Desenvolvimento de nanocompósito (hidroxiapatita/ poliuretano) pela gelação (gelling) de poli ( álcool vinílico) (PVA) para remoção de metais pesados

Removing microcontaminants from effluents is a challenge today, because of its high cost and low efficiency, especially in the treatment of effluents containing heavy metals. An alternative that has emerged is the use of biodegradable nanocomposites, which exhibit good removal and recovery performances, in addition to its low cost. With this in mind, the present study aimed to develop and characterize a nanocomposite based on hydroxyapatite (HAP), polyurethane (PU) and polyvinyl alcohol (PVA) for removing heavy metals. Thus, the research was conducted in several steps: i)- Physico-chemical and microbiological hospital effluent characterization; ii)- Production of hydroxyapatite by aqueous precipitation technique, and their characterization; iii)- Production of the nanocomposite in which the hydroxyapatite was added to the polyurethane prepolymers and then the polyvinyl alcohol/hydroxyapatite film was produced; iv)- Polyvinyl composite without film PU/HAp was also produced in the proportions of 20 and 40% HAp; v)- The composites was characterized by the techniques of XRD, FTIR, SEM / EDS, BET, Zeta Potential and TGA; vi)- The sisal and coconut fibres were washed and dried for comparative tests of adsorption; vii)- Adsorption tests for evaluating the removal of heavy metals (nickel and cadmium). Initial screening adsorption capacity (HAp; PU/HAp - 20 and 40%; PU / HAp / PVA), kinetic studies of adsorption of Cd (II) by HAp; multifactorial design analysis (factorial design) for identifying the most important variables in the adsorption of Cd (II) by composite PU/HAp. Also comparative analysis of adsorption of Cd and Ni by composite PU/HAp were conducted, as well as comparative tests of adsorption of Cd (coconut fibre) and Ni (sisal fibre). It was possible to verify that the composite PU/HAp 40% showed better effectiveness for the removal of Cd (II) and Ni (II), above 80%, equivalent to the lignocellulosic fibre used and HAp produced. As main conclusion, it can be referred that the composite PU/HAp 40% is an effective adsorvent to wastewater treatment for heavy metal removal, with low cost and high efficiency

Incorporação de cinzas da casca de café na produção de placas cerâmicas para revestimento

Brazil is the world s leading coffee producer. In 2008, 45.99 million of 60 kg bags of benefited coffee were produced. In the process of improvement 50% is grain and 50% is husk, thus, 1.38 million tons of coffee husk are produced annually. The husk is used as combustible in the drying and improvement ovens in the coffee farms, generating ash as residue. These ashes contain a high concentration of alkaline metals and earth metals, mainly K2O and CaO. This work studies the use of this residue in the ceramic tiles industry, as fluxing agents in substitution to the feldspar. Ten mixtures with equal ratios of clay and kaolin, proceeding from Bahia and the residue (varying from 30 to 5%) were defined and produced in uniaxial tool die of 60x20mm with approximately 5 mm of thickness and 45MPa compacting pressure. The samples were fired in four different temperatures: 1100 °C, 1150 °C, 1185 °C and 1200 °C during 60 minutes and characterized by means of X-ray fluorescence, X-ray diffraction, gravimetric thermal analysis and differential thermal analysis. The results of water absorption, apparent porosity, linear shrinkage, XRD, dilatometry, flexural strength and SEM were also analysed. The test specimen with addition of 10% of ash fired in 1200 °C resulted in 0.18% water absorption and 40.77 MPa flexural strength, being classified as porcelain stoneware tiles according to ABNT, UNI and ISO norms

Estudo do aproveitamento do rejeito da mineração de esmeraldas na produção de refratários conformados isolantes

Emerald mining is an important area of the economy in Brazil, country which is in second place among the exporting nations of this gem. Due to the process of extraction, a great amount of reject is generated. Since there is no appropriate destination, the reject is abandoned around the mining industries, contributing to environment degradation. Nowadays, some of the most relevant things to an industry in general are: energy conservation, cost reduction, quality and productivity enhancement. The production of isolating, transformed refractory materials achieves the sustainability dimension when protection of the environment is incorporated to such process. This work investigates the use of emerald mining rejects in the ceramic body of refractory materials, aiming at obtaining a product whose characteristics are compatible with commercial products and, at the same time, allow the use of such rejects to solve the environmental issue caused by its disposal in nature. X-ray fluorescence analysis show that the emerald reject obtained after the flotation to extract molybdenum and mica has 70% of silica and alumina (SiO2+Al2O3) and 21% of a basic oxides and alkaline metals and earthy alkaline mixture (Na2O, K2O, CaO e MgO). Because of the significant amount of silica and alumina present in the reject, four refractory ceramic bodies were prepared. Samples with a rectangular shape and dimensions 100x50x10 mm were pressed in a steel mold at 27,5 MPa and sintered at 1200ºC for 40 min. under environment atmosphere in a resistive oven. The sintered samples were characterized in relation to the chemical composition (FRX), mineralogical composition (DRX), microstructure (MEV) and physical and mechanical properties. The results indicate that the mixture with 45% of reject, 45% of alumina and 10% of kaolin presents a refractory quality of 1420ºC, dimensional linear variation below 2.00%, apparent specific mass of 1,56 g/cm3 and porosity of 46,68%, which demonstrates the potential use of the reject as raw material for the industry of isolating transformed refractory materials

Teores de metais na biomassa de Egeria densa, Egeria najas e Ceratophyllum demersum

Este estudo foi realizado com o objetivo de se estimar o conteúdo de elementos metálicos presentes em três macrófitas aquáticas submersas, procurando avaliar a participação destas plantas na remoção destes elementos na água e criar base de dados que permita prever o impacto ambiental do descarte delas em solo ou na própria água. As amostras foram desidratadas, moídas e encaminhadas aos laboratórios para análise e quantificação dos elementos. Para as três espécies, a maior concentração de elementos foi observada durante o verão, ocorrendo declínio nas concentrações durante o inverno, principalmente para os elementos vanádio e chumbo. Não foi detectada presença do elemento mercúrio em nenhuma das amostras.

Remoção conjugada de metais e óleo de água produzida

Petroleum can be associated or not with natural gas, but in both cases water is always present in its formation. The presence of water causes several problems, such as the difficulty of removing the petroleum from the reservoir rock and the formation of waterin-oil and oil-in-water emulsions. The produced water causes environmental problems, which should be solved to reduce the effect of petroleum industry in the environment. The main objective of this work is to remove simultaneously from the produced water the dispersed petroleum and dissolved metals. The process is made possible through the use of anionic surfactants that with its hydrophilic heads interacts with ionized metals and with its lipophilic tails interacts with the oil. The studied metals were: calcium, magnesium, barium, and cadmium. The surfactants used in this research were derived from: soy oil, sunflower oil, coconut oil, and a soap obtained from a mixture of 5wt.% coconut oil and 95wt.% animal fat. It was used a sample of produced water from Terminal de São Sebastião, São Paulo. As the concentration of the studied metals in produced water presented values close to 300 mg/L, it was decided to use this concentration as reference for the development of this research. Molecular absorption and atomic absorption spectroscopy were used to determine petroleum and metals concentrations in the water sample, respectively. A constant pressure filtration system was used to promote the separation of solid and liquid phases. To represent the behavior of the studied systems it was developed an equilibrium model and a mathematical one. The obtained results showed that all used surfactants presented similar behavior with relation to metals extraction, being selected the surfactant derived from soy oil for this purpose. The values of the partition coefficients between the solid and liquid phases " D " for the studied metals varied from 0.2 to 1.1, while the coefficients for equilibrium model " K " varied from 0.0002 and 0.0009. The removal percentile for oil with all metals associated was near 100%, showing the efficiency of the process

Disponibilidade de metais pesados em Latossolo com aplicação superficial de escória, lama cal, lodos de esgoto e calcário

O objetivo deste trabalho foi avaliar alguns atributos químicos do solo e a disponibilidade de cádmio (Cd), cromo (Cr), níquel (Ni), mercúrio (Hg), chumbo (Pb) e arsênio (As), por meio da extração pelo DTPA, em conseqüência da aplicação superficial de escória de aciaria, lama cal e lodos de esgoto centrifugados e de biodigestores, nas doses 0 (testemunha), 2, 4 e 8 Mg ha-1 e um tratamento adicional composto pela calagem superficial na dose 2 Mg ha-1. O experimento foi conduzido em delineamento de blocos ao acaso, em condições de campo, em área sob sistema plantio direto, durante 2003 e 2004. A aplicação superficial de escória de aciaria, lama cal, lodo de esgoto centrifugado e de biodigestor, até a dose 8 Mg ha-1, assim como o calcário na dose 2 Mg ha-1, não trazem problemas de disponibilidade ao ambiente, com relação aos metais pesados Cd, Cr, Hg, Pb, Ni e As, quando aplicados sobre a superfície em Latossolo Vermelho distrófico, no sistema plantio direto. A fitodisponibilidade de metais pesados às culturas da soja e aveia-preta foi nula, quando foram aplicadas doses de até 8 Mg ha-1 de lodo de esgoto, escória e lama cal sobre a superfície do solo, no sistema plantio direto.

Extração de metais pesados de efluentes da indústria do petróleo utilizando derivados de óleos vegetais como extratantes

The study of a promising alternative for the treatment of produced water from the oil industry envisaging its reuse was the focus of this work. Millions of liters of water are generated per day, containing heavy metals in low concentrations (< 0,15 mg/L for Pb, <0,04 mg/L for Cd, <0,04 mg/L for Ni). The technology applied to extract these metals from aqueous phase was the solvent extraction and the extratants used were vegetable oils originated from coconut oil. They can be used in natural form or as derivatives, known as MAC - Mixture of Carboxílics Acids. The determination of the heavy metal con¬centrations in a complex matrix was made by using the atomic absorption spectrometry technique (AAS). On the bench tests using synthetics aqueous solutions containing metals, vegetable oils showed no power to extract the metals studied. The extractant MAC was selective for the Pb> Cd> Ni, in the concentration of 8% in the same organic phase. In this condition, the lower efficiency of extraction obtained was 92% for the Pb, 69% for the Cd, in the range of pH ranging from 6 to 8. An experimental planning was conducted for continuous tests. The device used was called MDIF Misturador-Decantador à Inversão de Fases and the aqueous phase was produced water from Pólo Indutrial de Guamaré/RN . No correlation between the studied variables (concentration of metal, concentration of extratant and agitation in the mixing chamer) could be obtained, because of possible factors which occurred as: variation in the composition of the studied sample, phenomena of precipitation and complexation of metals in the reservoir of feed, solubility of extratant

Metais pesados do solo após aplicação de biossólido: I - Fracionamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Metais pesados do solo após aplicação de biossólido: II - Disponibilidade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uso e ocupação do solo e a concentração de metais pesados no sedimento e na água: bacia do rio Pitimbu

The accelerated growth of urban regions have produced relevant effects on water resources. Urban regions need an adequate institutional structure that can be able to face environmental demands and the adverse effects of land use on water resources. This study aims at analysing land use effects on heavy metals concentration in sediments and water, as well as making a comparative analysis involving water physical-chemical parameters. Applied methodology included both in loco water parameters measurement and water and bed sediment sampling at 8 sections along the fluvial system. Sample analysis was performed in laboratory in order to measure heavy metal concentrations. It was measured metal concentrations of Al, Cu, Pb, Cd, Fe, Ni and Zn. Once the samples were subjected to acid digestion (method 3050B), concentration values were measured by using atomic absorption spectrometry by flame (ICP-FLAA). The analysis results were compared with normative reference, these standards is intended to assess the risks of toxic substances in sediment and water management programs. The normative reference used in this work were: a) Ontario Ministry of the Environment and Energy (OMEE, 1993) b) Normative Netherlands (VROM, 2000); c) Normative Canadian (CCME, 1999); d) United States Environmental Protection Agency (USEPA, 1977), e) CONAMA Resolution No. 344/2004; f) CONAMA Resolution No. 357/2005. The high concentrations of iron (38,750 mg.g-1), Lead (1100 mg.g-1), Nickel (100 μg.g-1) and zinc (180 μg.g-1) detected sediments confirm the state of degradation of the aquatic system. Iron concentrations (1.08 mg.L-1), Aluminum (0.6 mg.L-1) and phosphorus (0.05 mg.L-1) present in the water are outside the established standards for human consumption

Preparação de vidros e vitrocerâmicas de óxidos de metais pesados contendo prata: propriedades ópticas, estruturais e eletroquímicas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da complexação de metais aos antiinflamatórios na ação contra agentes oxidativos e radicais livres: ação do cetoprofeno

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Hidróxido de níquel suportado em carbono: um catalisador de baixo custo para a eletro-oxidação de alcoóis em meio alcalino

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da influência da matéria orgânica, na determinação quantitativa de metais em amostras de sedimento, por espectrometria de absorção atômica e análise de metais traços por fluorescência de raios-X

The proposal of this work is to evaluate the influence of the organic matter on the results of the analyses of the metals (Zn, Pb, Al, Cu, Cr, Fe, Cd e Ni) for Atomic Absorption Spectrometry (AAS), so much in the extraction stage as in the reading using for that the chemometrics. They were used for this study sample of bottom sediment collected in river Jundiaí in the vicinity of the city of Macaíba-RN, commercial humus and water of the station of treatment of sewer of UFRN. Through the analyses accomplished by EAA it was verified that the interference of the organic matter happens in the extraction stage and not in the reading. With relationship to the technique of X Ray Fluorescence Spectrometry (XRFS), the present work has as intended to evaluate the viability of this technique for quantitative analysis of trace metals (Cr, Ni, Cu, Zn, Rb, Sr and Pb) in having leached obtained starting from the extraction with acqua regia for an aqueous solution. The used samples constitute the fine fraction (<0.063 mm) of sediments of swamp of the river Jundiaí. The preparation of tablets pressed starting from the dry residue of those leached it allowed your analysis in the solid form. This preliminary study shows that, in the case of the digestion chemistry partially of the fine fractions of bottom sediments used for environmental studies, the technique of applied EFRX to the analysis of dry residues starting from having leached with acqua regia, compared her it analyzes of the leached with ICP-OES, it presents relative mistakes for Cu, Pb, Sr and Zn below 10%

Estudo de titanatos nanoestruturados obtidos por tratamento hidrotérmico de óxido de titânio em meio alcalino

TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800ºC), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2−xTi3O7·nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200ºC, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2−xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400ºC. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150ºC, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase