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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

LIGNOCELLULOSIC ACTIVATED WASTE USE ADSORBENTS IN TOXIC METALS IONS REMOVAL: BATCH AND COLUMN STUDIES USING DESING EXPERIMENTAL / Uso de ResÃduos LignocelulÃsicos Ativados como Adsorventes na RemoÃÃo de Ãons MetÃlicos TÃxicos: Estudos de Batelada e Coluna Utilizando Planejamento Experimental.

Diego de Quadros Melo 27 November 2015 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / The tururi and buriti fibers, and the castor bean stalks are extremely efficient to sorption of metal ions from aqueous solutions. In this study, the adsorbents were activated with different concentrations of alkali solutions (5, 7, 10 and 15% w/v). The materials were characterized by analytical techniques as infrared, X-ray Diffraction (XRD) and Thermogravimetry analysis. The infrared spectra revealed that associated groups to macromolecules of hemicellulose and lignin after alkaline activation have less intensity compared to the initial samples. The XRD revealed, that after castor bean stalks alkaline activation, the presence of the cellulose type II peaks, which did not occur with tururi and buriti fibers. The fluorescence X-ray data showed that the cations present in the initial adsorbents, K+ and Ca2 + are exchanged by Cu (II), Ni (II), Cd (II) and Pb (II) in the sorption process. Studies of the influences of variables: mass of adsorbent; agitation rate; the initial pH and concentration using a fractional factorial design 24-1 demonstrated that all variables affect the response (adsorption capacity mg g-1). As a result for a larger value of qtotal, conditions were observed while maintaining the pH at 5.5; mass of the adsorbent 50 mg; agitation at 200 rpm and the initial concentration: 500 mg L-1. The adsorption kinetics revealed fast adsorption process, about 30 minutes, and good fitting to pseudo-second-order theoretical model to all adsorption process studied. Intraparticle diffusion models as Weber-Morris and Boyd were testes in order to study the limiting steps of the process.The results showed that for tururi and buriti fibers (with the exception of nickel ions) the rate-limiting step is not the intraparticle diffusion, while for the castor bean stalks, it was found that the rate-limiting step of the process is the intraparticle diffusion. The study of monoelement and multielement systems were performed at pH 5.5, initial concentrations from 20-500 mg L-1, which the experimental data were fitted to the Langmuir, Freundlich and Sips theoretical models. The tururi fibers adsorption capacities (mg g-1) in monoelementar and multielement system follows the order Pb (188.79)> Cd (92.20)> Cu (32.82)> Ni (22.23) and Cd (77.53)> Pb (43.93)> Cu (24.99)> Ni (19.51), respectively. Buriti fibers adsorption capacities (g-1 mg) in monoelementar and multielement systems follows the order of Cu (143.1)> Pb (112.1)> Ni (103.7)> Cd (86.33) and Pb (69.12)> Cu (49.28)> Ni (45.10)> Cd (24.95), respectively. Castor bean stalks adsorption capacities (g-1 mg) in in monoelementar and multielement systems follows the order of Pb (175.1)> Cd (124.8)> Ni (111.1)> Cu (89.23) and Cu (56.78)> Pb (55.82)> Cd (44.72)> Ni (43.48), respectively. The results showed a better fit for the Sips model, relating to a heterogeneous adsorption. Fixed bed studies using castor bean stalks checking the influence of variables adsorbent flow (1, 2 and 3 mL min-1), the height of the column (5, 7 and 10 cm) and initial concentration (100 , 200, 300 mg L-1) by the Box-Behnken planning revealed that there were no influence between the variables in the studied. The breakthrough curves were well fitted to the Thomas model. The study in real effluent with Cu (II) (galvanoplastic sector) was carried out using the optimized condition: flow (1 ml min-1); bed height (10 cm) initial concentration: (245.5 mg L-1) and it was found adsorption capacity of 32.42 mg g-1. The mamoneira stalks adsorbent was used for five cycles to verify their potential reuse, and it was found no significant efficiency losses. / As fibras tururi, buriti e talos da mamoneira sÃo resÃduos lignocelulÃsicos extremamente eficientes na sorÃÃo de metais de soluÃÃes aquosas. Neste trabalho, eles foram ativados com diferentes concentraÃÃes de soluÃÃes alcalinas (5, 7, 10 e 15% m/v). Os materiais foram caracterizados pelas tÃcnicas analÃticas de Infravermelho, DifraÃÃo de Raios-X (DRX) e Termogravimetria. Os espectros de infravermelho revelaram que os grupos associados Ãs macromolÃculas de hemicelulose e lignina diminuem em intensidade ou desaparecem apÃs a ativaÃÃo alcalina. Os DRX revelaram que apÃs a ativaÃÃo alcalina, os talos da mamoneira apresentaram picos de celulose tipo II, o que nÃo ocorreu com as fibras de tururi e buriti. O dados de FluorescÃncia de Raios-X revelaram que os cÃtions presentes nos adsorventes como Na(I) e Ca(II) sÃo trocados pelos Ãons Cu(II), Ni(II), Cd(II) e Pb(II) no processo de sorÃÃo. Os estudos das influÃncias das variÃveis: massa do adsorvente; taxa de agitaÃÃo; pH e concentraÃÃo inicial utilizando planejamento experimental fracionÃrio 24-1 demostrou que todas as variÃveis afetaram a resposta (capacidade de adsorÃÃo mg g-1). Como resultado para um maior valor de qtotal, as condiÃÃes observadas foram mantendo o pH em 5,5; massa do adsorvente em 50 mg; taxa de agitaÃÃo em 200 rpm e concentraÃÃo inicial 500 mg L-1. A cinÃtica de adsorÃÃo revelou rÃpida adsorÃÃo, cerca de 30 minutos em geral, seguindo o modelo de pseudo-segunda ordem em todos os processos adsortivos. Modelos de difusÃo intrapartÃcula como de Webber-Morris e Boyd foram estudados a fim de determinar as etapas limitantes do processo. Os dados evidenciaram que para as fibras de tururi e buriti (com exceÃÃo dos Ãons nÃquel) a etapa limitante da velocidade nÃo à a difusÃo intraporo, enquanto para os talos de mamoneira foi verificado que a etapa limitante do processo à a difusÃo intrapartÃcula. O estudo com sistema monoelementar e multielementar foi realizado em pH 5,5, concentraÃÃes variando de 20-500 mg L-1, nos quais os dados foram aplicados aos modelos de Langmuir, Freundlich e Sips. As capacidades de adsorÃÃo (mg g-1) em sistema monoelementar e multielementar das fibras de tururi segue a ordem Pb(188,79)> Cd(92,20)> Cu(32,82)> Ni(22,23) e Cd(77,53)> Pb(43,93)> Cu(24,99)> Ni(19,51), respectivamente. As capacidades de adsorÃÃo (mg g-1) das fibras de buriti em sistema monoelementar e multielementar segue a ordem Cu(143,1)> Pb(112,1)> Ni(103,7) > Cd(86,33) e Pb(69,12)> Cu(49,28)> Ni(45,10)> Cd(24,95), respectivamente. As capacidades de adsorÃÃo (mg g-1) dos talos de mamoneira em sistema monoelementar e multielementar segue a ordem Pb(175,1)> Cd(124,8)> Ni(111,1)> Cu(89,23) e Cu(56,78)> Pb(55,82)> Cd(44,72)> Ni(43,48), respectivamente. Em geral, os resultados evidenciaram melhor aplicabilidade ao modelo de Sips, o qual prediz que os sÃtios disponÃveis para adsorÃÃo sÃo heterogÃneos. Em relaÃÃo ao estudo de adsorÃÃo em leito fixo utilizando talos de mamoneira, a verificaÃÃo da influÃncia das variÃveis: fluxo do adsorvente (1, 2 e 3mL min-1), altura da coluna (5, 7 e 10 cm) e concentraÃÃo inicial (100, 200, 300 mg L-1) pelo planejamento de Box-Behnken, revelou que nÃo hà influencia mutua entre as variÃveis no intervalo estudado. As curvas de ruptura experimentais foram bem aplicadas ao modelo teÃrico de Thomas. O estudo com efluente real de Ãons Cu (II) (setor galvanoplÃstico) utilizando a condiÃÃo otimizada: fluxo (1mL min-1); altura de leito (10 cm) e concentraÃÃo inicial: (245,5 mg L-1) obteve 32,42 mg g-1 de capacidade de adsorÃÃo O adsorvente talos de mamoneira foi utilizado por cinco ciclos para verificar seu potencial de uso, nÃo havendo perdas significativas de eficiÃncia.
12

Možnosti využití slévárenských odprachů / The possibilities of using of foundry filter ash

Solik, Jaroslav January 2012 (has links)
This thesis explores the posibility of using of foundry filter ash for production of inorganic composite materials, that could be used primary in the construction industry. The thesis is divided into theoretical and experimental section, where theoretical section contain literature review of used materials and the experimental section summarizes the results of laboratory tests performed on tested mixture based on portland and alumina cement with various content of foundry filter ash. For comparison was also used another foundry waste - foundry sand. Prepared test bodies with dimension of 40 x 40x 160 mm was subjected to mechanical strength tests and the influence of amount of foundry waste on the strenght of the prepared mixtures was monitored. Next the thesis deals with possibilities of alkaline activation of foundry waste, where sodium water glass, sodium hydroxide and commercially supplied baucis L 160 component B were used as alkaline activator. These test mixtures were also subjected to mechanical strenght tests and the influence of amount of foundry waste on the strenght was observed too. The analysis of input materials were performed by XRF, TG – DTA – EGA and XRD powder diffraction methods. All strength tests were tested by testing equipment desttest 4310.
13

Mise en place d’une brique géopolymère pour la construction durable : études géotechnique, environnementale et économique / Geopolymer brick implementation for sustainable construction : geotechnical, environmental and economic studies

Youssef, Nicolas 14 June 2019 (has links)
Après la crise économique en 2008, l’activité de construction en France a connu une croissance très rapide. La hausse de la demande des matériaux de construction était accompagnée d’une augmentation des quantités de déchets de construction et de CO2 émise. En 2018, l’émission de CO2 liée aux activités humaines a atteint un niveau historique mondial de 37.1 milliards de tonnes. Ceci encourage le développement des matériaux de construction qui répondent aux besoins mutants de la société d’aujourd’hui et de demain. Les géopolymères, préparés par activation alcaline, présentent une opportunité pour produire des nouveaux matériaux plus performants et respectueux de l’environnement dans le secteur de la construction. D’autre part, l’industrialisation et la robotisation font apparition dans le secteur de la construction, avec des nombreux avantages tels que l’augmentation de la productivité, la réduction des gaspillages, du coût et de la pénibilité du travail, ainsi que l’amélioration de la qualité et la sécurité.Ce travail de recherche est mené pour répondre à ces défis et verrous scientifiques. Il est réparti selon trois axes : l’élaboration de nouvelles formulations de briques géopolymères, l’intégration des matériaux géopolymères dans le processus d’industrialisation et de robotisation de la construction, et enfin l’évaluation de l’impact environnemental et économique du nouveau système de fabrication automatisé. / After the economic crisis in 2008, construction activity in France grew rapidly. The increase in demand for building materials was accompanied by an increase in the quantities of construction waste and emitted CO2. In 2018, CO2 emissions from human activities reached a world historic level of 37.1 billion tons. This encourages the development of building materials that meet the changing needs of today's and tomorrow's society. Geopolymers, prepared by alkaline activation, present an opportunity to produce new, more efficient and environment-friendly materials in the construction sector. On the other hand, industrialization and robotization are emerging in the construction sector, with many benefits such as increased productivity, reduced waste, cost and arduous work, as well as improved quality and safety.This doctoral thesis is being conducted to address these scientific challenges and issues. These are divided into three research directions: the development of new geopolymer brick formulations, the integration of geopolymer materials into the industrialization and robotization of construction processes, and finally the environmental and economic assessment of the new automated manufacturing system.

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