Made available in DSpace on 2014-12-17T15:42:15Z (GMT). No. of bitstreams: 1 LoildeDB_TESE.pdf: 2292456 bytes, checksum: 7268473c8f078f403990f633d690589e (MD5) Previous issue date: 2012-10-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The contamination by metal ions has been occurring for decades through the introduction of liquid effluent not treated, mainly from industrial activities, rivers and lakes, affecting water quality. For that the effluent can be disposed in water bodies, environmental standards require that they be adequately addressed, so that the concentration of metals does not exceed the limits of standard conditions of release in the receptor. Several methods for wastewater treatment have been reported in the literature, but many of them are high cost and low efficiency. The adsorption process has been used as effective for removal of metal ions. This paper presents studies to evaluate the potential of perlite as an adsorbent for removing metals in model solution. Perlite, in its natural form (NP) and expanded (EP), was characterized by X-ray fluorescence, X-ray diffraction, surface area analysis using nitrogen adsorption (BET method), scanning electron microscopy and Fourier transform infrared spectroscopy. The physical characteristic and chemical composition of the material presented were appropriate for the study of adsorption. Adsorption experiments by the method of finite bath for model solutions of metal ions Cr3+, Cu2+, Mn2+ and Ni2+ were carried out in order to study the effect of pH, mass of the adsorbent and the contact time on removal of ions in solution. The results showed that perlite has good adsorption capacity. The NP has higher adsorption capacity (mg g-1) than the EP. According to the values of the constant of Langmuir qm (mg g-1), the maximum capacity of the monolayer was obtained and in terms of proportion of mass, we found the following order experimental adsorption: Cr3+ (2.194 mg g- 1) > Ni2+ (0.585 mg g-1) > Mn2+ (0.515 mg g-1) > Cu2+ (0.513 mg g-1) and Cr3+ (1.934 mg g-1)> Ni2+ (0.514 mg g-1) > Cu2+ (0.421 mg g-1) > Mn2+ (0.364 mg g-1) on the NP and EP, respectively. The experimental data were best fitted the Langmuir model compared to Freundlich for Cu2+, Mn2+ and Ni2+. However, for the Cr3+, both models fit the experimental data / A contamina??o por ?ons met?licos vem ocorrendo h? d?cadas atrav?s do lan?amento de efluentes l?quidos n?o tratados, principalmente de atividades industriais, nos rios e lagos, comprometendo a qualidade da ?gua. Para que os efluentes possam ser descartados em corpos d'?gua, as normas ambientais exigem que os mesmos sejam adequadamente tratados, de modo que a concentra??o dos metais n?o ultrapasse os limites de condi??es padr?es de lan?amento no corpo receptor. V?rios m?todos para tratamento de efluentes t?m sido apresentados na literatura, por?m muitos deles s?o de alto custo e baixa efici?ncia. O processo de adsor??o vem sendo utilizado como eficaz para remo??o de ?ons met?licos. Neste trabalho s?o apresentados estudos para avaliar a potencialidade da perlita como adsorvente na remo??o de metais em solu??o modelo. A perlita, na sua forma natural (PN) e expandida (PE), foi caracterizada por fluoresc?ncia de raios X, difra??o de raios X, an?lise da ?rea superficial usando adsor??o f?sica de nitrog?nio (m?todo BET), microscopia eletr?nica de varredura (MEV) e espectroscopia de infravermelho com transformada de Fourier (FTIR). As caracter?sticas f?sicas e a composi??o qu?mica apresentadas pelo material foram adequadas para o estudo de adsor??o. Ensaios de adsor??o pelo m?todo de banho finito para solu??es modelo dos ?ons met?licos Cr3+, Cu2+, Mn2+ e Ni2+ foram realizados, com intuito de estudar o efeito do pH, da massa do adsorvente e do tempo de contato na remo??o de ?ons em solu??o. Os resultados demonstraram que a perlita apresenta boa capacidade de adsor??o. A PN apresenta maior capacidade de adsor??o (mg g-1) do que a PE. De acordo com os valores da constante de Langmuir, qm (mg g-1), a capacidade m?xima da monocamada foi obtida e em termos de propor??o de massa, encontrou-se a seguinte ordem experimental de adsor??o: Cr3+ (2,384 mg g-1) > Ni2+ (0,585 mg g-1) > Mn2+ (0,515 mg g-1) > Cu2+ (0,513 mg g-1) sobre a PN e Cr3+ (1,932 mg g-1) > Ni2+ (0,514 mg g-1) > Cu2+ (0,421 mg g-1) > Mn2+ (0,364 mg g-1) sobre a PE. Os dados experimentais se ajustaram melhor ao modelo de Langmuir em rela??o ao de Freundlich para os ?ons Cu2+, Mn2+ e Ni2+. No entanto, para os ?ons Cr3+, ambos, os modelos se ajustaram adequadamente aos dados experimentais

During production of steel, slag is formed as a by-product. The process of steelmaking involves usage of additives such as chromium or vanadium as reactants to optimize and produce high quality steel. Vast amounts of slag are formed and there is a continuous search for applications that can make good use of the slag. Currently the use of slag in cleaning of metal polluted waters is researched and promising results has been found for many different types of slags. In this work two different AOD-slags has been used as sorbents for some selected elements (Zn, V, Cr, Mo, Pb, Li, Cd, Ba, Cu, Ni). The main difference between the two slags is the reducing agent that has been used, aluminium and silicon. This results in slags with different adsorption properties. The aluminium reduced slag show tendency for better adsorption capacities in general for the tested elements (Zn, V, Cr, Mo, Pb, Li, Cd, Ba, Cu, Ni), with a few exceptions. The buffering capacity of the materials were high, shown by the fact that final pH reached nearly 11.5 independent of the start pH (varied between 2 and 8). The adsorption process was rather quick and 24 minutes contact time was in most cases sufficient to reach equilibrium. For several of the elements e.g. Lithium, the maximum capacity of the slags was not reached even though a load of 3,07 mg Lithium was added per gram of slag.

The distribution of heavy metals between soil and soil solutions is a key issue in evaluating the environmental impact of long term applications of heavy metals to land. Contamination of soils by heavy metals has been reported by many workers. Metal adsorption is affected by many factors, including soil pH, clay mineralogy, abundance of oxides and organic matter, soil composition and solution ionic strength. The pH is one of the many factors affecting mobility of heavy metals in soils and it is likely to be the most easily managed and the most significant. To provide the appropriate level of protection for aquatic life and other uses of the resource, it is important to be able to predict the environmental distribution of important metals on spatial and temporal scales and to do so with particular emphasis on the water column concentrations. Regulatory levels reflected in water quality criteria or standards are based on water column concentrations. Predicting water column concentrations requires a consideration of the interactions of water column contaminants with both bed sediments and suspended particulates as critical components in the assessment. The adsorption behaviour of cadmium, copper, lead and zinc onto soils is studied under the various geo-environmental conditions of pH, concentration of adsorbate and adsorbent, and solution compositions. Experiments were conducted to determine the equilibrium contact time of various adsorbates for adsorbent in different systems. Experiments were also conducted to check the efficiency of various acid-mixtures to extract heavy metal from soils into the aqueous phase. The adsorption behaviour of heavy metals onto soils was also studied from sea-water system. Soils are characterized in terms of the role of clay minerals to remove the metals from the solution phase, back-ground levels of metals, maximum adsorption capacity to adsorb various heavy metals from different adsorption systems, and type of surface sites present. The experimental data of metal adsorption is described by Langmuir adsorption model. The adsorption data are also expressed in terms of surface loading, surface acidity, adsorption density, and affinity of soils for heavy metals in different adsorption systems. Ecological implications of changes in physical and chemical conditions in aquatic systems on heavy metals uptake by soils are also discussed. This research covers the following areas: the environmental impact of heavy metal discharge into the aquatic systems, the study of the mobility patterns of different heavy metals as function of geo-environmental conditions, and determination of the pathways and the ultimate fate of heavy metals in the environment.

Presence of a chelating ligand in the clay structure significantly improves its ability to immobilize heavy metals from contaminated sludge or wastewater. Two-step modification procedure comprising sequential pillaring and grafting of chelating agent to the modified clay is involved. Montmorillonite and kaolin were chosen as typical examples of expandable and non-expandable clays, correspondingly. Modifications with silica and ferric oxide were targeted on development of mesoporous structure. Laboratory tests of the organoclay efficiency for purification of wastewater were conducted with the most promising sample, i.e. organoclay with the highest specific loading of chelating agent. Experiments were conducted with model wastewater containing either individual or mixed cations of heavy metals. The modified organoclay displayed a high adsorption capacity on heavy metal cations even in acidic media. The method of modification presented in this work can be used for synthesis of efficient adsorbents for applications in contaminated areas.

No description available.

A aplicação de microrganismos capazes de adsorver metais se destaca dentre as técnicas para biorremediação ambiental. O objetivo deste trabalho foi isolar e identificar bactérias com potencial de emprego nesta tecnologia. A partir de amostras de solo, água e sedimentos coletadas da mina Sossego da VALE em 4 eventos de coleta, foram isoladas 73 bactérias resistentes à altas concentrações de Cu2+. Para a identificação dos isolados utilizaram-se diversos métodos: MALDI-TOF; sequenciamento de parte dos genes 16S rRNA e rpoD; construção de árvores filogenéticas; e provas bioquímicas. Foram selecionadas 12 bactérias pertencentes a pelo menos, 8 espécies diferentes, sendo a maioria pertencente ao gênero Cupriavidus. 75% dos isolados apresentou resistência a Cu2+ superior a de C. metallidurans CH34, bactéria mais resistente a Cu2+ conhecida. Valores de adsorção de Cu2+ superiores aos desta bactéria também foram observados em 5 isolados. Os resultados obtidos indicam que os isolados selecionados apresentam alto potencial para aplicação em biorremediação ambiental. / The application of microorganisms capable of adsorbing toxic metals stands out from other bioremediation techniques. This study aimed to isolate and identify bacteria with potential for bioremediation of environments contaminated by copper ions. From soil, water and sediment samples collected at VALE`s Sossego mine collected at 4 different occasions, 73 copper resistant bacteria were isolated. For the identification of the isolates, various methods were used: MALDI-TOF, sequencing of part from the genes rRNA and rpoD; construction of phylogenetic trees; and biochemical tests. 12 bacteria that belong to at least 8 different species were selected. 75% of the isolates were resistant to Cu2+ exceeding C. metallidurans CH34, the, most resistant bacteria to Cu2+ known. The ion adsorption capacity of 5 isolates was greater than those for C. metallidurans. The results obtained for the bacterial isolates indicate that they have a high potential for application in environmental bioremediation.

A aplicação de microrganismos capazes de adsorver metais se destaca dentre as técnicas para biorremediação ambiental. O objetivo deste trabalho foi isolar e identificar bactérias com potencial de emprego nesta tecnologia. A partir de amostras de solo, água e sedimentos coletadas da mina Sossego da VALE em 4 eventos de coleta, foram isoladas 73 bactérias resistentes à altas concentrações de Cu2+. Para a identificação dos isolados utilizaram-se diversos métodos: MALDI-TOF; sequenciamento de parte dos genes 16S rRNA e rpoD; construção de árvores filogenéticas; e provas bioquímicas. Foram selecionadas 12 bactérias pertencentes a pelo menos, 8 espécies diferentes, sendo a maioria pertencente ao gênero Cupriavidus. 75% dos isolados apresentou resistência a Cu2+ superior a de C. metallidurans CH34, bactéria mais resistente a Cu2+ conhecida. Valores de adsorção de Cu2+ superiores aos desta bactéria também foram observados em 5 isolados. Os resultados obtidos indicam que os isolados selecionados apresentam alto potencial para aplicação em biorremediação ambiental. / The application of microorganisms capable of adsorbing toxic metals stands out from other bioremediation techniques. This study aimed to isolate and identify bacteria with potential for bioremediation of environments contaminated by copper ions. From soil, water and sediment samples collected at VALE`s Sossego mine collected at 4 different occasions, 73 copper resistant bacteria were isolated. For the identification of the isolates, various methods were used: MALDI-TOF, sequencing of part from the genes rRNA and rpoD; construction of phylogenetic trees; and biochemical tests. 12 bacteria that belong to at least 8 different species were selected. 75% of the isolates were resistant to Cu2+ exceeding C. metallidurans CH34, the, most resistant bacteria to Cu2+ known. The ion adsorption capacity of 5 isolates was greater than those for C. metallidurans. The results obtained for the bacterial isolates indicate that they have a high potential for application in environmental bioremediation.

No description available.

The goal of this study was to characterize the binding sites on the surface of wheat roots, Triticum turgidum, involved in the adsorption of protons and metals, and quantify the thermodynamic constants needed for a surface complexation model to predict metal binding. The adsorption of protons, Cd(II), Cu(II), and Ni(II) to the root surface as a function of pH and ionic strength in single metal exposure scenarios was quantitatively described using potentiometric titrations, batch metal adsorption experiments, and the least squares fitting program FITEQL. Model predictions from single metal exposures were compared to measured metal adsorption concentrations when roots were exposed to binary and ternary combinations of the metals. Proton dissociation was a function of three discrete monoprotic acid sites on the root surface with log proton dissociation constants of -4.50, -6.23, and -7.37 respectively, upon which varied ionic strength had no effect. The total proton binding capacities for the three sites were 2.58 x 10-4, 1.29 x 10-4, and 2.58 x 10-4 M, respectively. Metal complexation was best described by a two-site model having conditional stability constant log values of 3.04 and 3.30 for Cd(II), 3.21 and 3.25 for Cu(II), and 2.83 and 2.84 for Ni(II) at ionic strength 0.01M. At ionic strength 0.1 M the conditional stability constants log values were 2.37 and 3.36 for Cd(II), 3.11 and 2.56 for Cu(II), and 2.18 and 3.00 for Ni(II). When roots were exposed to binary or ternary mixtures of the metals, the two monoprotic acid single metal model did not provide ideal fits to the data indicating that adsorption in a metal mixture scenario cannot be considered additive and is dependent on the combination of metals present in the exposure environment. The experimentally determined proton dissociation constants and metal stability constants could be used in commercial geochemical speciation programs such as Visual MINTEQ to predict metal adsorption to plants. / Natural Sciences and Engineering Research Council of Canada, The Mining Association of Canada, Ontario Power Generation, Environment Canada.