Jackson Araújo de Oliveira

Modeling and simulation of breakthrough curves during purification of two chitosanases from Metarhizium anisopliae using ion-exchange with expanded bed adsorption chromatography

A mathematical model was developed to predict breakthrough curves during purification of the two chitosanases from Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid and using Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experiments were performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separation processes, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydrate chitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIV and antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an average high degree of fit (94.68%) between simulated and experimental data obtained in this work.

Estudio del Secado de Anacardo (Anacardium occidentale L.) mediante Secador Solar de Radiación Directa

In this work solar drying tests with direct radiation and its mathematical modeling to evaluate the kinetics of cashew-nut (Anacardium occidentale L.) drying comparing their efficiency concerned to natural solar drying board are presented. The experiments were performed using fruit slices with 1 cm and 2 cm of thickness, obtaining its water content versus time. Using a direct solar radiation dryer, the drying time was lower than that of natural drying board, therefore adding value to products. Diffusivity values obtained from water sliced fruits were similar to other data available in the literature. The dried products had good organoleptic properties, aroma, color and crunchy texture.

Development of a Strategy to Monitor and Control the Oil-Water Interface Level of a Liquid-Liquid Separator for Treatment of Wastewater Using an Image-Based Detector

Abstract The objective of this work is to present the development of a strategy to monitor and control the organic solvent-water interface level on the MDIF® (a mixer-settler based on phase inversion) process. This is one of the most important variables for this equipment. However, the measurement of the organic solvent-water interface level (in line) is still a hard task. There are few sensors able to measure it in laboratory scale systems due to dimensional compatibility. In the present study, a sensor for detecting the organic solvent-water interface level was developed based on the acquisition and treatment of images obtained dynamically through a camera (webcam). In addition, a control strategy was implemented in feedback mode in order to maintain the referred interface level in a desired condition. A control and data acquisition program was built in Compaq Visual Fortran language to perform the following tasks: acquisition and treatment of images for identification of water-solvent interface; decisions and implementations of control signals; and recording of data in files. Some experimental runs in open-loop were carried out using the MDIF® and random pulse disturbances were applied on the input variable (water outlet flow). The responses of interface level permitted the process identification by transfer models. From these models, the parameters for a PID controller were tuned by direct synthesis and tests in closed-loop were performed. Preliminary results for the feedback loop demonstrated that the sensor and the control strategy developed in this work were suitable for level control.

Modeling and simulation of Bacillus cereus chitosanase activity during purification using expanded bed chromatography

A phenomenological model was used to describe sequentially the three steps (flowthrough, washing and elution) of expanded bed adsorption chromatography for recovery of chitosanases from Bacillus cereus. Additionally, a hybrid strategy for model parameter estimation was carried out using particle swarm optimization and Gauss-Newton algorithms. The model was validated with independent experimental data and the statistical criteria (χ2 and mean squared error tests) showed that the hybrid strategy was more promising than just the heuristic method. With the calibrated model, surface response methodology was applied to obtain the optimal operational conditions, and experiments were performed to confirm these results. Overall, a value of 41.08% for yield was obtained using 700 mM NaCl during elution. In summary, all approach employed in this work was relevant for maximizing the yield of the chromatographic process.

Study of model application for drying of pulp fruit in spouted bed with intermittent feeding and accumulation

ABSTRACT In the present study, we applied and improved a model to describe the behavior of a spouted bed dryer with intermittent feeding for suspension drying, considering suspension accumulation inside the device. This model is important in macroscopic heat and mass balances, represented by a system of ordinary differential balances, implemented and resolved numerically using Fortran routines, in which the influence of process variables on drying dynamics were assessed. The results obtained in modeling and mathematical simulations were compared with experimental data, indicating that the model fits the process well, based on outlet air temperature and moisture.

Enhancing the recovery and concentration of polyphenols from camu-camu (Myrciaria dubia H.B.K. McVaugh) by aqueous two-phase flotation and scale-up process

ABSTRACT In this study, polyphenols obtained from camu-camu pulp residue were recovered and concentrated from aqueous two-phase flotation (ATPF) by evaluating different operating conditions, such as solvent type, pH, ammonium sulfate concentration, flotation time, air flow, and volumetric ratio. Under optimal conditions, the polyethylene glycol 400/ammonium sulfate ATPF system showed an efficiency of 81.02% and a concentration coefficient two times higher than traditional aqueous two-phase extraction. Experiments were also carried out on a semi-pilot scale, using an apparatus with a 2.5-L working volume. The results showed that the semi-pilot system was comparable to the smaller scale system.

Mathematical modeling of the whole expanded bed adsorption process to recover and purify chitosanases from the unclarified fermentation broth of Paenibacillus ehimensis

In this study, a general rate model was applied to the entire process of expanded bed adsorption chromatography (EBAC) for the chitosanases purification protocol from unclarified fermentation broth produced by Paenibacillus ehimensis using the anionic adsorbent Streamline® DEAE. For the experiments performed using the expanded bed, a homemade column (2.6cm×30.0cm) was specially designed. The proposed model predicted the entire EBA process adequately, giving R2 values higher than 0.85 and χ2 as low as 0.351 for the elution step. Using the validated model, a 33 factorial design was used to investigate other non-tested conditions as input. It was observed that the superficial velocity during loading and washing steps, as well as the settled bed height, has a strong positive effect on the F objective function used to evaluate the production of the purified chitosanases.

Characterization and drying of caja bagasse (Spondias mombin L.) in a tray dryer using a factorial planning

The caja (Spondias mombin L.) is used in the manufacture of ice-cream, jams, pulps, beverages being also consumed in natura. One of the most important procedures in food conservation is drying, considering that most fresh fruits contain approximately 80% of water. Food drying is used to obtain two basic aspects: (1) the economic factor; in the shipping and handling of the product; (2) at the manipulation; once dried and grinded, the material is rehydrated, at desirable levels, to formulate a new product as in ice cream, jams, yoghurts and drinks and may also be added to pasta, biscuits and other industrialized products. The aim of this study was to investigate the kinetics of caja bagasse drying in a fixed-bed tray dryer, using central composite factorial planning. The following factors were evaluated: temperature (55, 65 and 75 oC), dryer inlet air velocity (3.2, 4.6 and 6.0 m.s-1) and cake thickness (0.8, 1.2 and 1.6 cm) where the response of the considered variable was caja bagasse moisture content (b.s.) and the results showed that the main effects and their interactions were significant at a 95% confidence level being the best condition obtained at temperature of 75 oC, velocity of 6.0 m.s-1 and cake thickness of 0.8 cm.

Modelado Cinético y Evaluación de Catalizadores Mo2C, Mo2N y Ni-Mo/C en la Reacción de Hidrogenación de Lactosa

Resumen El objetivo de este estudio fue evaluar los catalizadores Mo 2 C, Mo 2 N y Ni-Mo/C en la hidrogenacion catalitica de lactosa para obtencion de lactitol. Los experimentos de hidrogenacion se realizaron en autoclave agitada mecanicamente a 500 rpm, 120 °C y 68 atm, utilizando una solucion de lactosa comercial, solucion de suero de queso bruto y solucion de suero de queso tras adsorcion de proteinas y de iones cloruros. El contenido de proteinas y de iones cloruros disminuyo, mediante coagulacion con quitosana y desmineralizacion por cambio ionico, respectivamente. Ademas, se hicieron pruebas modificando el pH, en medio acido (3.5) y basico (8). El mejor rendimiento en lactitol fue del 46% con Mo 2 C a pH 8. Los resultados obtenidos en los experimentos de hidrogenacion se modelaron usando la cinetica de Langmuir-Hinshelwoold. Los resultados experimentales de concentracion de lactosa y lactitol concuerdan razonablemente bien con los previstos por el modelo. Palabras clave: modelado cinetico, catalizadores, hidrogenacion, lactosa, quitosana