[pt] Os elementos terras raras (ETRs) têm sido cada vez mais utilizados na indústria moderna como os componentes essenciais de catalisadores, ímãs de alto desempenho, supercondutores, sistemas de telecomunicações. O desenvolvimento da energia limpa aumentará ainda mais a demanda, pois ETRs são usados na produção de baterias e painéis solares. O processo de produção ambientalmente sustentável substituirá ou complementará as fontes atuais. Assim, a separação e a reciclagem de ETRs são de grande importância para diversificar as fontes dos ETRs. A maioria das tecnologias atuais para o enriquecimento de ETRs é baseada na extração de solventes e troca iônica. Elas não são sustentáveis e não são aplicáveis ao tratamento de lixo eletrônico. Um dos primeiros adsorventes seletivos para extração em fase sólida dos ETRs foi proposto recentemente (Callura et al., 2018). A presente pesquisa estudou 3 adsorventes organo-sílicas (OSAd) com fragmentos imobilizados covalentemente de N-Benzoil-N-fenil-hidroxilamina (BPHA), ácido 2,6-piridinodicarboxílico (PdCA) e ácido amino di(metilenofosfônico) (AdMPA). Foi mostrado que os adsorventes podem ser utilizados com sucesso para separação e preconcentração dos elementos terras raras das soluções aquosas. A pesquisa demonstrou a alta afinidade dos adsorventes aos ETRs (La3+ - Lu3+), Sc3+ e Y3+. A adsorção competitiva dos ETRs da solução multielementar, sua dependência de pH, isotermas e estudos de cinética, recuperação e dessorção de íons metálicos, bem como a reutilização de adsorventes foram investigados. A caracterização qualitativa e quantitativa dos adsorventes foi estudada por espectroscopia no infravermelho por transformada de Fourier, espectroscopia de fotoelétrons de raios-X de alta resolução, análise RMN no estado solido, medições BET, análise elementar e termogravimétrica. Foi demonstrado que os OSAd propostos podem ser utilizados com sucesso para remover íons ETR da solução aquosa em 10 minutos. Os adsorventes demonstram diferenças essenciais na afinidade para ETRs que permitem a utilização dos OSAd para vários fins, incluindo pré-concentração para determinação de traços de ETRs em água natural, separação de ETRs dos outros metais em lixo eletrônico, e a separação individual dos ETRs. A pesquisa demonstra que o SiO2-BPHA pode recuperar todos os ETRs de solução com pH maior ou igual a 5.0 e liberá-los após eluição de 0.1 mol L-1 HNO3 com eficiência superior a 95 por cento. Outros OSAd - SiO2-PdCA e SiO2-AdMPA são os únicos adsorventes que podem remover os íons ETRs da solução aquosa em pH maior ou igual a 2. Devido a isso, SiO2-PdCA e SiO2-AdMPA podem ser usados para a reciclagem dos ETRs do lixo eletrônico. Foi demonstrado que o SiO2 PdCA pode ser utilizado para a recuperação seletiva de elementos de terras raras (Y, Eu, Tb) dos resíduos de lâmpadas fluorescentes. SiO2-PdCA demonstra alta seletividade que permite recuperação completa (maior que 95 por cento) de todos os ETRs na presença de excesso (50 vezes) de íons Ba2+ que é útil para determinação analítica de traços dos ETRs por ICP-MS. Além disso, SiO2-PdCA é útil para a adsorção seletiva dos ETRs de amostras ambientais, pois o excesso de 200 vezes de íons Fe3+, Cu2+, Ca2+, Mg2+, Na+, K+ e Al3+ predominantes em amostras ambientais, causa pouca interferência na eficiência do adsorvente. SiO2-BPHA demonstra maior seletividade para ETRs pesados. Em condições ótimas, o fator de seletividade é cerca de 80 (para pares Lu/La e Yb/La) e cerca de 60 (para o par Tm/La), que demonstra alto potencial do SiO2-BPHA na separação individual dos ETRs. Estudos de reusabilidade demonstram que SiO2-BPHA pode ser usado para adsorção quantitativa de quase todos os ETRs (adsorção média de Ce e Pr é cerca de 90 por cento) de uma solução multielementar com pH igual a 5.0 sem perda na capacidade de adsorção e seletividade por pelo menos cinco ciclos. Foi demonstrado que a adsorção de metais por OSAd ocorre devido à formação de complexos entre o ligante imobilizado e os íons metálicos. Por exemplo, a adsorção de íons Eu3+ e Tb3+ por SiO2-PdCA e SiO2-AdMPA gera luminescência forte de cor vermelha e verde, respectivamente. A adsorção de Fe3+ em SiO2-BPHA leva ao desenvolvimento da cor vermelha do adsorvente cuja intensidade é proporcional à concentração de metal adsorvido. Os complexos metálicos imobilizados são muito estáveis em água e meios orgânicos e podem ser usados para o desenvolvimento de sensores ópticos dos ETRs e fases cromatográficas de troca de ligante. / [en] Rare earth elements (REEs) have been increasingly used in modern industry as essential components of many catalysts, high-performance magnets, superconductors, telecommunication systems. Clean energy development will further boost the demand for REEs since they are used in the production of batteries and solar panels. Environmentally sustainable production process shall substitute or supplement current ore sources. Thus, separation and recycling of REEs are of great importance to diversify the sources of REEs. Most existing technologies for enrichment of REEs are based on solvent extraction and ion exchange. They are not sustainable and are not applicable to electronic waste (e-waste) treatment. One of the first selective adsorbent for REEs SPE extraction was proposed recently (Callura et al., 2018). The research proposed demonstrates other organo-silica adsorbents (OSAd) with covalently immobilized fragments of N-Benzoyl-Nphenylhydroxylamine (BPHA), 2,6-pyridinedicarboxylic acid (PdCA) and aminodi(methylene-phosphonic) acid (AdMPA) can be successfully used both for preconcentration and separation of REEs. This research demonstrates high affinity of the adsorbents to REE (La3+ - Lu3+), Sc3+ and Y3+. Competitive adsorption of REEs from multielement solution and pH dependence, isotherm and kinetics studies, metal ion recovery and desorption, as well as the adsorbent reusability have been investigated. The research is accomplished with qualitative and quantitative characterization of the adsorbent, physical and chemical properties using Fourier transform infrared spectroscopy, high-resolution X-ray photoelectron spectroscopy, solid-state NMR, BET measurements, elemental and thermogravimetric analysis. It has been demonstrated that the proposed OSAd can be successfully used to remove REE ions from aqueous solution within 10 min. Sharp changes of REEs recovery has been observed in a narrow range of the pH that allows developing a methodology for removal of REEs from solution. The adsorbents demonstrate an essential difference in REE affinity that allows utilization of the OSAd for various purposes, including pre-concentration for determination of REE traces in natural waters, separation of REE from color and other metals in e-waste, separation of individual REE. It is demonstrated that SiO2-BPHA can recover all REE from solution with pH bigger or equal 5.0 and release them to solution under treatment with 0.1 M HNO3 with efficiency more than 95 percent. Additionally, OSAd - SiO2-PdCA and SiO2- AdMPA are the only adsorbents that can remove REE ions from aqueous solution with pH bigger or equal 2. Because of this SiO2-PdCA and SiO2-AdMPA can be used for the recycling of rare earth elements from electronic waste. It was demonstrated that SiO2-PdCA can be used for selective recovery of rare earth elements (Y, Eu, Tb) from waste fluorescent lamps. SiO2-PdCA demonstrates high selectivity that allows complete (bigger 95 percent) recovery of all REE in the presence of 50-fold excess of Ba2+ ions that is used for analytical determination of REE traces by ICP-MS. Also, SiO2- PdCA is useful for selective adsorption of REE from environmental objects since 200-fold excess of such ions as Fe3+, Cu2+, Ca2+, Mg2+, Na+ , K+ and Al3+ which are predominate in environmental objects cause little interference on the adsorbent removal efficiency. SiO2-BPHA demonstrates higher selectivity towards heavy REEs. In optimal conditions selectivity factor is about 80 (for Lu/La and Yb/La pairs) and about 60 (for Tm/La pair), which demonstrates the high potential of SiO2- BPHA in separation of individual REEs. Reusability test demonstrates that SiO2- BPHA can be used for quantitative adsorption of almost all REEs (average adsorption of Ce and Pr ions is about 90 percent) from multielement solution with pH equal 5.0 without lost in adsorption capacity and selectivity for at least five consecutive cycles. It is demonstrated that adsorption of metals on the OSAd takes place due to complex formation between immobilized ligand and metal ions. For example, adsorption of Eu3+ and Tb3+ ions on SiO2-PdCA and SiO2-AdMPA generates strong red and green luminescence, respectively. Adsorption of Fe3+ on SiO2-BPHA leads to development of red color of the adsorbent which intensity is proportional to metal loading. Immobilized metal complexes are very stable in water and organic media that can be used for further development of optical sensors for REE and stationary phases for ligand-exchange chromatography.

A bench-scale tubular reactor with recirculation was built in order to study the efficiency of the photocatalytic oxidation of phenol on fluidized titanium oxide-coated silica gel beads. A UV-C lamp placed along the central vertical axes of the reactor was used as source of photons. A bed of silica gel beads was fluidized by means of fluid recirculation and forced to follow upward helical flow around the lamp. Anatase was successfully synthetized on silica gel particles of average diameters 224, 357 and 461 µm, as confirmed by scanning electron micrographs, through a sol-gel technique using a titanium (iv)isopropoxide / hydrochloric acid / ethanol precursor. Data was obtained from multiple 8-hours photocatalytic experiments using a determined mass of beads fluidized in an aqueous solution of known initial phenol concentration. Contaminant degradation with irradiation time was measured as COD. Beads that had been subjected to three consecutive coating procedures produced an 8-h removal efficiency 10% higher than beads with a single coat. 20 g L-1 of silica beads was found to be the optimum load for the experimental reactor configuration regardless of beads size, although efficiency increased with decreasing size of the latter. Experimental results confirmed that the efficiency of phenol photocatalytic degradation decreases with increasing pollutant concentration. Also, the highest removal was achieved with initial pH 3, and it decreased with increasing pH. When NaCl was added to the solution, COD removal increased with increasing salinity. Additionally, it was found that dissolved oxygen is indispensable for photocatalysis to proceed, and that saturation of the treated mixture with oxygen was effectively achieved by keeping the liquid surface in contact with pure oxygen at 1 atm. Finally, statistical analysis of the data showed that photocatalytic mineralization of phenol-derived COD under the experimental conditions follows exponential decay. Based on this finding, a correlation model was proposed for the accurate prediction (minimum R2 = 0.9840) of the COD removal efficiency of the reactor for any given initial COD.

Heat actuated adsorption heat pumps offer the opportunity to improve overall energy efficiency in waste heat applications by eliminating shaft work requirements accompanying vapor compression cycles. The coefficient of performance (COP) in adsorption heat pumps is generally low. The objective of this thesis is to model the adsorption system to gain critical insight into how its performance can be improved. Because adsorption heat pumps are intermittent devices, which induce cooling by adsorbing refrigerant in a sorption bed heat/mass exchanger, transient models must be used to predict performance. In this thesis, such models are developed at the adsorbent particle level, heat/mass exchanger component level and system level. Adsorption heat pump modeling is a coupled heat and mass transfer problem. Intra-particle mass transfer resistance and sorption bed heat transfer resistance are shown to be significant, but for very fine particle sizes, inter-particle resistance may also be important. The diameter of the adsorbent particle in a packed bed is optimized to balance inter- and intra-particle resistances and improve sorption rate. In the literature, the linear driving force (LDF) approximation for intra-particle mass transfer is commonly used in place of the Fickian diffusion equation to reduce computation time; however, it is shown that the error in uptake prediction associated with the LDF depends on the working pair, half-cycle time, adsorbent particle radius, and operating temperatures at hand. Different methods for enhancing sorption bed heat/mass transfer have been proposed in the literature including the use of binders, adsorbent compacting, and complex extended surface geometries. To maintain high reliability, the simple, robust annular-finned-tube geometry with packed adsorbent is specified in this work. The effects of tube diameter, fin pitch and fin height on thermal conductance, metal/adsorbent mass ratio and COP are studied. As one might expect, many closely spaced fins, or high fin density, yields high thermal conductance; however, it is found that the increased inert metal mass associated with the high fin density diminishes COP. It is also found that thin adsorbent layers with low effective conduction resistance lead to high thermal conductance. As adsorbent layer thickness decreases, the relative importance of tube-side convective resistance rises, so mini-channel sized tubes are used. After selecting the proper tube geometry, an overall thermal conductance is calculated for use in a lumped-parameter sorption bed simulation. To evaluate the accuracy of the lumped-parameter approach, a distributed parameter sorption bed simulation is developed for comparison. Using the finite difference method, the distributed parameter model is used to track temperature and refrigerant distributions in the finned tube and adsorbent layer. The distributed-parameter tube model is shown to be in agreement with the lumped-parameter model, thus independently verifying the overall UA calculation and the lumped-parameter sorption bed model. After evaluating the accuracy of the lumped-parameter model, it is used to develop a system-level heat pump simulation. This simulation is used to investigate a non-recuperative two-bed heat pump containing activated carbon fiber-ethanol and silica gel-water working pairs. The two-bed configuration is investigated because it yields a desirable compromise between the number of components (heat exchangers, pumps, valves, etc.) and steady cooling rate. For non-recuperative two-bed adsorption heat pumps, the average COP prediction in the literature is 0.39 for experiments and 0.44 for models. It is important to improve the COP in mobile waste heat applications because without high COP, the available waste heat during startup or idle may be insufficient to deliver the desired cooling duty. In this thesis, a COP of 0.53 is predicted for the non-recuperative, silica gel-water chiller. If thermal energy recovery is incorporated into the cycle, a COP as high as 0.64 is predicted for a 90, 35 and 7.0°C source, ambient and average evaporator temperature, respectively. The improvement in COP over heat pumps appearing in the literature is attributed to the adsorbent particle size optimization and careful selection of sorption bed heat exchanger geometry.

Data de aprova??o retirada da vers?o impressa do trabalho. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-08-30T18:13:36Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-08-30T18:51:12Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) / Made available in DSpace on 2017-08-30T18:51:12Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gelson_cerqueira_oliveira_junior.pdf: 2578577 bytes, checksum: 83cb8ab9378ea856fed151a0f1c1992d (MD5) Previous issue date: 2015 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho s?lica gel foi preparada a partir de areia de constru??o e carbonato de s?dio, apresentando uma ?rea de superf?cie de 378,68 m2/g, e volume de poro de 1,59x10-2 cm3/g. A fim de preparar diferentes catalisadores a base do mesmo material uma al?quota foi previamente aquecida a 400? C e outra a 700? C, as quais foram denominadas S400 e S700 que ap?s tratamento com H2SO4, deram origem a dois diferentes catalisadores, chamados de C400 e C700. Os catalisadores apresentaram volume total dos mesoporos de 0,23 cm3/g (C400) e 0,20 cm3/g (C700) e ?rea superficial de 31,06 m2/g (C400) e 23,10 m2/g (C700). Pela primeira vez foi utilizado ?cido de Bronsted imobilizado em s?lica para a convers?o de OGR em biodiesel. Ambos C400 e C700 apresentaram alta atividade na convers?o do ?leo e gordura residuais altamente ?cidos (13,7 mg de KOH) e com teor de ?gua de 0,58%, a biodiesel (?steres met?licos de ?cido graxo) em aproximadamente 99,4 %. As rea??es foram repetidas 4 vezes antes do catalisador perder sua atividade catal?tica. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015. / In this work, silica gel was prepared from building sand and sodium carbonate, having a surface area of 378.68 m2/g and pore volume of 1,59x10-2 cm3/g. In order to prepare different catalysts the basis of the same material aliquot was preheated to 400? C and another at 700? C, which were referred to as S400 and S700 which upon treatment with H2SO4, gave rise to two different catalysts, called C400 and C700. The catalysts showed total volume of mesopores of 0.23 cm3/g (C400) and 0.20 cm3/g (C700) and surface area of 31.06 m2/g (C400) and 23.10 m2/g (C700). For the first time was used Bronsted acid immobilized on silica OGR for conversion into biodiesel. Both C400 and C700 showed high activity in the oil conversion and highly acidic waste fat (13.7 mg of KOH) and 0.58% water content, biodiesel (fatty acid methyl esters) by approximately 99.4% . Reactions were repeated four times before the catalyst to lose its catalytic activity.

Submitted by ANA FLÁVIA NUNES E REIS null (dra-anaflavia@uol.com.br) on 2016-01-26T19:16:31Z No. of bitstreams: 1 merged (4).pdf: 4937949 bytes, checksum: c052666784bd930ac4748e41040c73bd (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-01-28T13:31:20Z (GMT) No. of bitstreams: 1 reis_afn_me_sjc.pdf: 4937949 bytes, checksum: c052666784bd930ac4748e41040c73bd (MD5) / Made available in DSpace on 2016-01-28T13:31:20Z (GMT). No. of bitstreams: 1 reis_afn_me_sjc.pdf: 4937949 bytes, checksum: c052666784bd930ac4748e41040c73bd (MD5) Previous issue date: 2015-12-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi infiltrar sílica em uma cerâmica Y-TZP, avaliar seu efeito na resistência à flexão Biaxial, e na união com a porcelana feldspática. Para a análise da resistência à flexão foram confeccionados 180 discos de zircônia, 120 de 0,5mm e 60 com 1,2mm discos (14 mm de diâmetro). 90 discos foram infiltrados com sílica pelo método sol-gel em temperatura ambiente (n = 30). A espessura do disco foi de 1,2 mm para os espécimes controle (espécime sem porcelana, n = 30). O recobrimento por porcelana feldspática foi de duas espessuras (0,5mm e 1 mm) sobre a zircônia que tinha 0,5 mm. Os espécimes com porcelana foram polidos com lixas de carbeto de silício (SiC) de granulação # 400, 600, 800 e 1200. Obtivemos 6 grupos: dois monolíticos (ZR- Zircônia Monolítica sem infiltração e ZRI- Zircônia Monolítica Infiltrada) (controle) e quatro estratificados: ZRF 1,0 (0,5mm Zircônia coberta com 0,5 mm porcelana), ZRIF 1,0 (0,5 mm Zircônia infiltrada coberta com 0,5 mm de porcelana), ZRF 1,5 (0,5 mm Zircônia infiltrada coberta com 1,0 mm de porcelana) ZRIF 1,5- Zircônia infiltrada (0,5 mm Zircônia infiltrada coberta com 1,0 mm de porcelana). Após o ensaio de flexão biaxial em meio aquoso, foram determinados o módulo de Weibull (m) e resistência característica (σθ). Os fragmentos foram analisados em EDS, MEV, DRX e FTIR. A Dureza (H) e tenacidade a fratura foram analisadas pela nanoindentação, já o módulo elástico (E) por duas técnicas, nanoindentação e por impulso, e para avaliar a adesão entre a zircônia e a porcelana foi aplicado o Teste de Scratch. Foram modeladas 7 condições experimentais e analisados pelo método por elementos finitos. A zircônia monolítica infiltrada mostrou uma estrutura com grãos arredondados envoltos em uma matriz de sílica, e a presença de zircônia cúbica e tetragonal. O DRX revelou a formação de ZrSiO4 nos grupos infiltrados. Os grupos monolíticos apresentaram módulos de Weibull superiores aos dos grupos com porcelana. Com a análise (AEF) não houve diferença entre os grupos com a mesma espessura, já para o grupo recoberto com 0,5 mm de porcelana, os valores de tração e compressão foram maiores. A cerâmica infiltrada apresentou microestrutura diferente, e a adesão da porcelana à zircônia não-infiltrada foi superior à da zircônia infiltrada. / The objective was to infiltrate silica in a Y- TZP ceramics, evaluate its effect on resistance biaxial strenght, and the union with feldspathic porcelain. For the analysis of flexural strength were prepared zirconia discs 180, 120 and 60 of 0.5 mm to 1.2 mm disks (14 mm diameter). 90 discs were infiltrated with silica by the sol-gel method at room temperature (n = 30). The thickness of the disk was 1.2 mm for the samples control (no porcelain specimen, n = 30). The coating was feldspathic porcelain by two thicknesses (0.5 mm and 1 mm) of zirconia, which had 0.5 mm. Specimens with porcelain were polished with sandpaper silicon carbide (SiC) granulation # 400, 600, 800 and 1200. We obtained six groups: two monolithic (Zr-Zirconia Monolithic without infiltration and ZRI- Zirconia monolithic Infiltrated) (control) and four laminated ZRF 1.0 (0.5 mm zirconia covered with 0.5 mm porcelain), ZRIF 1.0 (0.5 mm infiltrated zirconia covered with 0.5 mm of porcelain), ZRF 1.5 (0.5 mm infiltrated zirconia covered with 1.0 mm of porcelain) ZRIF 1,5-infiltrated Zirconia (0.5 mm infiltrated zirconia covered with 1.0 mm of porcelain). After the biaxial bending test in an aqueous medium were determined Weibull modulus (m) and the characteristic strength (σθ). The fragments were analyzed by EDS, SEM, XRD and FTIR. The hardness (H) and fracture toughness were analyzed by nanoindentation, since the elastic modulus (E) by two techniques, nanoindentation and on impulse, and to evaluate the adhesion between the zirconia and porcelain was applied Scratch Test. 7 experimental conditions were modeled and analyzed by the finite element method. The infiltrated zirconia showed a monolithic structure with rounded grain wrapped in a silica matrix, and the presence of cubic and tetragonal zirconia. The XRD showed the formation of ZrSiO4 infiltrates in groups. The monolithic modules Weibull groups showed superior to porcelain groups. With the analysis (FEA) there was no difference between the groups with the same thickness, for now the group covered with 0.5 mm of porcelain, the tensile and compressive values were higher. The infiltrated ceramic showed different microstructure, and the accession of porcelain to non- infiltrated zirconia was higher than the infiltrated zirconia.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Organic and inorganic materials have been used as adsorbent materials of aquatic pollutants due to their both good adsorption capacities and physical and chemical stabilities. In this work, the ligand 3-aminopropytrimethoxysilane was immobilized on silica gel surface, with consecutive reactions with glutaraldehyde and chitosan. All materials were characterized by TG/DTG, DSC, FTIR, DRX and MEV, where the presence of the silica-immobilized chitosan was evidenced. The adsorption kinetics of the anionic dye remazol blue (AR) on the cross linked silica/chitosan (Sil-Quit-R) was studied in the temperature range of 25 - 55 ºC and initial dye concentration of 23 - 800 mg L-1. The results were best fitted to both the pseudo second-order Ho and McKay and the Avrami models. The AR dye adsorption at chemical equilibrium were best described using the three-parameter Redlich-Peterson I, Sips, Tóth, Baudu I and five-parameter Fritz-Schlunder IV models. From these results, the heterogeneity of the Sil-Quit-R adsorption sites was evidenced. The adsorption enthalpies (ΔadsH) were all endothermic and increased with the increasing of adsorption temperature. The negative values for ΔadsG have indicated that the adsorption processes are spontaneous. The adsorption entropies (ΔadsS) were all positive and increased with the increasing of adsorption temperature. From the thermodynamic viewpoint, the positive ΔadsS values were the adsorption driving force. The adsorption capacity of Sil-Quit-R was good, mainly related to the adsorption results at low dye concentrations in solution. / Matrizes orgânicas e inorgânicas têm sido utilizadas como materiais para remoção de poluentes aquáticos, dada às suas boas capacidades de adsorção e estabilidades físicas e químicas. Neste trabalho, foi sintetizado e caracterizado o material híbrido orgânico/inorgânico Sílica/Quitosana Reticulado (Sil-Quit-R) através da formação de ligações cruzadas, sendo caracterizados por TG/DTG, DSC, FTIR, DRX e MEV e avaliada as suas interações com o corante Azul de Remazol (AR). Na avaliação da cinética de interação do corante (AR) na (Sil-Quit-R), foi feita entre 25 e 55ºC, nas concentrações do corante entre 23 a 800 mg.L-1. Os modelos de Difusão Intrapartícula e de Avrami mostraram os melhores ajustes. Evidenciaram-se também várias etapas cinéticas de difusão em relação ao tempo de contato. As adsorções nos equilíbrios químicos foram mais bem descritas pelos modelos de três parâmetros ajustáveis de Redlich-Peterson I, Sips, Tóth, Baudu I e para o modelo de cinco parâmetros ajustáveis de Fritz-Schlunder IV. Esses resultados evidenciaram a heterogeneidade dos sítios de adsorção da Sil-Quit-R. Os valores das entalpias de adsorção (ΔadsH) foram maiores que zero indicando processos endotérmicos e aumentaram com o aumento da temperatura de adsorção. Os valores negativos de ΔadsG indicaram a espontaneidade dos processos de adsorção. As entropias das adsorções (ΔadsS) foram positivas e aumentaram com o aumento da temperatura de adsorção, sendo, termodinamicamente, a força motriz dos processos de adsorção. As capacidades de adsorção máximas do material podem ser consideradas bem evidenciadas com um qemax em todas as concentrações e temperaturas, principalmente quando o corante Azul de Remazol estava presente em baixas concentrações em solução.

Die Durchströmungswäsche von Filterkuchen aus innenporösen Partikeln wird anhand von makro- und mesoporösen Kieselgelen untersucht. Die Filterkuchenbildung der KCl-haltigen Suspensionen erfolgt in einer Drucknutsche nach VDI-2762-2. Die Filterkuchen werden über einen perforierten Stempel mit entionisiertem Wasser durchströmt und der Wascherfolg über die Bilanzierung der K+-Ionen ermittelt. Die Porosität der Kieselgel-Filterkuchen beträgt 80 %, wobei sich 50 % der gesamten Mutterlauge in den Innenporen befindet. Dennoch zeigen sich mit 1 % Restbeladung ähnliche Waschergebnisse wie für unporöse Feststoffe (Quarz und Glas). Die Innenporen werden gereinigt, der in der Literatur postulierte ausgeprägte Diffusionsbereich in der Waschkurve wird nicht sichtbar. Berechnungen nach CARMAN-KOZENY, FICK und mittels dimensionsloser Kennzahlen verdeutlichen, dass Perfusion und Diffusion die Wäsche poröser Systeme beeinflussen. Die vorgestellten Modelle eignen sich auch für die Anwendung in der Praxis. / The displacement washing of filter cakes consisting of porous particles is investigated using macro- and mesoporous silica gels. The filter cakes of KCl-containing suspensions are formed in a pressure filter device according to VDI-2762-2. The filter cakes are flown through with deionized water via a perforated piston and the washing success is determined by balancing the K+ ions. The porosity of the silica gel filter cakes is 80 % and 50 % of the mother liquor is trapped in the inner pores. Nevertheless, with 1 % residual loading, washing results are similar to those for non-porous solids (quartz, glass). The inner pores are cleaned, the distinct diffusion region in the washing curve postulated in the literature is not visible. Calculations according to CARMAN-KOZENY, FICK and by means of dimensionless quantities illustrate that both perfusion and diffusion influence the washing of porous systems. The presented models are also suitable for practical applications.

Abstract Food sustainability depends significantly on packaging since it helps maintainfood safe and fresh throughout its shelf life, resulting in the least amount ofwaste and the least negative environmental impact. The main objective of thisstudy is to determine the adsorbed and released amount of antimicrobial agents(benzoic acid and thymol) on modified calcium carbonate (MCC) by investigating adsorption isotherm at 25°C and desorption kinetics at both 22°C and5°C of anti-microbial to identify potential solutions to enhance the long-termsustainability of fresh products such as meat. These agents were incorporatedinto specialized food pads to mitigate bacterial growth in food packaging instead of being directly added to the food. Additionally, the study aimed to determine the amount of carbon dioxide generated when MCC, used as an adsorbent in combination with citric acid, comes into contact with the meat liquid,as this has an impact on the growth of aerobic microorganisms.The findings revealed that MCC adsorbed 44% and 55% of the initial quantities of benzoic acid (BA) and thymol, respectively. Furthermore, after 12 seconds from an initial adsorption amount of 19 mg/g, the maximum amount ofthymol released from MCC was measured at 0.120 mg/ml (approximately0.126%). Similarly, for an initial adsorption amount of 15 mg/g, the quantityof BA released was found to be 0.080 mg/ml (approximately 0.106%). TheUV-spectrophotometer was utilized to determine the amounts of adsorbed anddesorbed anti-microbial agents, while Checkmate 3 was used to assess the release of carbon dioxide.Significantly, the utilization of food pads demonstrated a significant enhancement in the release of carbon dioxide. Interestingly, the presence of anti-microbial agents did not have any influence on the generation of carbon dioxide.This research provides valuable insights into the potential application of foodpads and MCC as effective strategies for preserving fresh meat products bycontrolling microbial activity and promoting sustainability. / Sammanfattning Livsmedelshållbarhet beror i hög grad på förpackningar eftersom det hjälpertill att hålla maten säker och fräsch under hela dess hållbarhetstid, vilket resulterar i minskad mängd avfall och mindre negativ miljöpåverkan. Huvudsyftetmed denna studie var att bestämma den adsorberade och frigjorda mängdenantimikrobiella medel (bensoesyra och tymol) på modifierat kalciumkarbonat(MCC) genom att undersöka adsorptionsisoterm vid 25°C och desorptionskinetiken vid både 22°C och 5 °C av antimikrobiellt medel för att identifierapotentiella lösningar för att förbättra den långsiktiga hållbarheten för färskaprodukter som kött. Dessa medel inkorporerades i specialiserade food pad föratt mildra bakterietillväxt i livsmedelsförpackningar istället för att läggas direkt till maten. Dessutom syftade studien till att fastställa mängden koldioxidsom genereras när MCC, som används som adsorbent i kombination med citronsyra, kommer i kontakt med köttvätskan, eftersom detta har en inverkan påtillväxten av aeroba mikroorganismer.Resultaten visade att MCC adsorberade 44 % och 55 % av de initiala mängderna bensoesyra (BA) respektive tymol. Vidare, efter 12 sekunder från eninitial adsorptionsmängd på 19 mg/g, mättes den maximala mängden tymolsom frigjordes från MCC till 0,120 mg/ml (ungefär 0,126%). På liknande sätt,för en initial adsorptionsmängd på 15 mg/g, visade sig mängden frisatt BA vara0,080 mg/ml (ungefär 0,106%). UV-spektrofotometern användes för att bestämma mängderna av adsorberade och desorberade antimikrobiella medel,medan Checkmate 3 användes för att bedöma frisättningen av koldioxid.Betecknande nog visade användningen av food pad betydande förbättring avutsläppet av koldioxid. Intressant nog har närvaron av antimikrobiella medelinte haft någon inverkan på genereringen av koldioxid. Denna forskning gervärdefulla insikter om den potentiella tillämpningen av food pad och MCC someffektiva strategier för att bevara färska köttprodukter genom att kontrolleramikrobiell aktivitet och främja hållbarhet.