Florián-Algarín, Miguel Á.

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    Blend uniformity and powder phenomena inside the continuous tumble mixer using experiments and DEM simulations
    (2014) Florián-Algarín, Miguel Á.; Méndez-Román, Rafael; College of Engineering; Almodóvar, Jorge; Acevedo, Aldo; Cardona Martínez, Nelson; Department of Chemical Engineering; Romañach, Rodolfo J.
    The pharmaceutical industry is in the middle of a major transition regarding manufacturing where continuous operation is a central topic. One of these operations is powder mixing, which could arguably be the principal process in pharmaceutical drug manufacturing. Currently, this operation is performed in batch mode, with limitations such as sampling methodology, unknown process scale-up behavior, and limitations to apply control strategies. Pharmaceutical companies have been working on the implementation of continuous processes as an alternative to batch processes using the Food and Drug Administration (FDA) Process Analytical Technology (PAT) initiative. However, existing continuous mixers apply high shear to the materials causing problems in their flow properties. To solve this problem, at the pharmaceutical operations laboratory of University of Puerto Rico at Mayaguez a low shear continuous tumble mixer was developed. This mixer is based on the existent batch drum mixers and does not have screws or paddles that affect the materials properties. This study focused on mixing capabilities, and the powder phenomena inside the continuous mixer as a function of inlet flow rate, mixer rotation speed, feeding angle, and material properties using experiments and Discrete Element Method (DEM) simulations. Experimental results demonstrated that the mixer is capable of achieving good mixing levels based on the relative standard deviation of the outlet concentration. The mass hold-up and powder behavior were affected by the material properties and the operating parameters. A map of material compressibility index was developed to relate the effect of the material properties and operating conditions to the powder behavior inside the mixer. The regimes obtained were rolling, cascading, and cataracting, with the best uniformity results. The simulation results demonstrated that the main mixing mechanism is convection. Simulations also demonstrated that cohesion reduces the concentration variability due to higher mass hold-up, particle interactions, and mean residence time. Final blend uniformity was measured and a relationship with cohesion and collision frequency was found. Finally, a modification of the Froude number taking into account the effect of material properties was proposed and the flow regimes of the simulations were evaluated using this number.
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    Determinación y cuantificación de metales en agua potable y agua embotellada disponibles en Puerto Rico
    (2009) Florián-Algarín, Miguel Á.; Román-Velázquez, Félix R.; College of Agricultural Sciences; Joubert, Aidalú; Negrón, Edna; Department of Food Science and Technology; Estévez, L. Antonio
    Mediante el uso de la técnica de Inductively Coupled Plasma – Mass Spectrometry (ICPMS) y siguiendo el Método 200.8. de la Environmental Protection Agency (EPA) se determinó y cuantificó la presencia de aluminio, cobre, hierro, plomo, cadmio, arsénico, sodio, calcio, potasio y magnesio en diferentes tipos de agua. Se analizaron 32 muestras de agua potable de diferentes municipios de Puerto Rico, 20 muestras de agua Embotellada (12 de compañías locales y 8 marcas importadas) y 10 muestras de agua filtrada mediante el uso de filtros domésticos. Para la recolección y almacenamiento de muestras se estableció un protocolo que garantizó que todas recibieran el mismo tratamiento. De los resultados obtenidos se concluye que todas las muestras analizadas cumplen con los límites establecidos por las agencias reguladoras para las concentraciones de aluminio, cobre, hierro, cadmio, arsénico y plomo. Para calcio, magnesio, sodio y potasio no existen límites legales y los resultados muestran mayor variabilidad de estos minerales en el agua embotellada, obteniéndose mayores concentraciones en el agua tipo mineral. Las muestras de agua filtrada no mostraron un comportamiento constante que permita establecer su efectividad para la remoción de los metales analizados. Se realizó un análisis de varianza observando diferencias significativas al agrupar el agua potable por regiones y el agua embotellada de acuerdo al país de origen. Se estableció que las concentraciones de los metales varían de acuerdo al sitio de origen, tratamientos de purificación y tipo de agua analizada. El agua embotellada y el agua potable tienen características similares de acuerdo a la concentración de los metales analizados.