PPGM PROGRAMA DE PÓS-GRADUAÇÃO EM MATERIAIS CENTRO DE TECNOLOGIA Phone: Not available
Dissertations/Thesis

Clique aqui para acessar os arquivos diretamente da Biblioteca Digital de Teses e Dissertações da UFAL

2024
Thesis
1
  • KARLISSON ANDRE NUNES DA SILVA
  • STUDY OF MECHANICAL AND ELECTROTHERMAL PROPERTIES OF STRATIFIED CONCRETE ELEMENTS WITH FUNCTIONAL CLASSIFICATION

  • Advisor : PAULO CESAR CORREIA GOMES
  • COMMITTEE MEMBERS :
  • CAMILA DE SOUSA VIEIRA
  • CASSIA VANESSA ALBUQUERQUE DE MELO
  • KAROLINE ALVES DE MELO MORAES
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • PAULO CESAR CORREIA GOMES
  • SHEYLA KAROLINA JUSTINO MARQUES
  • WELLINSILVIO COSTA DOS SANTOS
  • Data: Mar 28, 2024


  • Show Abstract
  • The search for concrete constructive elements with functional classification, capable of adequately responding to different actions and stresses, has been the subject of research aiming at functional grading, stratification, additive manufacturing, and 3D printing as pathways for concrete elements to behave effectively, without waste, with improved competitiveness, and greater efficiency. The technique of stratification, allocating concretes in layers, is the most accessible and has been applied by several authors to achieve concrete with better performance. This research aimed to study the mechanical and electrothermal properties of stratified concrete elements with functional classification (CECF), focusing on the behavior of beam and slab elements under pure bending, and walls under electrothermal actions and aggressive agents. For this purpose, concretes with normal density (CDN) and low density, foam cellular concrete (CCE), the latter in two foam dosages (10% and 20%) referred to as CCE10 and CCE20 respectively, were produced. These concretes served as references. CECF were produced in two layers (CCE1020 and CCE20CDN) and in three layers (CCE1020CDN), factors such as specific mass, concrete position in the mold, and time of deposition between layers were determined. All concretes were produced on two different days, on the first day called 1st molding, and on the second day called Replica. Each concrete was tested for compression, tension, modulus of elasticity, pure shear, electrical resistivity, thermal conductivity, and resistance to high temperature. The compressive strength of the concretes showed values greater than 20 MPa, classifying them as structural concretes. In the four-point bending test, stratification had positive effects, resulting in practically equal or higher results compared to reference concretes. In the modulus of elasticity test, there was a reduction in values compared to CDN values; however, there was a gain compared to individual concretes CCE10 and CCE20. In the pure shear test, all stratified concretes (CCE1020, CCE20CDN, and CCE1020CDN) presented practically the same value of pure shear stress, around 5.5 MPa. In the high-temperature compression resistance test, the behavior of the concretes subjected to 200ºC and 400ºC was quite similar. The stratified concrete CE1020 showed the least variation compared to the other concretes. The electrical resistivity of stratified concretes was higher than 20 KΩ.cm, making them negligible for reinforcement corrosion development. The heat flow of the concretes was also determined, with CCE1020 concretes showing the best performance, as they are composed of concretes with lower specific mass. Overall, stratified concretes showed better performance compared to reference concretes, proving that they can bring better benefits to concrete elements.

2023
Thesis
1
  • JULIANA CRISTINA PEREIRA LIMA PAULINO
  • Evidence of Layered Double Hydroxides as adsorbent agents in aquatic matrices
  • Advisor : LUCAS MEILI
  • COMMITTEE MEMBERS :
  • ANAMALIA FERREIRA DA SILVA
  • CAMILA BRAGA DORNELAS
  • JOSEALDO TONHOLO
  • KELYANE DA SILVA
  • LUCAS MEILI
  • PATRICIA DE CARVALHO NAGLIATE
  • Data: Feb 28, 2023


  • Show Abstract
  • Human actions have affected the quality of water resources causing great impact to the environment around the world, significantly reducing their availability for consumption. Faced with the priority need to remove contaminants and pollutants in the most diverse aquatic matrices, the development of new technologies for this purpose becomes essential. Some decontamination processes employ solid materials for adsorption, providing low cost associated with high efficiency. The lamellar double hydroxides (HDLs) in addition to being versatile, show promise in adsorption processes. A Scoping Review was carried out in order to obtain a global overview of what has been studied on the use of lamellar double hydroxides as adsorbing agents for contaminants and pollutants in aquatic matrices. Data collection was performed by searching publications by three independent reviewers on online platforms (a) Web of Science (WoS); (b) Scopus; (c) Science Direct; (d) National Library of Medicine (PubMed), (e) Google Scholar and (f) Open Grey; through the use of keywords: layered double hydroxides, environment, contaminant, pollutant, aqueous medium, aqueous solution, adsorption, adsorbent and adsorbent agent. The inclusion criteria were: publications indexed in selected databases that contribute in a relevant way to the research question and open access. The chronology used was from the date of origin of each electronic platform until the year 2021. Based on the eligibility criteria, 17 studies were selected, from 14 different nationalities, with their publication period between 2005 and 2021, denoting the scientific effort of 103 researchers. The predominance of the origin of the studies was recorded, as well as the composition of the HDLs used, the contaminants, the pollutants or reaction media in which they were used, the synthesis method used and the most relevant considerations of each research. This work evidenced the main information that describes the HDLs as promising materials and of significant relevance as an adsorbent of contaminating agents and pollutants in aquatic matrices, highlighting the challenges identified for the emergence of new studies on the subject.

2
  • JONATHAS MATIAS DE OLIVEIRA
  • DIRECT LASER WRITIG MICROFABRICATION OF INTEGRATED OPTICAL DEVICES

     
     
  • Advisor : EDUARDO JORGE DA SILVA FONSECA
  • COMMITTEE MEMBERS :
  • JOSÉ FERRAZ DE MOURA NUNES FILHO
  • ANDRE DE LIMA MOURA
  • CLEBER RENATO MENDONCA
  • EDUARDO JORGE DA SILVA FONSECA
  • MARCOS VINICIUS DIAS VERMELHO
  • Data: Mar 3, 2023


  • Show Abstract
  • The three-dimensional microfabrication via direct laser writing techniques has opened a
    window of opportunities for research and technological applications in several areas such
    as optical communication, microfluidics, synthesis of new materials, 3D scaffolding for
    cell culture, construction of optical microdevices, and others. The possibility of building
    a 3D optical device directly on a substrate or inside a transparent bulk has driven research
    groups and engineers around the world to design and develop integrated micro-optical
    systems capable of manipulating light signals and making them interact with mechanical,
    electronic, fluid, chemical and biological elements. The works developed during this Phd
    represents a small but substantial contribution for this line of research. Initially, the twophoton
    polymerization technique was used to write a helical axicon, a light micromodulator
    able to convert Gaussian beams into structured beams possessing orbital
    angular momentum, whose profile is described by a superposition of high-order Bessel
    beams. By means of a modifying laser process, we have written channel waveguides
    inside silver-doped tellurite glassy blades. The waveguide’s optical properties and the
    writing parameters were analyzed as a function of the matrix composition and of the silver
    nanoparticles concentration. Finally, we have built annular waveguides, capable for
    guiding light beams carrying orbital angular momentum, inside boroaluminosilicate
    glassy blades. In addition, we have proposed a coupling method that permits tuning the
    guided modes for the same waveguide and no need to modify the input beam. Our findings
    expand the available degrees of freedom for optical beams in photonic circuits, simplify
    the design of integrated optical chips and broaden the spectrum of possible applications
    for these systems.

     
     
3
  • LEONARDO SOBREIRA RODRIGUES
  • Poly(ε-caprolactone) fiber containing wax and red propolis extract from Alagoas for applications in the health area

  • Advisor : LIGIA MARIA MANZINE COSTA
  • COMMITTEE MEMBERS :
  • RAFAEL SALOMÂO
  • MÁRCIA REGINA DE MOURA AOUADA
  • ADRIANA CARLA DE OLIVEIRA LOPES
  • ADRIANA SANTOS RIBEIRO
  • CAMILA BRAGA DORNELAS
  • JOHNNATAN DUARTE DE FREITAS
  • LIGIA MARIA MANZINE COSTA
  • Data: Mar 7, 2023


  • Show Abstract
  • Since ancient times, the use of biomaterials has evolved along with civilization through various technological improvements over the years. In recent times, there has been a growing interest in combining two or more substances to form a new material, due to their synergistic properties resulting in improved properties. The red propolis extract is a promising additive that can increase bioactivity when incorporated into a material. Red propolis wax, on the other hand, is discarded as waste and has no commercial value. Therefore, this study aims to produce mats from polycaprolactone (PCL) incorporated with red propolis wax or hydroalcoholic extract from Alagoas red propolis, using the electrospinning technique to ensure the formation of fibrous structures. The concentrations of wax and red propolis extract ranged from 1% to 15%. The mats were evaluated for their physical, chemical, structural, vibrational, thermal, mechanical, and biological properties. High-performance liquid chromatography was employed to determine the flavonoid content of the red propolis extract, which was found to be higher than that of the wax. The morphology of the mats was analyzed by scanning electron microscopy, revealing an average diameter below 1.2 μm and an average porosity of approximately 52%. The vibrational spectrum was used to investigate the nature of the interactions, which were found to be strictly physical without the formation of new chemical bonds. X-ray diffraction was employed to investigate the crystallinity of the mats, and a decrease in crystallinity was observed as the wax/red propolis extract was added to the polymeric matrix. The wetting behavior of the mats was analyzed using the contact angle method, and it was found that samples with propolis extract presented greater swelling, with a contact angle of less than 90º, being wettable when the concentration is equal to or greater than 5%. Mechanical testing showed that the mat with 10% propolis exhibited the best values for maximum stress, elongation at break, and elastic modulus. Furthermore, these mats did not exhibit any toxic effects on cells. These results suggest that it was possible to form a fibrous biomaterial with potential for use in tissue engineering, such as bioactive dressings.

4
  • WILLIAMS RAPHAEL DE SOUZA MORAIS
  • DEVELOPMENT OF GREEN CORROSION INHIBITORS DERIVED FROM PLANT EXTRACTS

  • Advisor : JOSEALDO TONHOLO
  • COMMITTEE MEMBERS :
  • LIU YAO CHO
  • EDUARDO JORGE DA SILVA FONSECA
  • JOSEALDO TONHOLO
  • MARCOS VINICIUS DIAS VERMELHO
  • NATHALIA MARCELINO PEREIRA QUEIROZ
  • Data: Jun 30, 2023


  • Show Abstract
  • Metallic materials and metallic alloys, are widely used as materials in the most diverse areas, due to their advantages. Carbon steel, for example, is the most widely used metal alloy and one of the most widely produced materials in the world.  On the other hand, most metals and their alloys in their pure form are highly reactive and suffer corrosion, a thermodynamically spontaneous process, resulting in their deterioration. One of the most practical methods of protecting materials is the use of corrosion inhibitors. Some inhibitors, however, are potentially polluting and harmful to human health, this motivates the search for new formulations. The literature reports the use of natural products, called "green inhibitors", the plant extracts stand out within this class of inhibitors. In this perspective, in the present work it was accomplished a prospection about the applicability of vegetal extracts as green inhibitors of corrosion and the development of these inhibitors from 3 vegetal extracts of different sources: leaves of Eucalyptus globulus Labill, Sargassum vulgare seaweed and grains of Paullinia cupana (guaraná), in the protection of the 1020 carbon steel. In the prospection bases of scientific articles and patents were consulted and the documents found were analysed. The extracts were characterized by spectroscopic and chromatographic techniques, and their inhibition activities were evaluated by gravimetric and electrochemical techniques. A total of 335 articles and 42 patents related to the theme were retrieved, being most of the extracts prepared from leaves for the protection of carbon steel in acid medium. In the characterization of the extracts were identified types of bonds and compounds, as terpenes and phenolic acids, that demonstrate the possibility of application of these extracts as corrosion inhibitors. The used techniques showed that in all studied concentrations the extracts increased the charge transfer resistance, provoked potential displacement and decreased the parameters related to corrosion, reaching 89.97 % of maximum anticorrosive efficiency. Moreover, the adsorption of molecules, in the presence of the extracts, on active sites of the carbon steel surface was physisorption and obeyed the Frumkin adsorption isotherm. The proposed inhibitors are presented as non-toxic, cheap, abundantly available in nature and of easy extraction, characterizing them as green corrosion inhibitors.

5
  • JOSÉ ANTONIO FRANÇA DE ARAÚJO
  • STUDY ON MEAN FIELD MICROMECHANICAL MODELS FOR HOMOGENIZATION OF ELASTOPLASTIC COMPOSITES AND POROUS MATERIALS

  • Advisor : SEVERINO PEREIRA CAVALCANTI MARQUES
  • COMMITTEE MEMBERS :
  • SAMIR MAGHOUS
  • ADEILDO SOARES RAMOS JUNIOR
  • EDUARDO NOBRE LAGES
  • JOSE JULIO DE CERQUEIRA PITUBA
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • SEVERINO PEREIRA CAVALCANTI MARQUES
  • Data: Aug 29, 2023
    Ata de defesa assinada:


  • Show Abstract
  • In this work, the effective elastic properties and elastoplastic behavior of biphasic materials were investigated through the micromechanics of mean fields. The materials have solid inclusions perfectly adhered to the matrix or randomly distributed pores in space, which can be aligned or misaligned. The elastoplastic behavior of the effective material is evaluated in the form of stress (or strain) rate using the incremental and homogenized method according to the Mori-Tanaka scheme. The flow of the biphasic material matrix is governed by the von Mises criterion, in which isotropic conditions and infinitesimal deformations are considered. After the flow, the isotropic constitutive tensor of the matrix takes the form of an anisotropic tangent constitutive tensor, in which, by mathematical approximation methods, the isotropic part can be used to determine the effective tangent constitutive tensor. During the elastoplastic behavior, it is assumed that the matrix has nonlinear isotropic hardening or linear kinematic hardening. To achieve the objectives of this work, algorithms were developed that enable the investigation of the limitations of using the tangent constitutive operator of the matrix, whether anisotropic or obtained by isotropic approximation, as well as the application of the tangent Eshelby tensor or Eshelby tensor for the Elastoplastic medium (EPM). The results obtained indicate that the accuracy of the elastoplastic behavior of a heterogeneous material can be affected by the choice of the method and the isotropic approximation procedure of the elastoplastic matrix constitutive operator. It was also observed that in composites that have rigid inclusions with ellipsoidal geometry, the Eshelby tensor for the EPM had limitations, providing satisfactory results only for rigid inclusions with spherical geometry. On the other hand, no limitations were observed regarding the pore geometry, showing satisfactory results for any aspect ratio. Finally, using the Eshelby tensor for the EPM, an approach was presented that deduces the strain concentration tensor for ductile matrices that have misaligned spherical or spheroidal pores, with good agreement observed with results published in the literature. the elastoplastic medium with an emphasis on porous materials.

6
  • THEO FORTES SILVEIRA CAVALCANTI
  • DEVELOPMENT OF DENTAL MATERIALS WITH IMPROVED VALUE CONTAINING BRAZILIAN RED PROPOLIS

  • Advisor : JOSEALDO TONHOLO
  • COMMITTEE MEMBERS :
  • GUILHERME BENJAMIN BRANDAO PITTA
  • JOSE MARCOS DOS SANTOS OLIVEIRA
  • JOSEALDO TONHOLO
  • LUCAS MEILI
  • MARCOS AURELIO BOMFIM DA SILVA
  • MARCOS VINICIUS DIAS VERMELHO
  • SONIA MARIA SOARES FERREIRA
  • Data: Nov 6, 2023


  • Show Abstract
  • This thesis addresses alternative treatment for tooth caries, one of the endemic diseases that affects all humanity. It also presents the use of a natural product from regional biodiversity – Brazilian Red Propolis (PVA), an exclusive bioproduct from Alagoas, Brazil - as an additive for dental supplies that improves the quality of caries treatment, adding value and increasing treatment efficiency. The PVA obtained from a controlled source was prepared to obtain the hexane extract, which was duly qualified by liquid chromatography to determine flavonoid and phenol contents, the results of which reached between 7.35% and 117.6 mg of total phenols per gram of dry hexane extract. A DPPH scavenging study was carried out, where the IC50 of the DPPH radical scavenging capacity of the PVA hexane extract was 9.22 μg/mL while the IC50 of Trolox, used as standard, was 7.02 μg/mL. After qualifying the extract, 5 different ionomer compositions were formulated with the addition of PVA dry extract, which were subjected to antibacterial activity tests by diffusion, which confirmed the ability to release daidzein, liquiritigenin, pinobanksin, isoliquiritigenin and formononetin. Mechanical surface roughness tests were carried out, which revealed similar values between the surfaces of the glass ionomer in the control group and that of the ionomer with 0.5% hexane extract. The analysis of the microhardness of materials (Knoop hardness) proved that there was no statistically significant difference in the microhardness of the additives in relation to the commercial product of the non-additivated ionomer. The determination of the (qualitative) fluoride release profile was carried out by NMR using an unprecedented procedure, revealing the viability of fluoride release, regardless of the presence of PVA in the ionomer mixture. A fluoride release study was also carried out using fluorometry, demonstrating the quantitative release of fluoride, both in the presence and absence of PVA. The results of biological, chemical and mechanical tests, carried out in vitro and here presented, are very favorable to the indication of the use of PVA as an additive in glass ionomer, allowing us to recommend moving towards in vivo studies.

2022
Thesis
1
  • ANAMALIA FERREIRA DA SILVA
  • Study of the structural modifications in LDH-MgFe produced by different routes   to synthesis: analysis of the adsorption capacity

  • Advisor : LUCAS MEILI
  • COMMITTEE MEMBERS :
  • JOSE TEIXEIRA FREIRE
  • CAMILA BRAGA DORNELAS
  • JOSE LEANDRO DA SILVA DUARTE
  • LUCAS MEILI
  • TITO ROBERTO SANT''ANNA CADAVAL JUNIOR
  • Data: May 5, 2022


  • Show Abstract
  • Double LamellarHydroxides (LDHs) are commonlyapplied as adsorbentsto remove contaminants in aqueousmatrices. However, chemicalmethods for synthesizingLDHscanpromotevariations in theirstructure. Thisworkinvestigatedhowthe surface area, basal spacingandcrystallinity, importantparameters for theadsorption dynamics, are modifiedusingdifferentsyntheticroutestoproduce LDH-MgFe. Thus, thesynthesisbycoprecipitation at variable pH (CV) and at constant pH (CC), hydrothermalsynthesis (HC), driphydrothermal (HCG), coprecipitationfollowedbyhydrothermal (CCH), ultrasonicvibration (UHC) andmicrowaveradiation (MHC) wereanalyzedusing X-raydiffraction (XRD), scanningelectronmicroscopy (SEM), Fourier Transforminfraredspectroscopy (FTIR), N2 adsorption-desorption. The adsorptioncapacitywasquantitativelymeasuredbytheresultsofremovalofthefollowingadsorbates: Nitrate, Rifampicinand 17-α-methyltestosterone. The effectof pH, adsorbent dose, kinetics, andadsorptionequilibriumwereinvestigatedbasedonthebestresultsofcharacterizationand Life CycleAnalysis (LCA), later thethermodynamicsoftheprocesswasanalyzed. Thus, thephysicalstructureandtypical bands ofLDHswereformed in allmethods. Hydrothermaltreatmentincreasedcrystallinityand basal spacing. The surface areavariedfrom 49.5 to 84.0 m2g-1, theisothermsclassifiedthematerials in mesopores. 17-α-methyltestosteroneshowedlowselectivity, however, theaffinity for NitrateandRifampicinincreasedsignificantly in CC (69.77, 67.78%), UHC (76.63, 82.71%) and MHC (74.57, 82.50%), respectively. The simplified LCA showedthatthe use ofthe CC methodpresentedthelowestenvironmentalimpacts for acidification, climatechange, eutrophication, andhumantoxicity. The pseudo-secondorder model wastheonethatbestexplainedtheadsorptionkinetics for the CC, HC and UHC methods. The Langmuir model bestfittedtheadsorption curves for CC, HC and UHC. The thermodynamic data indicateexothermicandspontaneousprocess for CC and HC and, in UHC, as endothermicreaction. The IR spectra, beforeandafteradsorption, suggestedthatthenitratewasadsorbedbyelectrostaticinteractions in bothmethods, as well as byanionexchangeinteractionsofthehydroxylgroups in HC and UHC. Therefore, thematerialsproduceddemonstrateapplicability as adsorbents for theremovalofpollutants in anaqueousmatrix, allowingthetargetingofspecificcompoundstobecaptured, dependingonthesyntheticroutechosen. 

2
  • VALCILAINE TEIXEIRA BARBOSA
  • Bioactive primary dressings of silver nanoparticles obtained by biogenic synthesis with red propolis from Alagoas

  • Advisor : CAMILA BRAGA DORNELAS
  • COMMITTEE MEMBERS :
  • HELVÉCIO VINÍCIUS ANTUNES ROCHA
  • ADRIANA SANTOS RIBEIRO
  • CAMILA BRAGA DORNELAS
  • JOHNNATAN DUARTE DE FREITAS
  • LIGIA MARIA MANZINE COSTA
  • MARIO ROBERTO MENEGHETTI
  • Data: Jul 11, 2022


  • Show Abstract
  • Skin lesions are still considered a major challenge in the health area, considering that current dressings are, to a large extent, imported and expensive. Dressings can be primary, when used in direct contact with the injured tissue, and bioactive, with a role in the healing cascade. Thus, this work aims to develop bioactive primary dressings with polymeric matrix of polycaprolactone (PCL), containing silver nanoparticles (AgNP-P) obtained by biogenic synthesis with red propolis from Alagoas. For this, the synthesized and dried nanoparticles were incorporated in different concentrations (1, 2 and 5%) in fixed polymer concentration (9%). The dressings were prepared using casting and electrospinning techniques, resulting in films and fibers, respectively. In the case of fibers, they were optimized with the aid of scanning electron microscopy (SEM), in which average fiber diameter and porosity were seen. For the characterization of the materials were utilized techniques of X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), as well as essays of water contact angle, swelling, silver release by inductively coupled plasma optical emission spectrometry (ICP-OES), antimicrobial activity, cytotoxicity and mechanical activity. As a result, the best conditions for the fibers were a voltage of 15kV, 12 cm distance between needle-collector and needle of 1.2 mm in diameter, leading to a nanofibers porosity of approximately 85%. The crystalline planes of metallic silver visualized by XRD confirmed the presence of AgNP-P. TG curves showed a decomposition of products similar to the pure polymer, while DSC allowed observing a decrease in the melting temperature corroborated by the crystallinity of the compounds that was also reduced due to the increase in the concentration of AgNP-P. FTIR spectras revealed that AgNP-P seems to be impregnated only by physical interaction with the polymer in both production techniques. The products obtained by electrospinning showed a higher swelling and silver release capacity compared to the films. Consequently, the nanofibers with the highest concentration of silver (E-5%) showed bacterial inhibition with a release of only 0.0833 µg/mL in 24h against the evaluated bacteria, being, therefore, the product of choice for the next analyses. Finally, E-5% showed no toxicity against L929 cells, similar to fibroblasts, and exhibited properties of elasticity and resistance suitable for use as dressings. Thus, it was possible to conclude that the electrospinning processing demonstrated better results in the properties of the dressings and the use of nanoparticles biosynthesized with propolis was essential for a product with antimicrobial activity without presence of toxicity.

3
  • JULYANE DA ROCHA SANTOS SOLANO
  • SYNTHESIS OF ZEOLITE SSZ-13 WITH THE COMBINED USE OF STRUCTURE-DIRECTING AGENTS AND SEED CRYSTALS

  • Advisor : ANTONIO OSIMAR SOUSA DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO OSIMAR SOUSA DA SILVA
  • ANTONIO SOUZA ARAÚJO
  • BRUNO JOSÉ BARROS DA SILVA
  • FABIANE CAXICO DE ABREU GALDINO
  • LUCAS MEILI
  • Data: Jul 22, 2022


  • Show Abstract
  • Zeolites with inorganic crystalline structures have been widely used in industry because of their excellent properties. The development of zeolite synthesis strategies facilitates the creation of new zeolite materials, the improvement of synthetic efficiency and the adjustment of the physicochemical properties of the material. Recent efforts have focused on improving the SSZ-13 synthesis routes with minimal maintenance cost while maintaining, or even increasing, its performance. The present research addressed the optimization of the synthesis of SSZ-13 zeolite. For this, the synthesis was carried out using choline chloride, hexamethylenetetramine, betaine, 1-(cis-3- chloroallyl)-3,5,7-triazo-1-azoniaadamantane chloride and 5-ethyl-1-azo- 3,7- dioxabicyclo[3.3.0]octane as structure-directing agents combined with seed crystals. The seed crystals, with CHA structure, were synthesized from an inorganic gel obtained by the interzeolitic transformation of faujasite zeolite. Some important synthesis parameters for obtaining SSZ-13 zeolite were evaluated, such as: directing/SiO2 molar ratio = 0.10, 0.40 or 0.8, OH/SiO2 molar ratio = 0.4 or 0.8, percentage of seed crystals 2.5% or 10% and crystallization times between 24 to 72 hours. The samples were characterized by X-ray diffractometry, energy dispersive Xray spectroscopy, thermal analysis, scanning electron microscopy, nitrogen adsorption-desorption and ammonia desorption at programmed temperature. The catalysts that presented better textural properties were submitted to the catalytic test with n-hexane cracking model reaction. The XRD results revealed that among the structure- directing agents used, only choline chloride and hexamethylenetetramine were effective for the formation of pure SSZ-13 with 24 hours and 48 hours of crystallization, respectively. It was found, in all cases, in the region of lower alkalinity (OH/SiO2 = 0.4), the presence of amorphous materials even with a crystallization time of 72 hours. For choline chloride syntheses, the increase in alkalinity (OH/SiO2 = 0.8) promoted nucleation and crystal growth leading to the formation of SSZ-13 with high purity and crystallinity, regardless of the percentage of seed crystals. However, the syntheses with hexamethylenetetramine were only efficient with the percentage of seed crystals of 10%. The EDX results showed that the samples containing the SSZ13 phase presented very close values of SiO2/Al2O3 ratio, between 9 and 11, indicating a restricted range of SSZ-13 zeolite formation. The samples showed morphology of agglomerates of cubic intergrown crystals and textural and acidic properties characteristic of the CHA structure. The catalytic activity results showed that the sample synthesized with choline chloride suffered a greater deactivation of parts of its acid sites by the deposition of coke, resulting in a lower conversion (about 21%) when compared to the sample synthesized with hexamethylenetetramine, which presents a total acidity lower, but achieved a conversion of approximately 25% and a coke content of only 8.3%.
4
  • DIOGO CARLOS HENRIQUE
  • PRODUCTION OF CaAl/HDL FROM CALCINATED WASTE OF THE SHELL OF Mytella falcata

  • Advisor : LUCAS MEILI
  • COMMITTEE MEMBERS :
  • CAMILA BRAGA DORNELAS
  • DANIEL PINTO FERNANDES
  • DISON STRACKE PFINGSTEN FRANCO
  • JOSE LEANDRO DA SILVA DUARTE
  • LUCAS MEILI
  • ROBSON COSTA DE SOUSA
  • Data: Sep 12, 2022


  • Show Abstract
  • The volume of waste produced by malacoculture activities generates great impact and high costs for proper treatment and disposal, constituting one of the greatest environmental problems in the world. Faced with this problem, for the first time, the feasibility of introducing malacoculture residue for the production of lamellar double hydroxides (HDLs) was studied. Shells of Mytella falcata were used to produce calcium oxide, which was later used as a reagent for the synthesis of HDL by the coprecipitation method. The thermal behavior of the materials was mapped up to 900 °C by determining the TG/DTG curves, while the textural and surface characteristics were studied by zero charge pH (pHPCZ), Scanning Electron Microscopy (SEM) and by adsorption/ N2 desorption (BET, BJH), composition was determined by Energy Dispersive X-ray Spectroscopy (EDS), chemical groups by Fourier Transform Infrared (FTIR) and crystallinity along with other structural properties were determined by X-Ray Diffraction (DRX). The characterizations allowed to identify the composition of Mytella falcata residue, consisting mainly of calcium carbonate with aragonite and calcite polymorphs, low surface area, irregular and rough morphology composed of a conglomerate of overlapping plates. Calcium oxide was obtained from shells with temperatures above 800°C, showed morphology, particle size distribution, decomposition intervals, crystallinity and other characteristics similar to the commercial material, indicating that it is a possible substitute for HDL synthesis. The material CaAl/HDL – RE was produced with calcium oxide from the residue of Mytella falcata with high crystallinity, surface area 65.62% greater than the material (CaAl/HDL – PA), produced with commercial reagent, classified as mesoporous, formed by plates in the form of hexagonal sheets arranged in an overlapping fashion, with a zero charge potential equal to 12.25. With removal efficiency of 98.51% of malachite green dye and 23.30% greater capacity than CaAl/HDL – PA for the removal of the antibiotic Sulfanilamide. Thus, these results corroborate the thesis that it is possible to use Mytella Falcata Residue (RMF) for the production of CaO – RE and synthesis of CaAl/HDL – RE

SIGAA | NTI - Núcleo de Tecnologia da Informação - (82) 3214-1015 | Copyright © 2006-2024 - UFAL - sig-app-2.srv2inst1 29/03/2024 04:42