Examinando por Autor "Ontiveros Ortega, Alfonso"
Mostrando 1 - 2 de 2
- Resultados por página
- Opciones de ordenación
Ítem Adsorption of Graphene Oxide onto Synthetic Fibers: Experimental Conditions(Springer Nature, 2018-08-23) Giménez Martín, Elena; Moleón Baca, Jose Alberto; Ontiveros Ortega, Alfonso; Plaza, IvánComparative studies on the adsorption capacity of two synthetic fibers, polyamide (PA 66) and polyester (PET) pre-treated with N-cetylpyridinium chloride (PET-NCPCl), towards graphene oxide (GO) have been carried out. The fiber samples were characterized by scanning electron microscopy (FE-SEM) and Raman spectroscopy. The results of adsorption isotherms, kinetics, and zeta potential determinations as a function of the GO concentration, pH, and temperature show that at a low pH of 2.5 and a high temperature of 323 K, almost 99 % of the 75 mg/l GO solution is adsorbed onto PA 66 and 70 % onto the PET-NCPCl fibers. The interaction should be first attributed to electrostatic forces, also the adsorption data exhibited a good fit to the Freundlich isotherm model and the free energy value of 10 kJ/mol was in the range of physical adsorption, which could suggest that the interaction is driven mainly by physical forces. Due to the increasing development of wastewater treatments based on the GO reactivity with metals and cationic contaminants, synthetic fibers coated with GO could be considered an adsorbent for environmental applications.Ítem High varability of interaction energy between volcanic particles: implications for deposit stability.(Springer Nature, 2023-10-27) Ontiveros Ortega, Alfonso; Calero, Julio; Moleón Baca, Jose AlbertoLandslides on the flanks of stratovolcanoes can significantly modify the structure of the volcano. Macroscopic factors that determine the stability of volcanic deposits are well understood, but the microscopic interactions between particles and their impact on deposit cohesion remain poorly understood. Deposit cohesion is related to the energy of interaction between particles, and its calculation depends on the surficial properties of the eruptive materials. The purpose of this study was to perform a preliminary comparative analysis of the surficial properties of volcanic materials from various tectonic settings, including electrical (zeta potential) and thermodynamic (surface free energy) components and to calculate the total interaction energy between particles under different environmental conditions. We analyzed samples of eruptive materials obtained from volcanic flows characteristic of six active volcanoes (El Hierro, Pico Do Fogo, Vulcano, Stromboli, Mt. Etna, and Deception Island). The results show that deposit cohesion varies among volcanoes and changes drastically with the pH of the medium. Among the volcanic systems investigated, El Hierro (pH = 3) has the most cohesive materials, while Mt. Etna (pH = 8) has the least cohesive materials. Our results suggest that microscopic electrical and thermodynamic properties play a role in the stability of volcanic deposits, and confirm the need for a greater research focus in this area.