the interlayer of Mt, while in the ternary systems (calcium-HA-Mt) a hindrance to the calcium entrance was observed. The opposite behaviour produces the adsorption of HA or calcium on electric charge of both samples. The mean pore diameter (MPD) for Mt increases with Ca+2 adsorption while no change was found after HA adsorption, in contrast to that found for Mt550.Fil: Fernández Solarte, Alejandra María. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Fernandez, Mariela Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Dos Santos Afonso, María. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Torres Sanchez, Rosa Maria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentin