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A microchannel-based thermal management system for hydrogen storage adsorbent bedsSteigleder, Leif J. 14 June 2012 (has links)
Hydrogen has been shown to be a promising replacement for fossil fuels for use in light duty vehicles because it is a clean, renewable and plentiful resource with a high gravimetric energy density. However, in order to obtain an acceptable volumetric energy density, densification of the hydrogen is required. Adsorptive materials have been shown in the literature to increase volumetric and gravimetric storage densities. A major issue with adsorptive storage is that the adsorption process generates heat and optimal storage conditions are at temperatures below 100 K at pressures up to 50 atm. There is a need to develop heat exchanging architecture that enables adsorbents to be a viable method for hydrogen storage by managing the thermal environment of the storage tank.
Based on previous modeling efforts to determine an acceptable bed module height for removal of heat via microchannel cooling plates, a thermal management system has been designed and tested capable of removing the heat of adsorption within adsorbent-filled hydrogen storage tanks. The system uses liquid nitrogen cooling to maintain tank temperatures of below 80 K at 50 atm. System studies show that the microchannel architecture offers a high cooling capacity with about a 6% displacement volume. Simulations and experiments have been conducted to evaluate the design for the cooling capacity, pressure drop, and flow distribution between and across the cooling plates, stress due to the pressurized environment, and thermal stress. Cost models have been developed to demonstrate that the system can be manufactured for a reasonable cost at high production volumes. Experimental results show that the modular system offers an acceptable cooling capacity and pressure drop with good flow distribution while adequately managing thermal stresses during operation. / Graduation date: 2013
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Garlic (Allium Sativum) Agglutinin I: Specificity, Binding And Folding MechanismBachhawat, Kiran 11 1900 (has links)
Lectins are a class of proteins that bind to carbohydrates with a high degree of specificity. They are involved in various cellular processes such as, host - pathogen interactions, targeting of proteins within cells, cell - cell interaction, cellular segregation and development. They serve as important tools for probing the carbohydrate structures in biological systems such as cell membranes and also as model systems for elucidating protein - carbohydrate interactions. Lectins are distributed ubiquitously in nature ranging from microorganisms to the plants and animals.
Plant lectins are a group of proteins that according to a recently updated definition comprise all plant proteins possessing at least one non-catalytic domain that binds reversibly to specific mono- or oligosaccharide. The majority of all currently known plant lectins may be classified into four major groups - (1) Legume lectins, (2) Chitin-binding lectins, (3) Type 2 Ribosome inactivating proteins and the (4) Monocot mannose binding lectins.
The monocot mannose binding lectins are an extended superfamily of structurally and evolutionarily related proteins. Till now these proteins have been isolated from the following families, namely, Amaryllidaceae, Affiaceae, Araceae, Orchidaceae, Iridaceae and Li/iaceae. They exhibit marked sequence homology and a unique specificity for mannose. At present there is a wide interest in the monocot mannose-binding lectins because of: (1) their exclusive specificity towards mannose, (2) their anti - retroviral activity and (3) their potent entomotoxic properties. Of particular interest are lectins from the bulbs of garlic (Allium sativum) and ramson (A. ursinum), which contain more than one type of lectin. The first report of the presence of lectins in the bulbs of garlic {Allium sativum agglutinin, ASA) was made by Van Damme et al in 1991. Bulbs of garlic are
known to accumulate two types of mannose binding lectins, the heterodimeric, ASAI and the hornodimeric, ASAII. Though these two lectins differ in the lengths of their polypeptide chains, they exhibit marked similarities with respect to their primary sequence, post translational modifications, serological properties, immunochemical attributes as well as carbohydrate binding properties.
This thesis describes the successful cloning of the ASAI gene from the garlic genomic DNA and expression of the functional recombinant protein in insect cell lines. ASAI was subsequently characterized for its carbohydrate binding specificity by means of a sensitive enzyme based assay. Finer insights into this sugar binding topology of ASAI for its complementary ligands was obtained from the surface plasmon resonance studies. Lastly, the folding behaviour as well as an estimate of its conformational stability was investigated by differential scanning calorimetric and equilibrium solution denaturation studies.
Chapter 1 provides a comprehensive review on lectins pertaining to their definition, historical background, occurrence in nature, three dimensional structure and architecture, modes of bonding, biological functions and implications as well as their applications in biomedical research.
Chapter 2 describes the isolation and purification of the heterodimeric lectin, ASAI in two steps using affinity chromatography followed by gel filtration chromatography from the bulbs of garlic. The purified ASAI was then characterized for their serological, physico- and immuno-chemical properties by means of capillary electrophoresis, hemagglutination activity and generation of antisera against ASAI in rabbits.
Chapter 3 revolves around the cloning of the gene encoding ASAI by PCR amplification from garlic genomic DNA. The authenticity of the ASA gene was
established by means of gene sequencing, which in turn provided us with the primary sequence of this lectin. With the ASAI clone established innumerable attempts, as highlighted in the chapter, were made to express the functional protein in bacteria. All attempts yielded pure recombinant garlic lectin with no detectable activity. This prompted us to shift our efforts into expression of the recombinant protein in the baculovirus expression system using the Sf21 insect cell lines and the Autographa californica nuclear polyhedrosis virus (AcNPV). The choice of this system proved beneficial as we obtained functional recombinant garlic lectin with its hemagglutinating activity comparable to the native protein.
Chapter 4 highlights the design of an elegant coupled enzyme-based colorimetric assay (Enzyme Linked Lectin Adsorbent Assay) for elucidation of the carbohydrate binding specificity of ASAI. This expansive and extensive study involved the assay of a wide range of mannooligosaccharides in order to gain an insight into the sugar binding details of ASAI. ASAI recognizes monosaccharides in the mannosyl configuration. The potencies of the ligands for ASAI is shown to increase in the following order: Mannobiose < Mannotriose Mannopentaose Man9 oligosaccharide. Mannononase glycopeptide (Man9GlcNAc2Asn), the highest oligomer studied exhibited the greatest binding affinity suggesting ASAI to possess a preference for cluster of terminal αl-2-linked mannosyl residues at the non-reducing end. This kind of exquisite specificity is unique in the lectins described so far. Among the glycoproteins assayed, invertase, soyabean agglutinin and ovalbumin displayed high binding affinity.
Chapter 5 unravels the fine specificity of the mannose containing carbohydrate moieties for binding to ASAI with emphasis on their kinetics of binding. This has been achieved by invoking the principle of surface plasmon resonance allowing measurement of bimolecular interactions in real time. This investigation corroborates our earlier study about the special preference of garlic lectin for terminal a α1-2 linked mannose residues. Increase in binding propensity can be directly correlated to the addition of αl-2 linked mannose to the mannooligosaccharide at its non-reducing end. An analyses of these data reveals that the α1-2 linked terminal mannose on the α1-6 arm to be the critical determinant in the recognition of mannooligosaccharides by the lectin. While kI increases progressively from Man3 to Man7 derivatives, and more dramatically so for Man8 and Man9 derivatives, k-1 decreases relatively much less gradually from Man3 to Man9 structures. An unprecedented increase in the association rate constant for interaction with ASAI with the structure of the oligosaccharide ligand constitutes a significant finding in protein-sugar recognition.
Chapter 6 deals with the thermal unfolding of ASAI, characterized by differential scanning calorimetry and circular dichroism which shows it to be highly reversible and can be defined as a two-state process in which the folded dimer is converted directly to the unfolded monomers (A2 2U). Moreover, its conformational stability has been determined as a function of temperature; GdnCl concentration and pH using a combination of thermal and isothermal GdnCl induced unfolding monitored by DSC, far-UV CD and fluorescence, respectively. Analysis of these data yielded the heat capacity change upon unfolding (∆CP) as also the temperature dependence of the thermodynamic parameters, namely, ∆G, ∆H, ∆S. The protein appears to attain a completely unfolded state irrespective of the method of denaturation. The absence of any folding intermediates suggests the quaternary interactions to be the major contributor to the conformational stability of the protein, which correlates very well with its X-ray structure. The final chapter summarizes the findings reported in the thesis.
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Magnetická modifikace mikrobiálních buněk / Magnetic modification of microbial cellsBALDÍKOVÁ, Eva January 2013 (has links)
Baker´s yeast (Saccharomyces cerevisiae) were magnetically modified by three different methods, namely, surface modification by magnetic fluid, entrapment of cells into alginate and covalent immobilization on particles of magnetic chitosan. The ability of H2O2 decomposition was tested for all types of modification. It is apparent that the most amount of hydrogen peroxid was degraded by magnetic fluid - modified cells (84-95%), while the efficiency of cell which were modified by other methods was much lower (40-60%). Thanks to immobilization on particles of magnetic chitosan, we made completely new type of magnetic material, which was tested for adsorption of Crystal violet and Safranin O. It was founded that magnetic chitosan adsorbs no dyes, so all adsorption belongs to immobilized yeast. The maximum adsorption capacities were determined using Langmuire isotherm at 69,4 mg/g for Crystal violet and 99,0 mg/g for Safranin O.
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Estudo do bagaço de cevada e da palha de milho como materiais adsorventes alternativos para remoção do agrotóxico carbaril de meio aquoso contaminado / Study of barley bagasse and corn straw as alternative adsorbent materials for the removal of the carbaryl pesticide from contaminated aqueous mediumMilhomem, Karoline Pinto 17 August 2018 (has links)
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Previous issue date: 2018-08-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this dissertation, the materials corn straw and barley bagasse were investigated as
alternative adsorbents for removal of the carbaryl pesticide from aqueous medium. For
this, both materials were ground to obtain uniform particles (granulometry between 20 and
48 mesh) and treated with hydrated ethyl alcohol. The quantification of the carbaryl
pesticide was made by High Efficiency Liquid Chromatography with UV-vis detector. The
values of LD and LQ for the determination of the carbaryl pesticide by liquid
chromatography using the method used were 0.01 mg L-1 and 0.10 mg L-1, respectively.
The characterization of the adsorbent materials by FTIR showed the presence of the
functional groups: hydroxyl, carbonyl and methyl, very common in lignocellulosic
materials. The pH at the zero loading point (pHPCZ) was 7.08 for barley bagasse and 6.44
for corn straw. The adsorption capacity of the investigated materials was evaluated under
different parameters such as material dose (g L-1), contact time between the pesticide
solution and the adsorbent material (min) and the concentration of the pesticide in the
solution (mg L-1). An alternative adsorption procedure was also proposed with the
adsorbents packaged in a column where different doses of the adsorbents were
evaluated and finally the adsorption process was evaluated using natural water samples.
From the study of the dose of the materials the dose of 20 g L-1, equivalent to 200 mg of
the adsorbent material in 10 mL of solution was selected, where 45.1% of the carbaryl
was obtained when the barley bagasse was used and 49.2% when corn straw was used.
For both adsorbents the kinetic study showed that the adsorption of the carbaryl
agrochemical is best represented by the Avrami kinetic model, indicating that the
adsorption of the carbaryl is not constant, but follows multiple orders. The maximum
adsorption capacity (Qmax) was obtained by the construction of adsorption isotherms,
where it was verified that the experimental data of the process of adsorption of the
carbaryl by the barley bagasse is better represented by the Langmuir model providing a
value of Qmax of 6, 5244 mg g-1. For corn straw, the Sips model was the most adequate
with a Qmax value of 1.2625 mg g -1. In the column adsorption procedure the barley
bagasse was efficient in all the doses evaluated, obtaining practically the same rate of
removal as the procedure performed in batch mode, however in a much shorter time. As
for the adsorbent corn straw, the removal through the column procedure was much less
effective, suggesting that for this material the batch procedure is more adequate. In the
adsorption study using natural water samples as an aqueous matrix, it was verified that
the adsorption process of the carbaryl by both adsorbents can be affected by the pH of
the medium and also by the presence of other compounds present in the aqueous matrix.
In general, the results indicate that the barleybagasse and corn straw materials can be
used as adsorbent materials in the treatment of aqueous medium contaminated with the
carbaryl pesticide. / Nesta dissertação, os materiais palha de milho e bagaço de cevada foram investigados como
adsorventes alternativos para remoção do agrotóxico carbaril de meio aquoso. Para isso, ambos
materiais foram triturados para obtenção de partículas uniformes (granulometria entre 20 e 48
mesh) e tratados com álcool etílico hidratado. A quantificação do agrotóxico carbaril foi feita por
Cromatografia Líquida de Alta Eficiência com detector UV-vis. Os valores de LD e LQ para a
determinação do agrotóxico carbaril por cromatografia líquida, através do método empregado,
foram 0,01 mg L-1 e 0,10 mg L-1, respectivamente. A caracterização dos materiais adsorventes
por FTIR mostrou a presença dos grupos funcionais: hidroxila, carbonila e metila, bastante
comuns em materiais lignocelulósicos. O pH no ponto de carga zero (pHPCZ) foi 7,08 para o
bagaço de cevada e 6,44 para a palha de milho. A capacidade de adsorção dos materiais
investigados foi avaliada sob diferentes parâmetros como dose do material (g L-1), tempo de
contato entre a solução do agrotóxico e o material adsorvente (min) e a concentração do
agrotóxico na solução (mg L-1). Foi proposto também um procedimento alternativo de adsorção
com os adsorventes empacotados em uma coluna onde avaliou-se diferentes doses dos
adsorventes e por fim avaliou-se o processo de adsorção utilizando amostras de água natural. A
partir do estudo da dose dos materiais foi selecionada a dose de 20 g L-1, equivalente a 200 mg
do material adsorvente em 10 mL de solução, onde foi obtida remoção de 45,1% do carbaril
quando foi utilizado o bagaço de cevada e 49,2% quando foi usada a palha de milho. Para ambos
os adsorventes o estudo cinético mostrou que a adsorção do agrotóxico carbaril é melhor
representada pelo modelo cinético de Avrami, indicando que a adsorção do carbaril não é
constante, mas segue múltiplas ordens. A capacidade máxima de adsorção (Qmáx) foi obtida
pela construção de isotermas de adsorção, onde verificou-se que os dados experimentais do
processo de adsorção do carbaril pelo bagaço de cevada é mais bem representado pelo modelo
de Langmuir fornecendo um valor de Qmáx de 6,5244 mg g-1. Já para a palha de milho o modelo
de Sips mostrou-se o mais adequado com um valor Qmáx de 1,2625 mg g-1. No procedimento de
adsorção em coluna o bagaço de cevada mostrou-se eficiente em todas as doses avaliadas,
obtendo praticamente a mesma taxa de remoção que o procedimento realizado em modo
batelada, no entanto em um tempo bem menor. Já para o adsorvente palha de milho, a remoção
através do procedimento em coluna foi bem menos efetiva, sugerindo que para este material o
procedimento em batelada é mais adequado. No estudo de adsorção utilizando amostras de
água natural como matriz aquosa, verificou-se que o processo de adsorção do carbaril por ambos
os adsorventes pode ser afetado pelo pH do meio e também pela presença de outros compostos
presentes na matriz aquosa. De um modo geral os resultados obtidos indicam que os materiais
bagaço de cevada e palha de milho podem ser utilizados como materiais adsorventes no
tratamento de meio aquoso contaminado com o agrotóxico carbaril.
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Estudo da typha angustifolia l. como material vegetal adsorvente para a remoção dos agrotóxicos trifluralina, clorpirifós e α-endossulfam de meio aquoso / A study of the typha angustifolia l. as plant material adsorbent for removal of pesticides trifluralin, chlorpyriphos and α-endosulfan in aqueous mediumMendes, Marcia Felipe 26 February 2016 (has links)
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Previous issue date: 2016-02-26 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Because of the toxicological relevance of pesticides introduced into the environment through
agricultural practices, it is necessary to develop simple methodologies with low cost, enabling
remove these pollutants from the environment, in particular of water intended for human
consumption. The adsorption process is an efficient and low cost technique that have wide
application. The adsorbent capacity of the leaves of Typha angustifolia L. herbaceous perennial
plant belonging to the family Typhaceae, in Brazil it is also popularly known as taboa, was
investigated for the removal of pesticides trifluralin, chlorpyrifos and α-endosulfan from
aqueous medium. The the analytical method using solid phase extraction (SPE) and
chromatography with electron capture detector (GC/ECD) was optimizates and validate. The
validation criterions were reached and the analytical methos was considered efficient for
trifluralin, chlorpyrifos and α-endosulfan quantification in an aqueous medium, providing
credibility to the results obtained in the adsorption experiments. The adsorption capacity of T.
angustifolia was evaluated under different parameters: treatment of the material, amount of
material, contact time between the plant material and the pesticides solution and
concentration of the pesticides solution. The results showed that treatment of the material
with distilled water and was satisfactory and, for all doses evaluated the pesticide removal
was efficient, with best results obtained at a dose of 3.0 g L-1
, equivalent to 60 mg of adsorbent
in 20.0 mL of solution, in which the pesticide removal were between 73 and 80%. The
adsorption kinetics of the pesticide by T. angustifolia showed that the adsorption equilibrium
was reached in 40 minutes for all pesticides, removing up to 90% and using a very small
amount of plant material (3 g L-1
). The experimental data were evaluated using the kinetic
models of pseudo-first order, pseudo-second order and Avrami. One of the limitations
encountered in the concentration influence study is the limited solubility of the agrochemical
in aqueous medium (between 0.33 and 1.00 mg L-1
), resulting in the study of a small
concentration range in the adsorption experiments. To study the pesticides adsorption
mechanism by T. angustifolia material, the experimental data were applied to Langmuir,
Freundlich and Sips non-linear isotherms models. Additional tests showed that the adsorption
capacity is unaffected when using natural water in the adsorption experiments. The results
indicate that the material obtained from of T. angustifolia leaves, has a great potential to be
used as an alternative adsorbent material in pesticide contaminated aqueous solution
treatment. / Devido à relevância toxicológica dos agrotóxicos introduzidos no ambiente através de práticas
agrícolas, torna-se necessário o desenvolvimento de metodologias simples e de baixo custo,
que permitam remover esses poluentes do meio ambiente, em especial, das águas destinadas
a consumo humano. O processo de adsorção é uma técnica que possui grande aplicação, por
ser eficiente e de baixo custo. A capacidade adsorvente das folhas de Typha angustifolia L.,
planta herbácea perene pertencente à família Typhaceae, no Brasil também conhecida
popularmente como taboa, foi investigada para a remoção dos agrotóxicos trifluralina,
clorpirifós e α-endossulfam de meio aquoso. Foi realizada a otimização e validação da
metodologia analítica de extração em fase sólida (SPE) e determinação por cromatografia
gasosa utilizando-se o detector por captura de elétrons (GC/ECD). A metodologia (SPEGC/ECD)
atendeu aos critérios de validação estabelecidos e foi eficiente para a quantificação
dos agrotóxicos em meio aquoso, fornecendo credibilidade aos resultados obtidos nos ensaios
de adsorção. A capacidade de adsorção da T. angustifolia foi avaliada sob diferentes
parâmetros: tratamento do material, dose de material, tempo de contato entre o material
vegetal e a solução dos agrotóxicos e concentração dos agrotóxicos na solução. Os resultados
obtidos mostraram que o tratamento do material com água destilada foi satisfatório e que
para todas as doses de adsorvente avaliadas a remoção dos agrotóxicos foi eficiente, sendo
obtido um melhor resultado para a dose de 3,0 g L-1
, equivalente a 60 mg de adsorvente para
20,00 mL de solução, onde se obteve remoção entre 73 e 80% dos agrotóxicos. O estudo
cinético do processo de adsorção dos agrotóxicos pela T. angustifolia mostrou que o equilíbrio
de adsorção foi alcançado em 40 minutos, para todos os agrotóxicos, com remoção de até
90%, utilizando uma dose muito pequena de material vegetal (3 g L-1
). Os dados
experimentais foram avaliados utilizando-se os modelos cinéticos de pseudo-primeira ordem,
pseudo-segunda ordem e Avrami. Uma das limitações encontradas no estudo da influência da
concentração foi a solubilidade limitada dos agrotóxicos em meio aquoso (entre 0,33 e 1,00
mg L-1
), que fez com que os ensaios de adsorção fossem avaliados para uma pequena faixa
de concentração. Para estudar o mecanismo de adsorção dos agrotóxicos pelo material T.
angustifolia, os dados experimentais foram aplicados aos modelos não lineares de Langmuir,
Freundlich e Sips. Ensaios adicionais mostraram que a capacidade de adsorção é pouco afetada
quando se utiliza água natural obtida em represas nos ensaios de adsorção. Os resultados
obtidos indicam que o material vegetal, obtido a partir das folhas de T. angustifolia, possui
um grande potencial para ser utilizado como material adsorvente alternativo no tratamento
de meio aquoso contaminado com os agrotóxicos trifluralina, clorpirifós e α-endossulfam.
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"A utilização de turfa como adsorvente de metais pesados. O exemplo da contaminação da Bacia do Rio Ribeira de Iguape por chumbo e metais associados" / "The utilization of peat as heavy metal adsorbent. The example of the contamination of Ribeira do Iguape River catchment by lead and associated minerals"José Guilherme Franchi 19 November 2004 (has links)
Este trabalho teve como objetivos principais a caracterização da mina de turfa de Eugênio de Melo, localizada no Estado de São Paulo, região do Vale do Rio Paraíba do Sul, bem como uma amostra representativa do seu minério. Esta amostra foi testada sob duas condições in natura e tratada com ácido clorídrico como adsorvente de metais pesados visando a aplicação do minério em processos de tratamento de efluentes líquidos. Adotaram-se como estudos de caso lixívias obtidas a partir de resíduos da mineração de sulfetos de chumbo e metais associados existentes na região do alto curso do Rio Ribeira de Iguape, geradas em laboratório. Tais depósitos encontram-se sob a forma de extensos corpos às margens de importantes drenagens, circunscritas à região de Adrianópolis (PR). A possibilidade de liberação dos metais pesados presentes nestes depósitos para o ambiente foi avaliada através de estudos granulométricos, mineralógicos e químicos de uma coluna amostrada num destes depósitos. Os teores dos metais presentes nas lixívias enquadraram-nas como não passíveis de descarte para o ambiente sem tratamento prévio, segundo a legislação estadual e federal que regem o assunto. Os resíduos da mineração aqui estudados, compreendendo rejeitos das plantas de concentração mineral e escórias de uma unidade de metalurgia, foram caracterizados como Classe I (perigosos) de acordo com metodologia adotada pela Associação Brasileira de Normas Técnicas. A capacidade adsortiva da turfa para 5 dos metais presentes nas lixívias foi avaliada através de experimentos de equilíbrio, conduzidos em batelada, em sistemas de componente único. Os dados obtidos apresentaram ajuste ao modelo cinético de Langmuir. A afinidade química da turfa revelou-se mais forte para chumbo, cobre e cádmio, e mais reduzida para zinco e manganês. Cálcio e magnésio, provenientes dos metadolomitos hospedeiros das mineralizações sulfetadas, apresentam-se em grande quantidade nas lixívias e foram caracterizados como elementos interferentes no processo adsortivo, que se mostrou, também, influenciado pelo pH e temperatura de realização dos ensaios. As lixívias foram submetidas a 5 ciclos sucessivos de contato com a turfa para se avaliar a eficiência do processo adsortivo em enquadrá-las à legislação ambiental de descarte. Nesta simulação de tratamento de efluentes por bateladas, em situação de adsorção competitiva, a turfa revelou-se um bom adsorvedor para chumbo e cobre. Seu modesto desempenho relativamente a cádmio, zinco e manganês posiciona-a como insumo adequado a processos de descontaminação de efluentes líquidos preferencialmente após etapa de tratamento primário. / This work has as main objectives the characterization of the Eugênio de Melo peat mine, located in the Paraíba do Sul River Valley, State of São Paulo, as well as a representative sample of its ore. This sample was tested as an absorbent material in two conditions both in natura and treated with hydrochloric acid in order to assess its use in liquid effluent treatment process. It were adopted as case studies lab generated leaches obtained from mining residues of lead and associated metals sulfides present at the upper course of the Ribeira do Iguape River region, accumulated as huge deposits close to important drainages, near the Adrianópolis (PR) region. The possibility of the heavy metals environmental release from those deposits was assessed through grain size distribution, mineralogical and chemical approaches. These studies were led in a vertical profile surveyed in a specified deposit. The leaches heavy metal contents surpass the limits set by both state and federal environmental permits, so they are not allowed for discharge to the environment without prior treatment. The mining residues studied here mining wastes and metallurgical slags were characterized as Type I (perilous material) according to Brazilian Guidelines for Residues Classification set by Brazilian Association for Technical Standards. The peats adsorptive capacity was assessed for 5 of the heavy metals present in the leaches by means of batch equilibrium essays conducted in single component systems. The data of these experiments fitted to Langmuirs kinetic model. The chemical affinity of the peat was stronger for lead, copper and cadmium, and weaker for zinc and manganese. Calcium and magnesium derived from metadolomites that hosts sulfide mineralization are in great amount in the leaches. They were identified as interferential constituents to the adsorptive process, which are also affected by the pH and temperature of the assays. The leaches were undergone to 5 cycles of contact with peat in order to assess if the adsorptive process fit them to the legal discharge environmental standards. In this simulation of batch effluent treatment by means of competitive adsorption, the peat revealed itself as a good adsorbent for both lead and copper. The weak adsorptive performance for cadmium, zinc and manganese ranked peat only as a qualified supplies to remediation process entailing liquid effluents, preferably after primary treatment process.
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Preparo de biomassas vegetais modificadas quimicamente e aplicação em estudos adsortivos de Cd(II), Pb (II) E Cr (III) / Preparation of chemically modified plant biomasses and application in adsorption studies of Cd(II), Pb(II) and Cr (III)Schwantes, Daniel 05 August 2016 (has links)
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Previous issue date: 2016-08-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research relates the development and use of modified adsorbents from agroindustrial residues. The following solid agroindustrial residues were obtained: pine bark (Pinus elliottii), solid residue from the manufacture of wood; Crambe cake (Crambe abyssinica Hochst), solid residue from oil extraction (biodiesel agroindustry); and cassava peels (Manihot esculenta Crantz), a byproduct of cassava industrialization. Biosorbents P. in natura, C. in natura and M. in natura (natural adsorbents or biosorbents) were produced from these agroindustrial residues, which had no or low market value, from which were produced the modified adsorbents, by washing the biomass with solutions of H2O2, H2SO4 and NaOH 0.1 mol L-1, resulting the modified adsorbents of pinus P. H2O2, P. H2SO4 and P. NaOH; crambe C. H2O2, C. H2SO4 and C. NaOH, and cassava M. H2O2, M. H2SO4, M. NaOH. In the first step of the study of these adsorbents (in natura and modified) the adsorbent materials were characterized, namely: chemical composition of the adsorbents, pHPCZ, infrared spectra (FT-IR), scanning electron microscopy (SEM), thermogravimetry (TG and DTG), BET and BJH isotherms (porosity and surface area). After the characterization of the adsorbent materials, adsorption studies were carried out for the evalution of Cd(II), Pb(II) and Cr(III) removal, which aimed to evaluate the performance of the materials on the influence of the pH of contaminant solution (ideal adsorption conditions), ie, the adsorption of metal ions as a function of increasing masses and the pH of the medium; the influence of adsorption time (adsorption kinetics), the influence of increasing concentrations of metal ions and isotherm linearization (adsorption equilibrium studies), the effect of temperature on the sorption process (adsorption studies) as well as the reuse of these adsorbent materials by acid elution (desorption studies). The scanning electron microscopes indicated changes in the adsorbents surface; the pHPZC of the modified adsorbents was distinct from the biosorbents. In addition, changes were also observed in the bands of the functional groups in the infrared spectrum, with new functional groups observed, such data indicate that modifications occurred to the adsorbents as a function of the chemical treatment applied. The results showed that, in general, the modified adsorbents present higher adsorption capacity of Cd(II), Pb(II) and Cr(III) metal ions than in natura materials. The modified adsorbents based on pinus, crambe and cassava did not show significant variation in relation to the studied pH range, which is a great advantage, because the adsorbents developed adapt to a wide pH range of contaminated water. An average time of 40 minutes was found for adsorption equilibrium, indicating that the sorption process is fast and occurs in the first few moments. The adsorption of the toxic ions occurs in mono and multilayer, in agreement with the good adjustments observed for Langmuir and Freundlich. In general, the adsorbents presented good reuse capacities, except when used for Cr(III) adsorption, because in this case it is difficult to reuse the adsorbents due to the low desorption rates of this metal, possibly due to chemisorption. Based on the results obtained, it can be concluded that the adsorbents of pinus, crambe and cassava present themselves as excellent, renewable, high availability and low cost, being an attractive alternative for the industry, through its use in advanced treatment systems, for the removal of metals such as Cd(II), Pb(II) and Cr(III) / Esta pesquisa relaciona o desenvolvimento e uso de adsorventes modificados a partir de resíduos agroindustriais. Para tal, foram obtidos os seguintes resíduos sólidos agroindustriais: cascas de pinus (Pinus elliottii), resíduo sólido da fabricação de madeira; torta de crambe (Crambe abyssinica Hochst), resíduo sólido da extração do óleo (agroindústria do biodiesel); e cascas de mandioca (Manihot esculenta Crantz), subproduto da industrialização da mandioca. A partir destes resíduos agroindustriais, que apresentam nenhum ou baixo valor de mercado, foram produzidos os biossorventes P. in natura, C. in natura e M. in natura e (adsorventes naturais ou biossorventes), dos quais foram produzidos os adsorventes modificados, por meio da lavagem com soluções de H2O2, H2SO4 e NaOH 0,1 mol L-1, dando origem aos adsorventes modificados de pinus P. H2O2, P. H2SO4 e P. NaOH; de crambe C. H2O2, C. H2SO4 e C. NaOH, e de mandioca M. H2O2, M. H2SO4, M. NaOH. Na primeira etapa do estudo destes adsorventes (in natura e modificados), realizou-se a caracterização dos materiais, a citar: composição química dos adsorventes, pHPCZ, espectros de infravermelho (FT-IR), microscopia eletrônica de varredura (MEV), termogravimetria (TG e DTG) e isotermas de BET e BJH (porosidade e área superficial). Após a caracterização dos materiais adsorventes, foram conduzidos estudos de adsorção para os metais Cd(II), Pb(II) e Cr(III), que visavam avaliar a performance dos materiais quanto a influência do pH da solução contaminante (condições ideais de adsorção), ou seja, a adsorção de íons metálicos em função de massas crescentes e do pH do meio; o efeito do tempo no processo de adsorção (cinética de adsorção), a influência de concentrações crescentes de íons metálicos e linearização das isotermas (estudos de equilíbrio de adsorção), o efeito da temperatura no processo sortivo (estudos de termodinâmica de adsorção), bem como o reuso destes materiais adsorventes por meio de eluição ácida (estudos de dessorção). As microscopias eletrônicas de varredura indicaram a ocorrência de mudanças na superfície dos adsorventes, o pHPCZ dos adsorventes modificados foi distinto dos biossorventes, além disso, também foram observadas alterações quanto a amplitude das bandas dos grupos funcionais no espectro de infravermelho, com novos grupos funcionais observados, tais dados sugerem a ocorrência de modificações aos adsorventes. Os resultados obtidos demonstram que, no geral, os adsorventes modificados apresentam maior capacidade de adsorção de íons metálicos Cd(II), Pb(II) e Cr(III) que os materiais in natura. Os adsorventes a base de pinus, crambe e mandioca não apresentaram variação significativa com relação à faixa de pH estudada, sendo esta uma grande vantagem, pois os adsorventes desenvolvidos se adaptam a uma ampla faixa de pH de águas contaminadas. Foi encontrado um tempo médio de 40 minutos para ocorrência do equilíbrio de adsorção, indicando que o processo sortivo é rápido e ocorre nos primeiros instantes. A adsorção dos íons ocorre em mono e multicamadas, em concordância com os bons ajustes observados para Langmuir e Freundlich. Em geral, os adsorventes apresentaram boa capacidade de reuso, exceto quando utilizados para adsorção de Cr(III), pois neste caso ocorre dificuldade de reuso dos adsorventes pela baixa taxa de dessorção deste metal, indicando possível quimissorção. Pelos resultados obtidos conclui-se que os adsorventes modificados de pinus, crambe e mandioca apresentam-se como excelentes, renováveis, de alta disponibilidade e baixo custo, sendo uma alternativa atraente para a indústria, mediante sua utilização em sistemas de tratamento avançados, para a remoção de metais como Cd(II), Pb(II) e Cr(III)
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Redukovanje sadržaja nesaharoznih jedinjenja u melasi šećerne repe primenom modifikovanih mineralnih i celuloznih adsorbenata / Reduction of non-sugar compounds content in sugar beet molasses by applying modified mineral and cellulosic adsorbentsĐorđević Miljana 25 September 2020 (has links)
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nepoželjnih promena pri skladištenju melase. Stoga je predmet istraživanja ove disertacije redukovanje sadržaja nesaharoznih jedinjenja u melasi šećerne repe upotrebom prirodnih adsorbenata mineralnog (različiti tipovi bentonita) i celuloznog (celuloza različitog stepena čistoće i modifikovani ekstrahovani rezanci šećerne repe) porekla. Variranjem pH vrednosti sredine, suve materije melase i koncentracije primenjenog adsorbenta ispitan je sinergistički efekat uslova tretmana na stepen redukcije sadržaja nesaharoznih jedinjenja u melasi. Efikasnost sprovedenog tretmana utvrđena je na osnovu promena parametara kvaliteta melase i to boje, mutnoće, sadržaja saharoze, sadržaja suve materije i sadržaja pepela. </span></p><p class="MsoNormal" style="text-align:justify"><span lang="EN-US" style="font-size:10.0pt;line-height:115%;font-family:"Cambria","serif";mso-ascii-theme-font:major-latin;mso-hansi-theme-font:major-latin;mso-bidi-font-family:"Times New Roman"">Na osnovu rezultata uočava se da je pozitivan uticaj kombinovanog dejstva upotrebljenih adsorbenata i uslova tretmana najizraženiji kod mutnoće i boje melase što potvrđuje afinitet adsorbenata ka zadržavanju i/ili vezivanju bojenih materija. Takođe, navedeni pozitivan uticaj izražen je u manjoj ili većoj meri u zavisnosti od tipa primenjenog adsorbenta ali i uslova gde je uglavnom dominantan uticaj pH vrednosti </span></p><p><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings></xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:DoNotShowRevisions/> <w:DoNotPrintRevisions/> <w:DoNotShowMarkup/> <w:DoNotShowComments/> <w:DoNotShowInsertionsAndDeletions/> <w:DoNotShowPropertyChanges/> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:EnableOpenTypeKerning/> <w:DontFlipMirrorIndents/> <w:OverrideTableStyleHps/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument></xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true" DefSemiHidden="true" DefQFormat="false" DefPriority="99" LatentStyleCount="267"> <w:LsdException Locked="false" Priority="0" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="Normal"/> <w:LsdException Locked="false" Priority="9" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="heading 1"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 6"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 7"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 8"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 9"/> <w:LsdException Locked="false" Priority="39" Name="toc 1"/> <w:LsdException Locked="false" Priority="39" Name="toc 2"/> <w:LsdException Locked="false" Priority="39" Name="toc 3"/> <w:LsdException Locked="false" Priority="39" Name="toc 4"/> <w:LsdException Locked="false" Priority="39" Name="toc 5"/> <w:LsdException Locked="false" Priority="39" Name="toc 6"/> <w:LsdException Locked="false" Priority="39" Name="toc 7"/> <w:LsdException Locked=&qu / <p> </p><p class="MsoNormal" style="text-align:justify"><span lang="EN-US" style="font-size:10.0pt;line-height:115%;font-family:"Cambria","serif";mso-fareast-font-family:Calibri;mso-bidi-font-family:"Times New Roman"">The application of different treatments aiming to reduce the content of non-sugar compounds in sugar beet molasses is a potential method for molasses quality enhancement, facilitation of molasses desugarization process and prevention of any undesirable changes during molasses storage. Therefore, the objective of this dissertation is to reduce the content of non-sugar compounds in sugar beet molasses by using natural adsorbents of mineral (different types of bentonite) and cellulosic (cellulose of different purity and modified sugar beet pulp) origin. By varying treatment conditions such as pH, molasses dry substance and the applied adsorbent concentration, the synergistic effect of the treatment conditions on the reduction efficiency of non-sugar compounds content in molasses was examined. The treatment effectiveness was determined based on changes in molasses quality parameters, namely color, turbidity, sucrose content, dry substance content and ash content.</span></p><p><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings></xml><![endif]--></p><p><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:DoNotShowRevisions/> <w:DoNotPrintRevisions/> <w:DoNotShowMarkup/> <w:DoNotShowComments/> <w:DoNotShowInsertionsAndDeletions/> <w:DoNotShowPropertyChanges/> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:EnableOpenTypeKerning/> <w:DontFlipMirrorIndents/> <w:OverrideTableStyleHps/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument></xml><![endif]--></p><p class="MsoNormal" style="text-align:justify"><span lang="EN-US" style="font-size:10.0pt;line-height:115%;font-family:"Cambria","serif";mso-fareast-font-family:Calibri;mso-bidi-font-family:"Times New Roman"">According to the obtained results, the positive influence of the combined effect of applied adsorbents and treatment conditions is most pronounced for molasses quality parameters turbidity and colour, which confirms the applied adsorbents affinity towards coloured compounds retention or binding. Also, the stated positive influence is expressed to a greater or lesser extent depending on the type of adsorbent used as well as the conditions applied, where the influence of pH is mainly dominant.</span></p><p><!--[if gte mso 10]><style> /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-parent:"";mso-padding-alt:0cm 5.4pt 0cm 5.4pt;mso-para-margin-top:0cm;mso-para-margin-right:0cm;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0cm;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:"Calibri","sans-serif";mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;}</style><![endif]--></p><p><!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> 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[pt] ADSORVENTES À BASE DE SÍLICA GEL MODIFICADA COM DERIVADOS DE ÁCIDO FOSFÔNICO, HIDROXÂMICO E PIRIDINOCARBOXÍLICO PARA EXTRAÇÃO EM FASE SÓLIDA DISPERSIVA E SEPARAÇÃO DOS ELEMENTOS TERRAS RARAS / [en] SILICA-BASED ADSORBENTS WITH IMMOBILIZED DERIVATIVES OF PHOSPHONIC, HYDROXAMIC AND PYRIDINECARBOXYLIC ACIDS FOR DISPERSIVE SOLID PHASE EXTRACTION AND SEPARATION OF RARE EARTH ELEMENTSOLENA ARTIUSHENKO 21 May 2020 (has links)
[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.
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Obtenção de filme adsorvente de celulose/SBA-15 para limpeza de superfícies policromadas em obras de arte / Achievement of cellulose/SBA-15 adsorbent film for cleaning polychrome surfaces in works of artRizzo, Marcia de Mathias 11 June 2015 (has links)
O verniz acrílico Paraloid B72TM é um termoplástico que atua como um bom adesivo formando filmes claros. Tem sido usado em conservação e restauração de bens culturais desde os anos 50. Por apresentar Tg próximo a 40°C, no Brasil, algumas substâncias podem ficar adsorvidas à superfície de camadas pictóricas envernizadas. Nesse caso, a limpeza tradicional (palito com algodão e solventes) pode acarretar danos (penetração do solvente, abrasão, etc.) à obra de arte. A limpeza por métodos aquosos (géis e emulsões) pode deixar resíduos que interagem com os materiais originais. Por outro lado, a utilização de nano-géis magnéticos é bastante restrita e de difícil acesso. Esse trabalho tem por objetivo o desenvolvimento de filmes adsorventes de celulose/SBA-15 para retirada do verniz Paraloid B72TM, onde se fizer necessário. Esses filmes foram empregados sobre miméticos (pinturas originais de diferentes técnicas e obras confeccionadas para estudo envernizadas com Paraloid B72TM) para verificação de sua eficácia. As matérias primas, os miméticos e os filmes adsorventes, antes e após a aplicação, foram caracterizadas por técnicas físico-química e analíticas [análise térmica (TG/DTG e DTA); espectroscopia no infravermelho (FTIR); microscopia eletrônica de varredura (MEV); microscopia eletrônica de transmissão (MET); espectroscopia de fluorescência de raios X (XRF), microscopia digital de superfície e estereoscopia]. A microscopia digital de superfície e a estereoscopia foram usadas para inspeção do micro morfologia da superfície e possibilitaram identificar a presença de partículas adsorvidas na superfície das obras. A MEV, a MET permitiram observar a micromorfologia das superfícies e a FTIR caracterizar as matérias primas e os filmes adsorventes. O comportamento térmico das matérias primas e dos filmes adsorventes, antes e após a aplicação, foi avaliado por TG/DTG e DTA. A avaliação dos miméticos e dos filmes de adsorção, antes e depois da aplicação, por XRF evidenciou que não houve danos aos miméticos. O filme de celulose/SBA-15 como adsorvedor da resina acrílica na limpeza de superfícies policromadas em obras de arte, por meio de um solvente, se mostrou eficaz. Esse método é alternativo e não pretende substituir qualquer outro já existente. Visto que, em restauração de obras de arte cada caso é especifico e nada substitui o conhecimento, discernimento e destreza do restaurador. / The acrylic varnish Paraloid B72TM is a thermoplastic, which acts as an adhesive forming clear films. It has been used in conservation and restoration of cultural property since the 50ths. By presenting Tg near 40°C, some substances can become adsorbed on the surface of varnished paintng layers, for example in Brazil. In this case, the traditional cleaning (stick with cotton and solvents) can cause damage (penetration of the solvent, abrasion,...) to the artwork. The cleaning of aqueous methods (gels and emulsions) can leave residues that interact with the original materials. Already, the use of magnetic nano-gels is restricted and difficult to access. This paper aims at developing cellulose/SBA-15 adsorbent films for withdrawal of Paraloid B72TM varnish, where it becomes necessary. These films were employed on mimetic (original paintings of different techniques and works made for study varnished with Paraloid B72TM) to verify its effectiveness. The raw materials, adsorbents and mimetic films before and after application were characterized by physico-chemical and analytical techniques [thermal analysis (TG/DTG and DTA); infrared spectroscopy (FTIR); scanning electron microscopy (SEM); transmited electron microscopy (TEM); fluorescent X-ray spectroscopy (XRF), digital microscopy and surface stereoscopic]. The digital microscopy and surface stereoscopy were used to inspect the surface micro morphology and it was possible to identify the presence of particles adsorbed on the surface of the artwork. The SEM, the TEM showed the micro morphology of the surfaces and FTIR characterized the raw materials and adsorbents films. The thermal behavior of materials and adsorbents films before and after application was evaluated by TG/DTG and DTA. Assessment of adsorption and mimetics films before and after application by XRF showed that there was no damage to the mimetic. The cellulose/SBA-15 film as adsorbent in the acrylic resin in polychrome surface cleaning artwork by means of a solvent, is effective. This method is alternative and not intended to replace any existing one. Since, in restoration of works of art each case is specific and nothing replaces the knowledge, insight and conservator dexterity.
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