Increasing public awareness of toxic moieties in our environment has put pressure on regulatory agencies to improve testing methods so that these harmful agents can be identified and quantitated at lower and lower levels. The main objective of this work was to investigate analytical methodologies that would allow the sensitive, selective determination of pollutants to be routinely possible. Polar, thermally labile sulfur-containing pesticides and pollutants were our focus analytes. This objective was achieved in two ways: 1) the development of supercritical fluid extraction procedures suitable for these compounds and 2) the interface of a sulfur-selective detector to chromatographic techniques appropriate for thermally labile compound analysis. Supercritical fluids, particularly CO₂, have recently been shown to be suitable replacements for traditionally used organic solvents in extraction. However, due to the polarity of the sulfonyl urea herbicides and thiocarbamate insecticides studied, pure CO₂ was found to be an ineffective extractant. Polar SF mixtures (2 and 5 % methanol-modified CO₂) were investigated as alternative supercritical extraction fluids. Of the modified fluids, only 2% methanol-modified fluid could be used due to post-SFE trapping problems encountered with the 5% modified fluid. The quantitative extraction of two of these herbicides from water at the 50 ppb level was achieved using the former SF. This SF was also used to extract three thiocarbamates from apples at the 2 ppm level. In order to achieve the second objective, a sulfur-selective gas chromatographic detector, the ozone-based sulfur chemiluminescence detector (SCD), was successfully interfaced to both packed column supercritical fluid chromatography (SFC) and microcolumn high performance liquid chromatography (micro-HPLC). The packed column SFC/SCD system was shown to be compatible with both pure CO₂ and methanolmodified CO₂ mobile phases with a detector sensitivity (2 pg S/sec.) comparable to that found with capillary SFC/SCD despite the presence of more CO₂, an effective chemiluminescence quenching agent. The equimolar response of this detector to sulfur was shown to be only somewhat affected by the coelution of other organic species and improper analyte combustion conditions. For micro-column HPLC/SCD, the detector was found to be compatible with methanol/water mobile phases. Mobile phase composition, mobile phase flow rate, air flow rate, and hydrogen flow rate were found to affect the detector's sensitivity. The detector's linear dynamic range, response factor, and detection limits were determined to vary as a function of mobile phase composition. Optimum sensitivity (600 fg S/sec.) was achieved with a mobile phase of 40% methano1l60% water mobile phase compositions investigated. The analysis of polyaromatic sulfur-containing hydrocarbons (PASH's), total sulfur in diesel fuel, and sulfonyl urea herbicides was realized with the SFC/SCD system while thiocarbamate pesticides from an apple matrix were examined with the HPLC/SCD system. / Ph. D.

A room temperature procedure for the partial extraction of heavy metals from soils was investigated in order to find an optimum combination of acid type, acid strength and digestion period. Hydrochloric and nitric acids were compared. The optimum set of variables would produce a maximum amount of adsorbed metal extraction, with a minimum amount of damage to the soil crystal structures, in the shortest possible time span. Samples were analyzed for aluminum, iron, lead, manganese and zinc. In addition, the amounts of metals extracted by the room temperature procedure were compared with the amounts of metals obtained from both a total extraction and a partial extraction procedure involving heat. The chosen optimum combination technique was performed on a known metals trend area. No clearly optimal combination of acid strength and digestion time was found which would be applicable to varying types of soils; statistical analysis yielded a compromise point of 1.4N hydrochloric acid and 10.5 hour digestion period, as the most suitable combination. This combination of variables proved suitable since predicted results were obtained from the known metals trend area. Nitric acid was eliminated due to the acid’s lower reactivity. Room temperature extractions using strong acids at extended contact times were found to attack silicate minerals, but solutions stronger than have previously been used may be utilized without damage to the soil structure. Extractions utilizing heat and concentrated acids were too destructive to be considered true partial extractions. / M.S.

For many years the problem of separating aliphatic and aromatic compounds has been at the forefront of the petroleum and oil refining industries. This separation is often effected using liquid-liquid extraction or extractive distillation. Both of these processes require the addition of a solvent to bring about separation. The aims of this work were to investigate the use of "mixed" solvents, such as those used in the Arosolvan process, for their application in liquid-liquid extraction and extractive distillation as well as to provide related thelmodynamic data for systems containing mixed solvents. In the last part of this work, a computer program was developed to theoretically predict the effectiveness of a number of solvents on a user-defined separation. The solvents used for liquid-liquid extraction were chosen based on their similarities to those in the Arosolvan process and were of the form, {N-methyl-2-pyrollidone (NMP) + glycerol, a glycol or water} where the glycol was either monoethylene glycol (MEG), diethylene glycol (DEG) or triethylene glycol (TEG). The additives were combined in various mixing ratios to NMP to determine a mixing ratio for which the effect of the solvent is possibly optimized (a list of all solvents and mixing ratios used are presented in this work). Solvent selectivity and the range of compositions over which separation could occur determined the effectiveness of the solvents. This work dealt with the separation of n-hexane and toluene. In order to determine the selectivity and range of compositions, the liquid-liquid equilibria (LLE) of systems containing n-hexane + toluene + solvent had to be determined. LLE was measured using a simple equilibrium cell at 298 K and 1 atm. The phase separation boundaries (binodal curves) were determined using a titration method. The results obtained in this work showed an increase in the range of compositions over which the mixture of n-hexane and toluene could be separated (i.e a larger range of mixing ratios over which these components could be separated from each other) from the pure NMP solvent to the mixed solvent cases. This implies that there is a The range of compositions over which separation could be affected is given (for the solvents) in descending order: NMP + 50% glycerol> NMP + 10% water > NMP + 30% MEG > NMP + 5% water > NMP + 30% glycerol> NMP + 10% glycerol > NMP + 10% MEG > NMP + 10% DEG > NMP + 10% TEG > NMP + 5% DEG > 100% NMP. The selectivities of the solvents showed a remarkable increase from the pure NMP case to the mixed solvent cases. The maximum selectivity obtained for the NMP + 10% DEG system was over 1200 compared to a maximum selectivity of just 6 for the pure NMP system. The maximum selectivities obtained in descending order were as follows: NMP + 10% DEG > NMP + 10% TEG > NMP + 10% glycerol > NMP + 10% MEG > NMP + 30% MEG > NMP + 50% glycerol > NMP + 10% water > NMP + 5% water > NMP + 30% glycerol > NMP + 5% DEG > 100% NMP. The binodal curves were modelled using the Hlavaty, ,8-density and log-y functions. The maximum standard deviations obtained were 0.075, 0.078 and 0.05 for each of the functions respectively. The equilibrium data was modelled using the UNIQUAC and NRTL thermodynamic models and showed excellent agreement. This work showed better agreement to the NRTL functions due to the fact that the non-randomness parameter, a ij , may be chosen arbitrarily. The results obtained in this work indicate that the use of mixed solvents greatly increases the effectiveness ofNMP used for the separation of n-hexane and toluene. It is suggested that further studies be performed on a wider range of aliphatic and aromatic compounds in order to determine whether this is a generic behaviour or just true for n-hexane and toluene. The effectiveness of each solvent for extractive distillation was determined by its separation factor. In order to determine separation factors, the activity coefficients at infinite dilution (IDACs) had to be measured. This was done using a gas-liquid chromatography technique. The solvents employed in this study were NMP, Glycerol, MEG, TEG, NMP + 10% glycerol, NMP + 10% MEG, NMP + 10% DEG, NMP + 10% TEG. The solutes used were: pentane, heptane, hexane, toluene and benzene. The separation factors were determined for each alkane/aromatic pair per solvent. The pure solvent cases were then compared to the mixed solvent cases. The mixed solvents did not show results as promising for extractive distillation applications as they did for liquid-liquid extraction. TEG displayed the best selectivities for each of the alkane/aromatic separations except for the heptane/benzene pair, for which NMP + 10% glycerol proved to be the most effective solvent. When compared to the results obtained from the original UNIF AC model, the IDACs obtained in this work showed up to a 99% deviation. This is due to the fact that the model does not work well for all types of molecules and does not predict the equilibrium of "unlike" molecules adequately. It is suggested that other mixing ratios and different solvents be used to further investigate the effectiveness of mixed solvents for extractive distillation applications. It is further recommended that a computer aided data logging system be developed to determine residence times. This would not only provide more accurate results, but also provide a database for future reference. The computer program that was developed using the original UNIF AC method contains a database of 28 commonly used industrial solvents. This program enables the user to compare graphically the effectiveness of each of the solvents on the desired separation. Due to the limitations of the original UNIF AC method, the program does not work well for all types of molecules. However, the model can be changed without altering the prografnming structure to include a modified version of the UNIFAC model depending on the users needs. The program although written from an extractive distillation standpoint can be extended to include liquid-liquid equilibrium predictions. The main benefit of such a program is to eliminate time-consuming experimental work required to narrow down a long list of solvents required for a particular separation by theoretically predicting the best solvents for the job. The solvent database can also be expanded when new solvents become available or the user needs change / Thesis (M.Sc. Eng)-University of Natal, Durban, 2003.

Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 137-143).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do presente trabalho foi desenvolver um método para extração de ácido fítico de farelo de arroz desengordurado (FAD) empregando-se banho ultrassônico e sua subsequente purificação por meio de resina de troca aniônica, e avaliar os efeitos inibitórios do padrão de ácido fítico (fitato de dodecassódio de arroz) sobre o desenvolvimento de esporos e o crescimento de células vegetativas de C. perfringens tipo A. A extração empregando-se banho ultrassônico foi realizada por meio de um planejamento fatorial 2³ com quintuplicata no ponto central e como variáveis independentes o pH de extração, a potência do ultrassom e o tempo de extração (minutos). Por meio dos resultados obtidos constatou-se que a quantidade de ácido fítico extraído aplicando-se a frequência de 80 kHz foi superior à extraída a 37 kHz (p ≤ 0,05). Pelo planejamento fatorial foi possível verificar que somente a variável pH apresentou efeito significativo (p ≤ 0,05) sobre a resposta. Nos experimentos de purificação, pela adsorção conduzida em batelada constatou-se que a resina Purolite A111 apresentou uma capacidade de adsorção satisfatória em relação às demais e seus dados de adsorção no equilíbrio obtidos experimentalmente foram melhor ajustados pelo modelo isotérmico de Langmuir (R² = 0,9650%). Os resultados obtidos a partir dos testes preliminares de dessorção demostraram que somente a solução dessorvente de NaCl 1,0 mol L¹ foi capaz de dessorver o ácido fítico da resina A111, sendo, portanto, a solução empregada para a realização dos experimentos de dessorção em batelada, cujos resultados foram interpretados e melhor ajustados pelo modelo isotérmico de Langmuir (R² = 0,9920). Os resultados de adsorção obtidos experimentalmente em coluna de leito fixo foram satisfatoriamente ajustados pelo modelo empírico de YoonNelson (R² = 0,9417). A resina A111 apresentou resultados satisfatórios nos experimentos de adsorção e dessorção em batelada e em coluna de leito fixo para a purificação de ácido fítico de FAD. Após os experimentos de purificação seguiu-se à realização dos experimentos de avaliação dos efeitos inibitórios do padrão de ácido fítico sobre o desenvolvimento de esporos e crescimento de células vegetativas de C. perfringens, por meio dos quais observou-se que nos meios de cultura suplementados com o padrão de ácido fítico houve inibição satisfatória do desenvolvimento dos esporos de C. perfringens por até 9,5 horas de incubação. Com relação às análises com as células vegetativas, nos meios contendo ácido fítico, houve inibição do crescimento das mesmas, sendo a concentração de AF de 1,0% efetiva na inibição por até 8 horas, apresentando efeito inibitório similar ao do sorbato de sódio (10%) (p ≥ 0,05). Finalmente, os resultados demonstraram o desenvolvimento de uma técnica nova e eficiente de extração e purificação de ácido fítico, proporcionando uma redução considerável do tempo de extração e um alto rendimento de ácido fítico extraído, o qual após purificado apresentou um alto grau de pureza (79,78%). Além disso, o padrão de ácido fítico foi eficaz como inibidor de esporos e células vegetativas de C. perfringens. / This study aims was to develop a method for extraction of defatted rice bran (DRB) phytic acid using ultrasonic bath and its subsequent purification by anion exchange resin, and evaluate the inhibitory effects of phytic acid standard (dodecasodium phytate from rice) on the C. perfringens type A spore outgrowth and growth of vegetative cells. A 23 factorial design with five central point was used to the ultrasonic bath extraction, and the independent variables were pH of extraction, ultrasound power, and the extraction time (minutes). The results showed that the amount of phytic acid extracted at a frequency of 80 kHz was higher than that extracted at 37 kHz (p ≤ 0,05). By the factorial design was verified that only the variable pH had a significant effect (p ≤ 0,05) on the extraction. In purification, by the batch adsorption experiments, was found that the Purolite A111 resin showed a satisfactory adsorption capacity compared to the other resins tested, and the batch adsorption data were better fitted by the Langmuir adsorption isotherm (R2 = 0,9650%). The results from preliminary desorption tests showed that only the solution of 1.0 mol L-1 NaCl was able to desorb phytic acid from A111 resin, and therefore, this solution was used in the batch desorption experiments. The batch desorption results were modelled and best fitted by the Langmuir isotherm model (R2 = 0,9920). The adsorption results of fixed bed column were satisfactorily fitted by the Yoon-Nelson empirical model (R2 = 0,9417). The A111 resin showed satisfactory results in adsorption and desorption by batch and fixed bed column experiments in the phytic acid purification. After purification experiments, the inhibitory effects of phytic acid pattern on the spores outgrowth and growth of vegetative cells of C. perfringens was evaluated. It was observed that the BHI medium supplemented with standard phytic acid has inhibited satisfactory the C. perfringens spores outgrowth at least for 9,5 hours of incubation. In the vegetative growth of C. perfringens in BHI medium supplemented with 1,0% standard phytic acid, there was growth inhibition, with an effective inhibition for at least 8 hours. This inhibitory effect was similar to the 10% sodium sorbate (p ≥ 0,05). Finally, the results showed the development of a new and efficient technique for phytic acid extraction and purification, providing a considerable reduction in the extraction time and a high yield of phytic acid extracted. This, after purified had a high purity (79,78%). Moreover, the standard phytic acid was effective as an inhibitor of spores and vegetative cells of C. perfringens

Orientador: Elias Basile Tamborgi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T23:13:38Z (GMT). No. of bitstreams: 1 Borracini_HeloisaMariaPitaro_M.pdf: 561004 bytes, checksum: e3b9d20443cd5c9315ba77c397ee51dc (MD5) Previous issue date: 2006 / Resumo: Bromelina é o nome dado a um conjunto de enzimas proteolíticas encontradas nos vegetais da família Bromeliaceae, da qual o abacaxi é o mais conhecido. A bromelina tem diversos usos, todos baseados em sua atividade proteolítica. Com a necessidade de desenvolver novos processos de purificação e concentração desses compostos, a extração líquido-líquido por rnicela reversa mostra-se como uma técnica atrativa, pois a micela reversa possui a capacidade de solubilizar biomoléculas específicas de uma solução aquosa, como o extrato bruto do abacaxi. O objetivo desse trabalho foi estudar a recuperação da enzima bromelina através da técnica de extração líquido-líquido por rnicelas reversas. Para tanto, utilizaram-se três sistemas micelares distintos formados a partir de BDBAC (agente tensoativo catiônico), AOT (agente tensoativo aniônico) e CTAB (agente tensoativo catiônico). Foram realizados planejamentos estatísticos com o intuito de realizar uma triagem das variáveis significativas em cada processo. A metodologia de superfície de resposta foi empregada para quantificação dos níveis das variáveis significativas à extração. No presente trabalho são apresentados estudos da influência conjunta que alguns parâmetros exercem sobre a extração líquido-líquido da bromelina com rnicelas reversas, nas etapas de extração e re-extração, para fins de caracterização, modelagem e otirnização / Abstract: Bromelain is a set of proteolitics enzymes found in vegetables of the Bromeliaceae family, from which pineapple is known more. Bromelain has several uses, alI based on its proteolitics activity. There are the necessity to develop new processes for purification and concentration of these composites, the liquid-liquid extraction by reversed micelles reveals as one attractive technique, therefore it has had the specific capacity of getting solub1e biomolecules of an aqueous solution, as the crude extract of the pineapple. This is a study on the recovery of bromelain through liquid-liquid extraction by reversed micelles. Three distinct micelar systems formed from BDBAC (cationic surfactant), AOT (anionic surfactant) and CTAB (cationic surfactant) were employed. Statistical designs were used to select the most significant variables for each process. Surface response methodology was used to quantify the levels of the significant variables. In this work systematic studies are performed on the influence that certain parameters have on the recovery of bromelain through liquid-liquid extraction by reversed micelles, concerning forward and back extration. The goal is the system mathematical characterization and otimization / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Made available in DSpace on 2016-08-19T12:56:44Z (GMT). No. of bitstreams: 1 Dissertacao Maria de Lourdes.pdf: 1957911 bytes, checksum: 71ed8d1c2f93361fcb544ae3efad37e2 (MD5) Previous issue date: 2013-01-25 / In the present study it was determined the total stock of phosphorus (PT) in sediments from Anil and Bacanga rivers located on Maranhão island. Additionally, with the aim of assessing the lability of phosphorus in the sediment, it was used sequential chemical extraction according to the protocol of the European Commission (Standards, Measurements and Testing Program). The results indicate PT concentrations ranging from 877.91 to 1466.44 mg. Kgˉ¹, which allows classifying these sediments moderate to highly polluted. The geochemistry of inorganic phosphorus fraction non apatite (PINA) was in mean 32% and the sum of organic fractions (PO) and PINA, considered the greatest lability, showed mean values of 65%, indicating that most of the phosphorus has potential to migrate to interstitial water. Principal component analysis indicates that the PO is proportional to organic matter (OM) and that the silt and clay did not showed good relationship with the fractions PIA and PINA in different sediments. Infrared absorption spectra reveal the intensification of bands in the region between 1200 and 1800 cmˉ¹, which features a large amount of minerals. Aiming to study the capacity of sediment P sorption was conducted adsorption experiments. Data were adjusted by Langmuir and Freundlich equation. For each batch experiment was calculated rate constant (k), the linear coefficient of determination (R²) and the maximum amount of P adsorbed (Qmax). The Langmuir model was suitable to describe the adsorption of P in sediments, because this model showed better linear coefficient of determination (R²). The sediments have yet expressive capacity of phosphate adsorption within the parameters of adsorption isotherms, which can act as a mitigating factor against the significant contribution of phosphorus via raw sewage. / No presente estudo, foi determinado o estoque total de fósforo (TP) em sedimentos de rios Anil e Bacanga localizados na ilha do Maranhão. Além disso, com a finalidade de avaliar a labilidade de fósforo no sedimento, foi realizada a extração química sequencial de acordo com o protocolo da Comissão Europeia (normas, medidas e programa de testes). Os resultados do Rio Bacanga indicou concentrações de PT que variam de 877,91 mg kgˉ¹ e 1466,44 mg Kgˉ¹, o que permite classificar estes sedimentos em moderado a altamente poluído. A geoquímica da fração de fósforo inorgânico não apatítico (PINA) foi em média, 32% e a soma do fósforo orgânico (PO) e PINA, considerado fração lábil, apresentaram valores médios de 65%, indicando que a maior parte do fósforo tem um potencial de migrar para a água intersticial. Análise de componentes principais indicou que o PO é proporcional ao teor de matéria orgânica (MO) e que o silte e argila não apresentou bom relacionamento com frações de fósforo inorgânico apatítico (PIA) e fósforo inorgânico não apatítico (PINA) nos sedimentos. Os espectros de absorção no infravermelho revelaram a intensificação das bandas na região entre 1200 e 1800 cmˉ¹, que apresenta uma grande quantidade de minerais. Com o objetivo de estudar a capacidade de sorção de P pelos sedimentos, foi realizado experimentos de adsorção. Os dados foram ajustados pela equação de Langmuir e Freundlich. Para cada experiência foi calculada a constante de velocidade (k), o coeficiente linear de determinação (R²) e a quantidade máxima de P adsorvido (Qmáx). O modelo de Langmuir foi o mais adequado para descrever a adsorção de P nos sedimentos. Os sedimentos têm capacidade mais expressiva de adsorção de fosfato dentro dos parâmetros de isotermas, que podem atuar como um fator de mitigação contra a contribuição significativa de fósforo através de esgoto.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2008. / The main goal of this study was the development of new technologies based on modern analytical techniques for analysis of volatiles in wines. Due to the exponential growth of the wine industry and consumer demands for an enjoyable, safe-to-consume, and high quality product, the need for arose for methodologies aiding the understanding of wine better arose. Chemical analysis is a valuable way of studying the composition of wine in depth. Very sophisticated instrumentation is available nowadays but almost always the sample needs to be cleaned up or concentrated before such analysis. This study investigates the use of stir bar sorptive extraction (SBSE) as such a technique. It is shown that SBSE combined with gas chromatography-mass spectrometry (GC-MS) is extremely suited for a wide number of analyses and during the course of the study the technique was applied for troublesome analytical challenges in various beverages and foodstuffs. The study focuses on the development of a screening technique for volatiles in wine using SBSE and the application of the data to various chemometrical techniques for classification purposes. A second part of the study shows the applicability of SBSE for extraction of pesticides, contaminants and preservatives from wine, water, lemon flavoured beverages and yoghurt. The method is also elaborated upon by development of faster analysis methods for wine and beer and the investigation of using SBSE for headspace sampling of wine. In all the applications, SBSE technology was shown to be sensitive, repeatable, robust and very simple to use.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2018-08-21T14:49:02Z No. of bitstreams: 1 2010 - Otavio Raymundo L?.pdf: 585290 bytes, checksum: ee9c2ebbd0832facdf245e177fef5fa4 (MD5) / Made available in DSpace on 2018-08-21T14:49:02Z (GMT). No. of bitstreams: 1 2010 - Otavio Raymundo L?.pdf: 585290 bytes, checksum: ee9c2ebbd0832facdf245e177fef5fa4 (MD5) Previous issue date: 2010-02-26 / Agricultural use of sewage sludge has become, increasingly, a practice adopted by sanitation companies to solve partly the problem of final disposal of waste. As the sludge to be used generally need to be dry and that the drying process can alter the distribution of metals, the general aim of this study was to evaluate the effect of drying temperature and storage time on chemical parameters and the metal availability and distribution. The specific objectives were: (i) to study how the drying temperature (air, 40?C and 65?C) sludge, associated with the storage time (zero-fresh, and one year), influenced the availability of metals and the possible chemical changes induced in the sludge, (ii) to evaluate how the high content of iron present and the microbial activity affect the availability of metals in the sludge studied, as a function of temperature of drying, and (iii) to characterize the soluble organic fraction leached by infrared absorption spectrometry in samples of dried sludge at different temperatures and stored for one year. Fresh and stored for one year sludge were dried with forced air circulation, grounded and chemical analyzed. The BCR sequential extraction was applied to assess the availability and distribution of metals. The drying of sewage sludge in the air encouraged increasing availability of metals, however, where temperature increased it diminished due to binding of metals with more stable compounds. The reduction of total organic carbon due to volatilization and biodegradation was favored by increased temperature. The decrease in the levels of iron and zinc, with increasing time and temperature drying to constant weight and pH close to neutral, favored readsorption and/or precipitation of metals to less labile forms. The wet sewage sludge, stored in refrigerated conditions (4?C), was subjected to different times and drying temperatures in the greenhouse and, after being re-moistened been and incubated (28 ? 1?C) for zero, one and three days. The methods of fumigation extraction and Mehlich3 were used to assess the microbial activity and availability of metals, respectively. Increased levels of soluble organic carbon and iron were directly related to the increase of incubation time and temperature drying. For leaching, the dried sludge?s were packed in PVC columns of 50 mm and related to the mass of wet sludge, on a dry basis. The increase in drying temperature of the sludge increased the organic carbon dissolved in the leachate extract, without, however, a corresponding increase in metal content in this extract. / A utiliza??o agr?cola de lodos de esgoto tem se tornado, cada vez mais, uma pr?tica adotada pelas companhias de saneamento, para resolver, em parte, o problema da disposi??o final do res?duo. Como o lodo para ser utilizado geralmente necessita estar seco, e que o processo de secagem pode alterar a distribui??o de metais, o objetivo geral deste trabalho foi avaliar o efeito da temperatura de secagem e do tempo de estocagem em par?metros qu?micos e na disponibilidade e distribui??o de metais. Os objetivos espec?ficos foram: (i) estudar em como a temperatura de secagem (ao ar, 40?C e 65?C) do lodo, associada ao tempo de estocagem (zero ? fresco, e um ano), influencia na disponibilidade de metais e quais as poss?veis altera??es qu?micas provocadas no lodo; (ii) avaliar em como os elevados teores de ferro presentes e a atividade microbiana afetam a disponibilidade de metais no lodo estudado em fun??o da varia??o da temperatura de secagem e (iii) caracterizar a fra??o org?nica sol?vel lixiviada por espectrometria de absor??o no infravermelho, nas amostras de lodo secas em diferentes temperaturas e estocadas por um ano. O lodo fresco e estocado por um ano, ap?s secagem em estufa com circula??o for?ada de ar, foi mo?do e submetido ?s an?lises qu?micas. Na avalia??o da disponibilidade e distribui??o de metais foi utilizado o m?todo de extra??o seq?encial do BCR. A secagem do lodo ao ar favoreceu o aumento da disponibilidade de metais, por?m, em temperaturas maiores esta diminuiu devido ? liga??o dos metais com compostos mais est?veis. A redu??o de carbono org?nico total devido ? volatiliza??o e biodegrada??o foi favorecida pelo aumento de temperatura. A diminui??o nos teores de ferro e zinco com o aumento do tempo e da temperatura de secagem a peso constante e o pH pr?ximo da neutralidade favorecem a readsor??o e/ou precipita??o de metais para formas menos l?beis. O lodo de esgoto ?mido, estocado em condi??es refrigeradas (4?C), foi submetido aos diferentes tempos e temperaturas de secagem na estufa e, ap?s ser re-umedecido e incubado (28 ? 1?C) por zero, um e tr?s dias. Para avalia??o da atividade microbiana e disponibilidade de metais foi utilizado o m?todo de fumiga??o extra??o e o extrator Mehlich 3, respectivamente. O aumento dos teores de carbono org?nico sol?vel e ferro foi diretamente relacionado ao aumento do tempo de incuba??o e temperatura de secagem. Para a lixivia??o, as amostras de lodos secas foram empacotadas em colunas de PVC de 50 mm e relacionados ? massa do lodo ?mido, em base seca. O aumento na temperatura de secagem do lodo causou o aumento no teor de carbono org?nico dissolvido no extrato lixiviado, n?o havendo, por?m, aumento correspondente no teor de metais nesse extrato.