Estudo da adsorção de gás etileno em filmes compósitos de quitosana/zeólita
Dissertation (Ms) 27/09/2016
Suliene Dantas do Nascimento
Brazil produces more than 43 million tons of fruit per year, 47% of which is sold as fresh fruit and only 2% is destined for export. Aiming to increase this export, it was studied the production of chitosan and zeolite films that could adsorb the ethylene liberated by the fruits, which is one of the main factors that accelerates the metabolic activity and anticipate the aging of the fruit. Biodegradable films based on chitosan, which have important characteristics such as antibacterial and antifungal, have the support function of the zeolites that are molecular sieves capable of adsorbing ethylene, delaying the ripening of the fruits, reducing the waste and can facilitate the export. Dense and porous composite matrices were developed, differing their porosity by the drying process. Zeolite and composite matrices were characterized as their texture properties using nitrogen and carbon dioxide, scanning electron microscopy (SEM), water vapor permeability (PVA), and their ethylene adsorption capacity. The zeolite presented different porosity and surface area, using adsorption of N2 at -196ºC, or with CO2 at 0ºC, due to the low diffusion of N2 in molecular sieves. SEM showed a uniform distribution of zeolite in the polymer matrix and the appearance of pores from the lyophilization procedure. The chitosan film with 93% (m m-1) of zeolite (QZ93) had a lower adsorption capacity than the film of the same concentration that was lyophilized (QZ93Lio), because of the higher porosity, this presented adsorption value similar to Regenerated zeolite 90 ° C (ZR 90). The films of pure chitosan (Qtra), chitosan with 33% zeolite (m m-1) (QZ33) and lyophilized pure chitosan (QLio) present small amounts of adsorbed ethylene compared to other materials. All materials were able to adsorb ethylene. Its application seems quite feasible since the market value for these materials is more accessible than other adsorbents used and should be studied taking into account the amount of ethylene released by the fruit to be transported, whether or not it is necessary to use the material Which adsorbs greater amounts of ethylene.
Estudo da adsorção de biomoléculas (albumina de soro bovino e lisozima) em materiais mesoporosos
Dissertation (Ms) 09/09/2016
Karina Alexandre Barros Nogueira
The adsorption of proteins on solid surfaces has application in many different fields such as biomedicine, biomolecule separation, effluent treatment. This study investigates the adsorption of two biomolecules (bovine serum albumin - BSA and lysozyme - LYS) on mesoporous materials obtained from two different sources, a layered double hydroxide and a mesoporous silica. In the first part of this study , HDL (layered double hydroxide) was synthesized through the coprecipitation method using two different types of metals, zinc (Zn-Al) and magnesium (Mg-Al). The adsorption of BSA was evaluated in batch system to check the influence of the buffer solution, the contact time and the initial concentration. Experiments fixed bed were also performed to evaluate the dynamics of adsorption of BSA in HDL as well as regeneratable material. The maximum amount of adsorbed BSA was in 50mM sodium acetate buffer at pH 4.8 (the isoelectric point of the protein) to the Mg-Al LDH and 50mM MES buffer at pH 6.7 to the Zn-Al LDH. For Langmuir and Langmuir-Freundlich models we got 338.74 mg g-1 and 346.54 mg g-1 for Zn-Al LDH and 196.12 and 197.80 mg g-1 for Mg-Al LDH respectively. The results indicate that for the double lamellar hydroxides the charge density of the Zn-Al LDH with the contributions of other interactions such as hydrogen bonding or Van der Waals interaction promotes the better adsorption in 50mM MES pH 6.7 buffer of serum albumin bovine. In the second part of the SBA-15 material was synthesized by hydrothermal method with the addition of the componente 1,3,5-trimethylbenzene (TMB) and used in adsorption of biomolecules dissolved in solutions with different concentrations of sodium chloride. The maximum amount of BSA was adsorbed in 50mM sodium acetate buffer at pH 4.8 (the isoelectric point of the protein) and the LYZ was adsorbed in 50mM Tris HCl buffer at pH 10. The Langmuir model obtained 403.63 mg.g -1 for adsorption of BSA and 677.93 mg g-1 for adsorption of LYS. For adsorption results with LYZ revealed the occurrence of precipitation due to the phenomenon of "salting-out" when there is addition of salt to the solution and thus the reduction in protein adsorption capacity of the material.
Efeito estabilizante de montmorilonita sobre antocianinas de acerola: aplicação em suco clarificado e filmes comestíveis
Dissertation (Ms) 29/08/2016
Halisson Lucas Ribeiro
Anthocyanins are the most widely distributed flavonoids in plants, being responsible for colors ranging from blue to red-orange. The anthocyanins from acerolas (Malpighia emarginata DC) are very prone to degradation upon processing and storage, resulting in changes in their characateristic red color to a yellowish or brownish color, decreasing the commercial appeal of the final products. Thus, it is important to use techniques to stabilize anthocyanins in acerola products. Anthocyanin stability may be improved by copigmentation, in which the pigment and a second compound (copigment, organic or inorganic) form molecular associations which promote color intensification and/or stabilization. The use of nanoadsorbents for copigmentation has been studied recently. Among those, the montmorillonite-type clays (MMT) should be mentioned, whose effects on anthocyanin stabilization have been reported. MMT is commonly used as a reinforcement phase for polymeric materials, improving their mechanical and barrier properties. The objective of the present study was to evaluate the anthocyanin stabilization by MMT on acerola clarified juice and edible gelatin films containing acerola juice. The MMT addition promoted complexation of anthocyanins in acerola juice, with concomitant intensification of the red color and stabilization of the color parameters as functions of pH and storage time. Mass spectrometry indicated anthocyanin adsorption by MMT. The addition of 6.4% MMT (on a gelatin weight basis) to the films resulted in 30% increasing on tensile strength and 44% decreasing on water vapor permeability. Moreover, MMT promoted reduction in color lightness (L*) and intensification in red color.
Modelagem e simulação do processo de produção de etanol a partir do suco do pedúnculo de caju, visando a otimização das condições operacionais
Dissertation (Ms) 08/08/2016
Andrea da Silva Pereira
Ethanol is the most relevant biofuel in the Brazilian market, its rising demand generates interest in using other raw materials as an alternative to sugar cane. Therefore, the main purpose of the present work is to study a mathematical model for the process of cashew apple juice alcoholic fermentation by Saccharomyces Cerevisiae, making possible to check cells, sugar and ethanol concentration profiles, to optimize reaction operation conditions interfering in the reaction for scaling up the fermenter. For this purpose, laboratory experiments data of Pinheiro (2015) were used with variations of the initial cell concentration from 3 to 10 g/L parameters were varied as follows: initial cell concentration from 3 to 10 g/L, temperature from 26 to 42 °C, initial total sugar concentration from 70 to 170 g/L and stirring speed from 80 to 800 RPM. Initially, regressions and interpolations were performed to treat data, seeking for smoothing experimental data noise and increasing the amount of data for training artificial neural networks (NNAs) and to estimate parameters. Five mathematical models were proposed: four mechanistic unstructured nonsegregated models and one hybrid model that combine NNAs and mass balances. Model 1 considers negligible the substrate consumption due to cells maintenance and that all cells are viable, using the Ghose & Tyagi’s kinetic model. Model 2 differs by the hypothesis of death and cell maintenance, Model 3 derives from Model 2 with inclusion of the temperature. Model 4 adds the influence of initial concentration of cell and agitation by the hypothesis of a stagnant film surrounding the cells of flocculant S. cerevisiae. The set of parameters was determined by damped least-squares (DLS) method proposed by Marquardt. For the hybrid model (Model 5), the specific rates are predicted by NNAs as function of instant cell and substrate concentrations, temperature and stirring speed. Simulation results were statistically assessed by residual standard deviations (RSD), modified F-test and confidence interval (CI), apart from being validated by another experiment run used neither to estimate the set of parameters nor to train NNAs. Among the models studied, it was observed that the Model 4 and 5 were the most general and suitable in the studied process. The models were optimized by the bio-inspired method of particle swarm, indicated for global searches, based on the parameters efficiency and productivity of the reaction. After that, the scale up of the process for a 14 liters reactor was performed using the P/V criteria. The productivity obtained was 6 gL-1h-1 with the following optimal conditions: initial substrate concentration of 143.2 gL-1, initial cell concentration of 6.5 gL-1, temperature of 36.5 ºC and stirring speed of 80 rpm.
Utilização de membranas de contato (hollow fiber) para extração e re-extração de ácido capróico.
Dissertation (Ms) 22/07/2016
Alexsandro Viana Freitas
Caproic acid or hexanoic acid has a wide range of applications in the pharmaceutical, chemical and food industries. The utilization of a fermentative production route has been studied as an alternative to petrochemical route, which relies on non-renewable resources. In the fermentative route, it is essential to provide a continuous caproic acid extraction from the biotic medium, because the accumulation of this acid inhibits microorganisms. In this study, the extraction and re-extraction of caproic acid by contact membranes are investigated in detail. This extraction system involves reactive and diffusive processes in two stages: i) the extraction step, where caproic acid passes through selectivity to an extraction solution (mineral oil + 3% trioctylphosphine (TOPO)); ii) the re-extraction step, where the caproic acid passes through affinity to an alkaline solution (0.5M H3BO3, pH ≥ 9.0). This type of extraction system has advantages over conventional liquid-liquid extraction of organic acids, because the membrane has hydrophobic characteristics, and acts as a physical barrier, which prevents the liquid phases dispersion. LIQUICEL two membranes are used (model 2.5 x 8.0 Extra-Flow), with surface area of 1.4 m², volume of the inner hull of 0.15 L (150 ml) and volume of the outer hull of 0.40 L (400ml). Each membrane has 800 hollow fibers of polypropylene (internal diameter 0.24 mm, length 15 cm, 0.03 mm thick wall and 0.03 mM of pore size of the membrane with 40% porosity). The mass transfer rates of membrane system were determined for different operating conditions from the effluent using a bioreactor and a pure (caproic acid diluted in water) effluents. In these experiments the caproic acid concentrations ranged between 0.1 and 2.5 g.L-1, which is a representative range for reactors operated at pH 5.5. The flow rates of the acidic and alkaline solutions ranged from 9,2 a 219,4 m.d-1. During the assays, pH, and caproic acid concentrations were monitored. The experiments using synthetic effluent showed that mass transfer rates in the extraction membranes are 9,5 g.m-2.h-1, and achieved extraction efficiency of 96%. Using the bioreactor effluent, the mass transfer rates were 3,67 g.m-2.h-1, and extraction effiency was 43%. Additionally, from these tests, it is possible to observe that the extraction rates are directly proportional to the liquid velocity in the external parts of the membranes. These results confirm that the maximum rates of extraction and re-extraction of the contact membrane system are in a feasible range to be used together with anaerobic reactors for producing caproic acid.
Obtenção de nanoamido de amêndoa de manga e sua aplicação em filmes de amido para embalagens de alimentos
Dissertation (Ms) 12/07/2016
Ana Vitoria de Oliveira
Mango processing generates tons of by-products (peels, seed coats and kernels) corresponding to 40-45 wt% of fruit, and have high potential added value. The seed kernels represents 13% of that weight, and is mainly composed of starch (50%), which can be extracted and used for food packaging or coating. Despite its appeal related to renewability and biodegradability, starch films still have limitations on their barrier and mechanical properties. Starch nanocrystals (SNC) may be incorporated as a reinforcement phase in order to improve such characteristics. The objective of this study was to develop bionanocomposite films from mango kernel starch reinforced with different contents of starch nanocrystals obtained by acid hydrolysis and ultrasonication, and to compare them with those films obtained from commercial maize starch. Starches and SNC were submitted to chemical, morphological, and thermal characterizations. The films were prepared with different concentrations of SNC (0-10 wt% on the starch matrix) and characterized by tensile properties, opacity and water vapor permeability (WVP). The starch extracted from kernels presented a high yield (38.5%), low levels of impurities, a reasonable amylose content (22.1%), type A crystallinity, ellipsoidal granules with an average size of 13.2 μm, and gelatinization temperature between 75.66 and 84.13° C. The SNC were stable in solution (zeta potential > 25 mV - module), with sizes around 79 nm, high-yield (31.66%), and higher thermal stability than native starch. SNC addition resulted in improved tensile strength and modulus, higher opacity, and lower elongation at break. The films presented properties comparable to those of comercial starch, with highertensile strength, modulus, and opacity.
Captura de CO2 em Zeólita Natural por Adsorção
Dissertation (Ms) 07/07/2016
Thalles Senna Diogenes
The development of separation processes for CO2 capture has been encouraged by the negative impact of the presence of CO2 on gaseous mixture. The presence of CO2 in natural gas decreases the calorific value and tends to promote corrosion of equipments. Also, after combustion, carbon dioxide emissions to the atmosphere are believed to intensify the greenhouse effect. In this context, the use of porous materials such as molecular sieves to remove CO2 by adsorption-based processes has gained relevance as a clean and economically attractive technology. The aim of this work was to evaluate the use of clinoptilolite to capture CO2 under different scenarios. The characterization was carried out by XRD, Adsorption of N2 at -196 °C and CO2 at 9 °C, and TGA. Single component (CO2, N2 e CH4) and binary (CO2/CH4 e CO2/N2) isotherms were obtained by manometry and gravimetry. A mathematical model using the LDF approach was applied to simulate column dynamics and PSA processes. Results have shown that clinoptilolite is a microporous material, contradicting some literature also reports pointing out mesoporosity. TGA results demonstrated structural stability up to 600 °C. The diffractogram identified the following phases: clinoptilolite, cristobalite and silicon dioxide. Compared to commercial adsorbents, the textural properties of clinoptilolite, as surface area (192 m2 g-1) and total pore volume (0.0953 cm3 g-1), seem to be unfavorable for CO2 capture. The adsorption capacities of CO2, N2 and CH4 at 25 °C and 1 bar were 1.75, 0.43 and 0.78 mmol g-1, respectively. The equilibrium isotherms also revealed low adsorption capacity when compared to commercial adsorbents (ex. zeolite 13X and activated carbons). For 1 bar and 25 °C, the selectivities were 2.70 and 4.10 to CO2 in CO2/CH4 (45 %55 %) and CO2/N2 (15 %85 %), respectively. Simulation results have shown that although the material is selective for CO2, its use in processes such as PSA is not indicated under the studied conditions mainly due to its low working capacity.
Efeito de pré-tratamentos: desidratação osmótica assistida com ultrassom e luz ultravioleta pulsada na secagem e qualidade da manga
Dissertation (Ms) 21/06/2016
Thayane Rabelo Braga
Brazil is a country that stands out in fruit production, mainly in the export of some fruits, such as mango, which is appreciated by consumers for their sensory and nutritional characteristics. However so conservation methods are used to increase the shelf life of the product and add value, such as drying, along with pre-treatments that can act in preserving nutritional quality and aid in water loss (using osmotic dehydration) to reduce the drying time. Ultrasound and pulsed ultraviolet light are technologies that can affect the composition of foods either positively or negatively. On the context, the aim of this study was to evaluate the effect of pretreatment (dehydration using ultrasound and pulsed ultraviolet light) on the drying and preservation of quality of nutrients of dehydrated mango cubes. The samples were dried in an oven at 60 ° C, separated in control samples (in natural mango), but without dehydrated sample pre-treatments and specimens were subjected to ultrasound five times and four different concentrations of osmotic solutions. For the pulsed ultraviolet light, the samples were submitted to five radiation dosages. Color parameter assessments were performed, moisture variation, solid variation, water diffusivity, time to 90% reduction of water, electrolyte leakage, enzyme activity (PPO, POD, PME and PAX), hydrogen peroxide, vitamins water soluble (B1, B2, B3, B5, B6, and C) and soluble (A, D and E), pigments (carotenoids and β-carotene), phenolics and antioxidant activity (DPPH method). The use of ultrasound and pulsed ultraviolet light was effective in the inactivation of polyphenol oxidase and ascorbate oxidase enzyme treatments used in most conditions. Using these pre-treatments the amount of hydrogen peroxide was increased, and thus the antioxidant capacity and phenolics also showed an increase for some process conditions. Vitamins B and C were degraded with the use of pre-treatments, but this degradation had a greater influence on the drying process, and therefore these technologies are set to minimize the loss of vitamins B1, B2, B3, B5 and C, as well as carotenoids β-carotene, and pigments. Other B6 vitamins A, D and E. which losses obtained with the use of sonication and p UV-radiation. For the color parameters of the samples subjected to pre-treatments on study, decreased only when compared with the sample in nature. Ultrasound and ultraviolet light does not influence the color change of the sleeve as heat treatment. Osmotic dehydration is indicated as pre-drying treatment with ultrasound, since it helps in further loss of water, as well as ultraviolet light. What are not thermal technologies which favor an increase in water diffusivity, and thus can be suitable for reducing the drying time.
Produção e imobilização da enzima α – acetolactato descarboxilase em agarose utilizando diferentes protocolos de ativação
Dissertation (Ms) 19/04/2016
Celina Maria Gentil de Farias Lemos
During the fermentation process of beer brewing, yeast cells use the nutrients found in medium to accelerate the metabolism and multiply. An important carbonyl compound present in the beer fermentation is the diacetyl because this leads to the final product an undesirable organoleptic characteristic that is the flavor of butter. The formation of this carbonyl compound is non-enzymatically, wherein the acetolactate is excreted from the cell during valine synthesis and then converted into diacetyl by oxidative decarboxylation. The formed diacetyl will be reassimilated by the cell and lowered essentially in acetoin. The enzyme α - acetolactate decarboxylase operates in the acetolactate formed converting it directly into acetoin and so the diacetyl is not formed. In the first stage of this study It has been evaluated the production of the enzyme α - acetolactate decarboxylase (ALDC) for seven strains of microorganisms which were isolated from a sewage treatment plant (Universidade Federal do Ceará – Campus Pici) and from a mangrove forest soil in regions of the state of Ceará – Brazil countryside. A satisfactory production of the enzyme of interest by the seven strains tested was observed, but the strains named I5 and J6 showed the best results of specific activity values, where average values were 1795.66 U / mg and 2043.36 U / mg respectively. Since the ALDC enzyme production occurs intracellularly it was necessary to rupture the cell with a lysozyme solution to facilitate the disruption of the cell membrane, enhanced by the effect of ultrasonic waves. Subsequently, has been evaluated the capacity of the immobilized ALDC enzyme in agarose-based media activated by different protocols glyoxyl-agarose, MANAE-agarose and MANAE-glutaraldehyde. To assess the enzymatic activity was used colorimetric and High Performance Liquid Chromatography (HPLC) methodologies, where the latter is known to be more precise and presented enzymatic activity values consistent with the results presented when used the first technique. In front of all the study carried out in this research can be concluded that the tested strains showed potential for biotechnological production of the ALDC enzyme and that once produced, showed good immobilization yields for the tested media.
Caracterização e estudo da quitosana sulfatada
Dissertation (Ms) 24/03/2016
Anaftalia Felismino Moraes
Medical devices designed to be used incontact with bloodcaninduce several biological effects in the patient, such as the thrombus formation and complement system activation.Anstrategy to avoid these adverse effects is the coating of the surfaceswithhemocompatible and not immunogenicpolymers.Thisstudy aimed to developsulfated chitosanfilms withhemocompatiblecharacteristicsfor biomedical applications. Natural and sulfated chitosan films (QN and QS, respectively) were characterized by Elemental Analysis,Infraredspectroscopy (FTIR-ATR), Proton and Carbon Nuclear Magnetic Resonance(1H e 13C-NMR), Viscometry, GelPermeation Chromatography(GPC), Scanning Electron MicroscopywithEDX(SEM/EDX), X-raydiffraction(XRD) and Thermogravimetricanalysis (TGA).Thefilms hemocompatibilitywas analyzed studyingtheglobular protein adsorption (BSA and fibrinogen), platelet adhesion, anticoagulant activity and cytotoxicity by LDH (lactate dehydrogenase).The elemental analysisdemonstrated the sulfur presence in the sulfated films. TheFTIR-ATR results confirmed the sulfation reaction, with the appearance oftwo new bandsat1206cm -1 (S = O)and794cm -1(C-S-O), assigned at sulfur group. The filmQS6 with the highest sulfation degree (GS =1.37)was selectedto perform the followinganalyzes. The1HNMRanalysisshoweddeacetylation degree (DD)of 77% and 58% for the natural andsulfatedchitosan,respectively. 13CNMRanalysis showed that chitosan was partially sulfated, obtaining 2,N-3,6,O-sulfated chitosan.The mass molecular (MM) of QN and QS were 78.093 Daand 5.050 Da,respectively, determined by viscometry.Homogeneous andsmooth surfaceswere observedby SEM/EDX images. TheXRDshowedsemi-crystallinepeaks fornaturalchitosan, while an amorphous structure was observedfor sulfatedchitosan.TheTGA analysesrevealeda reduction in the thermal stability to sulfatedchitosan comparedto natural chitosan.The hemocompatibility results showed that chemical modification on chitosan chain was able todecrease the BSA (36.8%) and fibrinogen (20%) adsorption and mainly the platelet adhesion (93.7%) in relation to QN, either by SEM and optical microscopy images.Only the QS presentedanticoagulant activity in the intrinsic pathway (72.15s, 200µg/mL) compared with the QN (26.57s, 200µg/mL).It was also observed atoxicity of thestudied polymers. Theseresults indicate that sulfated chitosan films have hemocompatibility properties promising to blood-materials devices.
Modelagem e simulação do processo de secagem convectiva utilizando modelo diferencial difusivo-convectivo resolvido pelo método numérico dos volumes finitos
Dissertation (Ms) 22/03/2016
Madson Linhares Magalhaes
The consumption of energy is a main factor that determines the viability of any industrial process. Thermal dehydration is responsible for a high consumption of energy. In developed countries, 9 to 25% of the energy consumption of the national industry is attached to thermal dehydration. Thus, studying the dehydration process shows itself very promisor. In biological products, dehydration has a specific importance, the product conservation. The organic matter of the product and its water create a propitious medium for microorganisms proliferation that will deteriorate the product, making the product inappropriate for consumption. In this work, the modeling and simulation of a convective dehydration process using a diffusive-convective differential model solved by the finite volumes numeric method for predicting the behavior of the mean moisture content during the dehydration, defining molecular mass transfer and convective coefficients, and drawing moisture profiles of the interior of the solid. To evaluate the influence of internal and external resistances, the mass transfer Biot number was obtained. The implementation of the models of this work were made in Python® using its scientific models for solving differential equations. This tool has been utilized because it is open source, has simple implementation when compared to other programming languages and has performance when performing simulations. As study of cases, experimental data of assisted convective dehydration by ultrasound of apple (Malus domestica L. var Royal Gala) cubes with 8 mm under the following operation conditions: 1, 2, 3 and 5 m/s for dehydration velocities, air flow temperature of 45ºC and 60ºC, presence and absence of ultrasound during the dehydration process and presence and absence of the pre-treatment with ultrasounds. The apple cubes of the experiments have 25 ±1g of mass. The dehydration has been performed until the removal of 80% of the initial mass of the cubes. The parameters, diffusivity and mass transfer coefficient, have been adjusted by Levenberg-Marquardt non-linear regression method. The results obtained in the simulations showed that the implemented model is very promisor, because it represents accurately the process. The values for diffusivity and mass transfer coefficient herein obtained were plausible. The influence of the air flow velocity, temperature and ultrasounds assistance and ultrasounds pre-treatments have been analyzed.
Estudos de pré-tratamentos do bagaço de caju utilizando líquido iônico prótico visando a obtenção de produtos de valor agregado.
Dissertation (Ms) 18/03/2016
Carla Luzia Borges Reis
Lignocellulosic materials represent a promising renewable feedstock for the production of fermentable sugars and biofuels. Cashew apple bagasse (CAB) waste of the cashew apple agribusiness is an example of lignocellulosic material, mainly composed of cellulose, hemicellulose and lignin, which form a complex and intricate structure, and these features one of the greatest difficulties for the use of lignocellulosic residues by biotransformation, both microbial and enzyme, thereby limiting the use and prevents the conversion economically feasible value-added products. Different pretreatments of CAB were evaluated using diluted sulfuric acid, sodium hydroxide, alkaline hydrogen peroxide, to modify its structure, and among alternative technologies to pretreatment, which is gaining focus is on ionic liquids application. In this context, the present study aims to evaluate different procedures of pretreatment of CAB using the protic ionic liquid 2-(hydroxy) ethylammonium acetate (2- HEAA). Initially, the ionic liquid was synthesized for neutralization acid-base reaction using acetic acid and monoethanolamine in the 1:1 ratio at 35 °C for 24 h. Five methodologies of pretreatment from CAB were evaluated: A method - the pretreatment was conducted in a oven at 120 °C for 3 h using 5% (w/w) solid; B method - the pretreatment was conducted in a oven at 130 °C for 24 h, using 8.68% (w/w) solid, after complete dissolution ethanol 96% was added; C method - the pretreatment was conducted in a autoclave at 120 °C for 3 h, using 15.23% (w/w) solid; D and E methods - the pretreatment was conducted for heated at 80 °C for 6 h or 24 (D and E methods, respectively) using 10% (w/w) solid under continuous stirring in a reactor, after complete dissolution, was treated with a 3% (w/w) NaOH. The analysis of 13C NMR CP/MAS indicate the solids formation with crystalline cellulose structure after pre-treatment, each method has a different mechanism of action on the structure of bagasse, but there was no relationship of crystallinity in the digestibility of cellulose. All studied methods showed an increase in the digestibility of cellulose and high yield of glucose. The digestibility of the cellulose CAB after pretreatment for the methods A, B, C, D and E was 60.65%, 98%, 73.10%, 88.59% and 94.88%, respectively. Glucose yield 270 mgglucose/gCAB-IL (CAB-IL-A), 747.72 mgglucose/gCAB-IL (CAB-IL-B), 541.84 mgglucose/gCABIL (CAB-IL-C), 626.43 mgglucose/gCAB-IL (CAB-IL-D), 720.92 mgglucose/gCAB-IL(CAB-IL-E), while the CAB reported 48 mgglucose/gCAB at 96 h of enzymatic hydrolysis. The results demonstrated that increasing crystallinity is a factor of the second order in enzymatic hydrolysis and decreasing the lignin percentage in that the samples positively affects the hydrolysis, taking the 2-HEAA the percent delignification of up to 91.54% (CAB-IL-E), also shown in the FTIR spectra. The pretreatment that was more satisfactory was the method B, that showed a higher level of remaining solids, high digestibility (97.80%), high yield glucose 747.72 mgglucose/gCAB-IL and 8.68% (w/w) of CAB/IL. The potential of reuse of the IL was examined using the method B, the IL was used in three pre-treatment processes (once pure and two times reused), which resulted glucose yield of 463.09 mgglucose/gCAB-IL (CA-IL-R-1) and 505.04 mgglucose/gCAB-IL (CAB-IL-R-2) at 72 h of enzymatic hydrolysis. This work appears as innovative and important model for advancing the use of ILs protic in the pretreatment of CAB, presenting a promising alternative that results in high extraction of lignin from CAB and in high yields in the enzymatic hydrolysis, which may then serve as substrates for the production of value added products.
Produção da enzima xilose redutase por candida tropicalis atcc 750 usando hidrolisado hemicelulósico do bagaço de caju
Dissertation (Ms) 15/03/2016
Juliana de Franca Serpa
Xylose reductase enzyme (EC 184.108.40.206) has potential application in the production of xylitol, and is an intracellular enzyme commonly found in yeast. Xylitol is a carbohydrate-alcohol used in food, dental, pharmaceutical and cosmetic industries. The large-scale production of this enzyme, as well as its industrial application for the production of xylitol and other bioproducts, has been limited due to the high price of commercial xylose. This problem has motivated researchers to develop better techniques for reducing the costs of obtaining XR, for example, the search for new raw material and the process conditions. Among possible feedstocks, lignocellulosic materials, as cashew apple bagasse, are low cost sources with potential applications in bioprocesses. In this context, the aim of this study was to evaluate the production of xylose reductase enzyme (XR) and xylitol by biotechnological processes by the yeast Candida tropicalis ATCC750 and hemicellulose hydrolysate from cashew apple bagasse (CAB) as substrate. The hemicellulose hydrolysate from cashew apple bagasse (HBCD) was obtained by acid hydrolysis with diluted sulfuric acid (H2SO4) and it used as a culture medium. The processes were conducted in orbital shaker at 150 rpm and different temperatures (25 °C, 30 °C, 35 °C and 45 °C). The xylose reductase enzyme extracts were used to reduce xylose to xylitol and the XR activity was determined by NADPH oxidation reaction at 25 °C. According to the analyzed data using hemicellulose hydrolysate (HBCD) medium, the highest microbial growth was observed at 25 °C and 30 °C and slightly growth at 40 °C. Under the experimental conditions evaluated, the production of xylitol was not observed, but there were the production of xylose reductase enzyme and ethanol. The XR from Candida tropicalis resulted in a crude extract with a higher enzymatic activity in the temperature of production at 25 °C (0.265 U/mL). In the partial characterization of the enzyme, the optimum pH and temperature were 7.0 and 50 °C, respectively. Subsequently, the gel electrophoresis was performed under denaturing conditions for identification of the enzyme fractions, which identify a heterodimeric structure with a molecular weight of approximately 30 kDa. The results showed that the cashew apple bagasse hydrolysate did not favor the xylitol production in the studied conditions; however, it is a potential means for biotechnological production of the enzyme xylose reductase (XR).
Desenvolvimento de materiais híbridos à base de celulose bacteriana e/ou hidroxiapatita dopados com estrôncio
Dissertation (Ms) 03/03/2016
Erika Patricia Chagas Gomes
Hybrid materials are widely used due to it's their unique properties that have provided advance in science. The hybrid produced with the combination of bacterial cellulose (BC) and hydroxyapatite (CaHA) has been shown to be a promising material, especially for bone repair. The insertion of strontium (Sr) in CB/CaHA matrices was chosen due to its similar properties to calcium, with a similar action in the human body related to the bone formation mechanisms. In this context, this study aims to obtain hybrid materials containing bacterial cellulose and/or hydroxyapatite doped with strontium ions, using three different synthesis routes. The first route is the formation of a hybrid material CB/HA, where hydroxyapatite is formed by calcium phosphate (CaHA), followed by batch adsorption of Sr ions, generating the hybrid (CB/CaHA/Sr). In the second route synthesis the hybrid is formed using apatite strontium (SrAp), by CB immersion cycles on dibasic sodium phosphate solution and strontium chloride solution, forming the hybrid (CB/SrAp). The synthesis third route consists of strontium insertion into the culture medium, which leads the formation of a hybrid CB/Sr by co- condensation. The three biomaterials produced were evaluated and compared, related to the amount of metal adsorbed and to the elution process. The higher amount of Sr adsorbed in the biomaterials for each route was in the following order: CB/SrAp > CB/CaHA/Sr > CB/Sr, 237,31; 29,91; 26,25 mg of Sr per g material, respectively. The CB/CaHA/Sr presented the lowest adsorbed amount and earler Sr release, with around 80% of Sr desorbed after 26h. The equilibrium adsorption data were described using the Langmuir model. Some parameters were investigated (temperature and pH) in the adsorption process. The Sr release by the other two materials (CB/Sr and CB/SrAp) were around 50% and 16% of the total Sr amount after 26 h, respectively. During production of CB/Sr it was observed that when compared to a BC control sample (produced without the addition of strontium) in the culture medium, there was a yield loss in terms of cellulose mass, suggesting that Sr causes a decrease in production of CB, it is corroborated by the decrease in sugar consumption by the bacteria. The materials were characterized through FTIR, SEM, BET, TGA, determination of porosity and swelling degree in order to elucidate the morphology and the interaction metal/biopolimer. From these results we can concluded that biomaterials produced are able to adsorb/desorb Sr ions, showing a different profile for each material, involving either chemisorption and physisorption mechanisms.
Propriedades catalíticas de nanotubos de titanatos aplicados na reforma seca do metano
Dissertation (Ms) 02/03/2016
Davi Coelho de Carvalho
Dry reforming of methane reaction was conducted in the presence of titanate nanotubes (TNTs) modified with Co, Ni and Pt. TNTs were synthesized by hydrothermal treatment and than these solids were either submitted to ion exchange for Ni and Co using hexahydrate nitrate solutions, or they were submitted to wet impregnation with H2Ptl6.6H2O (1% w/w of Pt) solution. The solids were characterized before and after the dry reforming of methane by elemental chemical analysis (CHN), X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption-desorption isotherms, thermoprogrammed reduction (TPR), CO2 thermoprogrammed desorption (CO2-TPD), transmission electronic microscopy (TEM), scanning electronic microscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). Raman and XRD results showed the presence of Na2Ti3O7 phase to all sodic nanotubes, while that the nanotubes modified displayed peaks and vibrational modes relative to CoTi3O7, NiTi3O7 and PtOx/Na2Ti3O7 phases. TEM images exhibited tubular morphology composed by multi-walls, as observed by XRD and Raman. SEM-EDS results showed the nanotubes composition with M/Ti ratio lower than the theoretical (value of 0,33), due to the presence of structural water. The XPS results confirmed the presence of M(OH)2 phase (M=Co, Ni or Pt) present on nanotubes surface. TPR patterns suggested the formation of M0/MTiO3 (M = Co, Ni and Pt) after the reduction of the nanotubes at 650 ºC. The nitrogen adsorption-desorption isotherms of sodic and modified TNTs showed isotherms type IV with an essentially mesoporous structure. CO2-TPD patterns suggested the presence of weak and moderate basic sites in all catalysts, indicating phase transformation due to the decomposition, in situ, of as-prepared nanotubes. The catalyst NiTNT exhibited the highest CO2 and methane conversion at 600 ºC, with about 43 and 25%, respectively, and H2/CO ratio equal 1, without deactivation over time. PtTNT was lesser susceptible to coking, although sintering remarkably decreased the performance of this solid. On the other hand, PtTNT and CoTNT showed formation of coke over the PtOx/PtTiO3 and Co0/CoTiO3 active phase, respectively, so that the latter solid deactivated during the dry reforming of methane.
Estudo da densidade, viscosidade e velocidade do som de sistemas contendo Biodiesel, diesel e Óleo
Dissertation (Ms) 26/02/2016
Victor Morel Nogueira
The scarcity of fossil fuels and the increase of environmental problems, such as greenhouse effect and the global climate change, reinforce the attention to alternative energy sources. In this context, biodiesel shows an excellent alternative for the replacement of petroleum diesel due to some interesting properties, such as non-toxicity, biodegradability, better lubrificant, complete miscibility in petroleum diesel and good usage in a diesel engine with no significant modifications in the engine. Brazil is among the top three world producers of biodiesel, mainly due to the wide variety of climatic conditions, soil conditions and biodiversity, making the environment conducive to the production of oil that are used for the production of biodiesel. Today, the diesel fuel sold in the country has 7% (v / v) of biodiesel in its composition. In this context, the accurate determination of physical and chemical properties such as density (ρ) and dynamic viscosity (��) is important to the design of diesel engines and to the design and operation of biodiesel plants. In the same way, the speed of sound (u) is one important acoustic property that affects directly the fuel injection characteristics and the amount of NOx emissions. Furthermore, this property also permits the estimation of other thermodynamics properties such as isentropic/isothermal compressibilities (kS, kT), isobaric/isocoric heat capacity (cp, cv), Joule- Thompson coefficient (ȠJT), isobaric thermal expansion coefficient (αp) and bulk modulus (β).This work presents experimental data of density, viscosity and speed of sound of binary systems containing oil, biodiesel and petroleum diesel. Speed of sound and density data were adjusted according to an equation showing a curvilinear behavior with mole fraction and a linear behavior with temperature and viscosity data were adjusted to an equation with temperature (T) and mass fraction (w) as independent variables with an exponential dependence of the inverse of temperature and proportional dependence with mass fraction. In addition, some predictive methods for estimating the three properties listed above were analyzed. Furthermore, the isentropic compressibility (kS), the bulk modulus (β) and the isobaric expansivity were derived from the experimental data for density and speed of sound.
Uso de bagaço de caju como suporte para a imobilização de lipase do tipo b de candida antarctica: aplicação na síntese de r-indanol
Dissertation (Ms) 25/02/2016
Ticiane Cavalcante de Souza
The cashew apple bagasse (CAB), an agroindustrial wastes, was used as a support for the immobilizing of lipase kind B de Candida antarctica (CALB). After treatment with alkaline hydrogen peroxide (AHP), CAB-AHP was functionalized with glycidol (GLY), epichlorohydrin (EPI), glycidol – ethylenediamine- glutaraldehyde (GEG) 5% and 10% and then, characterized through analysis of the Scanning Electron microscopy (MEV) and Red Infra Fourier Transform (FTIR). The biocatalysts produced at pH 10 (25 mM, 25 °C, 0.5% Triton® X-100) and at pH 7 (5 mM, 100 mM, 25 °C, 0.5% Triton® X- 100), were characterized with respect to thermal stability, stability in the presence of organic solvents, pH relationship and hydrolytic activity. The derivatives were applied in the enzymatic kinetic resolution of rac-acetate indanila (30 °C, 24h, 250 rpm). The biocatalyst produced at pH 10.0, CAB-GLI and CAB-EPI showed high swelling and low catalytic activity (0.22 ± 0.19 U/g and 0.21 ± 0.22 U/g) respectively. The CABGEG 5%, in the presence and in the absence of 0.5% Triton® X-100, showed high catalytic activities (21.8 ± 0.52 U/g 38.8 ± 0.37 U/g) and high immobilization yields (95.1% and 97.1%), respectively. The longest times of half-life t1/2 were obtained under assay conditions at 60 °C and pH 5.0, 32.9 minutes for the immobilized prepared in the absence of Triton® X-100 and 29.8 minutes with addition of detergent. The stability in the presence of tetrahydrofuran solvent (THF) was best achieved when the derivative was prepared with addition of 0.5% Triton® X-100, showing t1/2 of 60 minutes. For the derivatives produced at pH 7.0, CAB- GEG 10% (5 mM) in the presence of detergent showed enzymatic activity of 29.62 ± 0 74 U/g. This derivative showed the best immobilization parameters in assays at pH 7.0. The most stable derivative at 60 °C showed t1/2 of 100.7 minutes (CAB- GEG 10%, 5 mM at pH 5.0). For the stabilities to organic solvents in the presence of tetrahydrofuran, the biocatalyst obtained in higher ionic strength conditions (100 mM) and in the presence of detergent was the most stable, t1/2 129.7 minutes. The derivatives were applied in the enzymatic kinetic resolution of rac-acetate indanol, showing high conversion values (50%). They can be applied in the production of intermediates used in drug formulations, such as Rasagiline Mesylate, indicated for the management of Parkinson's disease.
Estudo de imobilização da lipase do tipo B de Candida antarctica em silicato mesoporoso nanoestruturado (SBA‑15) visando a aplicação em reações de elevado interesse industrial
Dissertation (Ms) 24/02/2016
Nathalia Saraiva Rios
A recombinant Candida antarctica lipase B expressed in Pichia pastoris by insertion of an external DNA (LIPB) was immobilized in nanostructured mesoporous silicas of SBA-15 type by physical adsorption (SBA-15-LIPB) and covalent attachment (SBA-15- APTES-GA-LIPB e SBA-15-APTES-DVS-LIPB). Influence of contact time enzymesupport and the medium pH were evaluated to the production of biocatalysts. The thermal stability of immobilized enzymes were evaluated and the results showed that the SBA-15-APTES-GA-LIPB has the best thermal stability with t1/2 = 36,91 min while the SBA-15-APTES-DVS-LIPB has t1/2= 11,83 min and the SBA-15-LIPB has t1/2= 8,5 min, at 50 ºC. However, the SBA-15-LIPB has high stability in organic solvents than the biocatalysts produced by covalent attachment. Therefore, the biocatalyst SBA-15- LIPB (Optimized conditions: 100 % of the recovery activity an 1 hour of contact time, pH 7) was applied in a model esterification reaction in the short chain esters synthesis, the methyl and ethyl butyrate. The results showed that in optimized conditions of esterification (temperature: 37 ᵒC, solvent type: hexane for the methyl butyrate and isooctane for ethyl butyrate synthesis, substrate concentration: 0,2 mol/L, molar ratio of substrates 1:1, time of reaction: 12 h) the conversions were: 79.25 % for the methyl butyrate synthesis and 86.52 % for ethyl butyrate synthesis. The biocatalyst SBA-15- LIPB exhibited high activity and operational stability on the methyl and ethyl butyrate synthesis by esterification after five and six successive cycles of 12 h each, respectively. The biocatalysts SBA-15-APTES-GA-LIPB and SBA-15-APTES-DVS-LIPB were applied in a model hydrolysis reaction in the kinetic resolution of the phenylethyl acetate. The experimental data showed that were obtained positive results for both biocatalysts, but the biocatalyst SBA-15-APTES-GA-LIPB was more efficient, producing enantiomeric excess 99 %, conversion 50 % and enantiomeric ratio 1057.
Produção de biossurfactante por aureobasidium thailandense utilizando resíduos agroindustriais
Dissertation (Ms) 22/02/2016
Dayana Pinto de Meneses
Biosurfactants are natural amphipathic molecules thus they can reduce the surface and interfacial tensions. They are produced by a variety of microorganisms, mostly by bacteria and yeasts. The aim of this study was to evaluate the biosurfactant production from the submerged fermentation process by Aureobasidium thailandense, isolated from Cashew stalk (Anacardium occidentale L.) using organic residues as carbon and nitrogen source. The first experiments were conducted in order to select the sources of nutrients from the following sources: molasses, waste water from the production of olive oil (olive mill wastewater - OMW), glucose, yeast extract and corn steep liquor (CSL). The study conducted using a fractional factorial 23-1 to analyze the effect of nitrogen sources (yeast extract and corn steep liquor) and olive mill wastewater concentrations in the medium. CSL obtained negative effect on the production of the biosurfactant. A central composite rotated design (CCRD - 22) including 4 trials in the axial conditions and three repetitions at the central point, was performed to optimize the yeast extract and olive mill wastewater concentration. The real values obtained from fermentation using the concentrations of 2 g/L of yeast extract, 1.5% (v/v) of OMW, 6 g/L of glucose and 1 g/L of KH2PO4 were 27 ± 2 5 mN/m and 28 ± 2.6 mN/m at 24 and 48 h, respectively. The maximum reduction in surface tension values of the fermentation broth generated were estimated at 27 mN/m (24 hours) and 28.2 mN/m (48 hours).The biosurfactant produced by A. thailandense showed a critical micelar concentration (CMC) of 550 mg/L, reducing the water surface tension from 72 ± 0.8 mN/m to 33 mN/m. The structure of the molecule represents CH3 – (CH2)10 –, where its ester portion has not yet been identified. The emulsifying ability was verified comparing the produced surfactant against the synthetic surfactant SDS (E24 = 57 ± 0.57%) at 10 mg/mL. It was obtained a E24 = 49 ± 0.4%. The surfactant produced by A. thailandense caused a 86% dispersion of crude oil in plate and its action after 24 hours remained stable, SDS surfactant showed no dispersion in the same time interval.
Reações de malenização de óleo de mamona na presença de iniciadores de radicais livres
Dissertation (Ms) 22/02/2016
Dayanne Lara Holanda Maia
The maleate castor oil is used in drying oils, water-soluble paints, personal care products, synthetic lubricants, etc. Initially, maleate castor oil production was studied from of maleinization reaction between castor oil and maleic anhydride. Then, maleinization reactions of castor oil were carried out using benzoyl peroxide (BPO) and di-tert-butyl peroxide (DTBP) as reaction initiator to maleate castor oil production. Reactions were carried out in a batch-type reactor. The performance of the free-radical reaction was evaluated by comparing it with the reaction carried out in absence of initiator. The response surface methodology (RSM) was used to evaluate the influence of temperature and initiator concentration on castor oil conversion into maleate castor oil in the presence of BPO and DTBP. Analysis of operating conditions by RSM showed that the most significant variable the reaction was temperature, and that the initiator concentration had little significance on the conversion of castor oil. Maleate castor oil was characterized by FTIR and NMR spectroscopy. The best conversion obtained in maleinization reaction with BPO was 94.7%, at 120 °C and 176.6 °C, when initiator concentration was 0.010% in a reaction time of 180 min. The use of BPO and DTBP was most significant on increasing castor oil conversion in 30 min and 60 min reaction, respectively. After 90 min, the use of the initiator BPO and DTBP had little influence on increasing the conversion of castor oil. Besides, it was analyzed the influence of six initiators: benzoyl peroxide (BPO), di-tert-butyl peroxide (DTBP), dicumyl peroxide (DCP), tert-butyl peroxybenzoate (TBPB), sodium persulfate (PSNA) and potassium persulfate (PSK). The use of these initiators in the reaction has contributed to reduction of reaction time. The reduction was of approximately 30 min. Sodium persulfate was shown very promising in reaction at 140 °C to have reached 90% conversion in only 70 min, besides the initiator of lowest cost among the studied.