1000 resultados para resíduos industriais
Resumo:
Given that innovation is fundamental for competitiveness, and that it is intrinsically linked to knowledge, it has become essential to foster effective interaction between the Brazilian productive sector and universities and R&D centers. This interface should be created by means of the model used in developed countries: Observatory of Industrial Activities and Trends in Science, Technology and Innovation. The present work describes its main functions, using examples of activities undertaken by the Chemical Industry Information System of the Federal University of Rio de Janeiro related to production systems of primary and high-tech industries, examining the diffusion of knowledge to decision-makers.
Resumo:
Biocatalysts have innumerous advantages with respect to classical chemical processes, such as high specificity. Lipases (EC 3.1.1.3) are biocatalysts with large application in synthesis and hydrolysis reactions of triacylglycerols. The search for new sources of lipases has been intensified in the last years due to the high cost of microbial and animal lipases, wich restricts their use on an industrial scale. Lipases obtained from the latex of Carica papaya, Carica pentagona, Euphorbia characias, E. wulfenii, known for their proteolytic properties, are a good alternative source. In this review, we describe the well-known sources of vegetal lipases extracted from the latex and present some of their industrial applications.
Resumo:
Beginning students in chemistry usually do not realize that wastes generated in their experimental classes constitute an environmental problem and that residues must be treated or disposed of in a suitable way. In this manuscript we describe the work that we have been doing in the inorganic chemistry course of the Federal University of Rio Grande do Sul with the objective of creating a critical consciousness in the students about the chemical wastes they generate. With this policy, students are required to take into account the nature of the residues they generate, how they can treat or segregate them, and how they can keep them in a suitable way for final destination, instead of simply throwing them away.
Resumo:
The University of Brasília (UnB) uses a diversity of chemical products, generating residues in a significant way in its multiple activities - teaching, research and community services. The UnB Comission on Chemical Residues Management was established in November 2002, aiming at three main objectives: 1) correct destination for the accumulated residues; 2) implantation of a chemical residues management system and 3) implantation of a UnB Unit for Treatment of Chemical Residues. To fulfil these commitments, a diagnosis of chemical residues produced by the University was performed, which is here presented with an evaluation of their future use, limitations and possibilities.
Resumo:
Organic residue analysis of archaeological potsherds is a well-established method for determining the uses of European and North American pottery vessels. In the present work we assess if the organic residues identified in Brazilian potsherd extracts are related to commodity processes (e.g. cooking or surface treatment) or to other non-archaeological sources, using as a model potsherds recovered from the Rio do Meio site (Santa Catarina Island). The potsherd extracts are dominated by saturated fatty acids (Ac16:0, with lower abundances of Ac14:0 and Ac18:0). Our studies provide evidence that the organic residues preserved in the Brazilian archeological potsherds are related to foodstuffs and surface treatment processes of the pottery vessels.
Resumo:
The present work shows a method for the determination of chloramphenicol (CAP) antibiotic in milk, powder milk and honey. The solid phase extraction and liquid-liquid extraction were applied as a clean-up and pre-concentration strategies followed by LC-ESI/MS/MS analysis. The recovery was studied for different fortification levels from 0.05 to 1.00 µg L-1 in milk, showing values between 91 101% and RSD bellow 8.0%, while honey was spiked with a concentration of 0.20 µg kg-1 yelding a mean recovery of 83% and RSD of 6.5%. The quantification transition 321>152 showed a LOD of 0.52 ng kg-1 and LOQ of 1.85 ng kg-1.
Resumo:
The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.
Resumo:
A micellar electrokinetic chromatographic method (MEKC) is described for determining residues of amphenicols(chloramphenicol,thiamphenicol and florfenicol) in bovine milk. MEKC is conducted by using a separation buffer consisting of 20 mM Na2HPO4, 10 mM Na2B4O7, 50 mM SDS at pH 8.0; UV detection at 210 nm and 10 kV of voltage. The limit of detection ranged from 4.3-5.3 µg L-1. The MEKC method was applied for the simultaneous determination of amphenicols in milk samples spiked with amphenicols at three concentration levels: 10, 30 and 50 µg L-1. Recoveries ranging from 91-105% were obtained by following a simple extraction/preconcentration procedure.
Resumo:
Experimental procedures based on factorial design and surface response methodology were applied to establishe experimental conditions for the decomposition of a 1:400 (v/v) Supocade® (chlorfenvinphos 13.8% and cypermethrin 2.6%) solution, used to control cattle ticks. Experiments exploring photo-oxidative reactions were performed with and without UV radiation, fixing exposition time and pesticide volume, and varying the oxidant mixture. The use of 3.6 mmol L-1 Fe2+ plus 1.9 mol L-1 H2O2 plus UV radiation provided destruction of 94% of the original carbon content and reduction of aromatic, aliphatic and carbinolic compounds, evaluated by determination of residual carbon content by ICP OES and NMR analysis.
Resumo:
Pectic substances are structural heteropolysaccharides that occur in the middle lamellae and primary cell walls of higher plants. They are composed of partially methyl-esterified galacturonic acid residues linked by alpha-1, 4-glycosidic bonds. Pectinolytic enzymes are complex enzymes that degrade pectic polymers and there are several classes of enzymes, which include pectin esterases, pectin and pectate lyases and polygalacturonases. Plants, filamentous fungi, bacteria and yeasts are able to produce pectinases. In the industrial world, pectinases are used in fruit juice clarification, in the production of wine, in the extraction of olive oil, fiber degumming and fermentation of tea, coffee and cocoa.
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Cleaning solutions containing EDTA are widely employed to remove incrustation despite of the costs involved. The free content of EDTA in commercial solutions may be determined by mixing an aliquot to ammonium oxalate and using a standard calcium solution as titrant. The end-point is detected by the formation of insoluble calcium oxalate after all EDTA is complexed. A system for turbidimetric detection of the end-point was envisaged to substitute the visual detection, which impaired the analyses of dark samples. The proposed method was tested with real samples and good accuracy and precision was obtained.
Resumo:
The plating process generates solid waste rich in heavy metals and aiming to reduce environmental impact of such waste, this work suggests a methodology for zinc reduction, through a 2(4) factorial planning, studying the influence of the following variables: acid concentration (15, 20 or 30% v/v), acid type (sulfuric or hydrochloric), acid volume (15, 20 or 25 mL) and extraction time (12, 24 or 36 h). Through this methodology it is possible to establish the optimal conditions (15 mL of a 30% hydrochloric acid concentration during 12 h) to get a 100% efficiency in zinc extraction.
Resumo:
In an effort to minimize the impact on the environment, removal of pollutants, such as phenolic compounds, from the industrial wastewater has great importance nowadays because of the high toxicity and low biodegradability of these compounds. This work discusses the different methods to remove these compounds from industrial wastewater, showing their advantages and disadvantages. Advanced Oxidation Process (AOPs) are presented as a promising technology for the treatment of wastewater containing phenolic compounds. Among the AOPs, photolysis, photocatalysis and the processes based on hydrogen peroxide and on ozone are discussed with emphasis on the combined processes and the oxidation mechanisms.
Resumo:
The influence of nitric-perchloric, aqua regia, dry ashing and microwave digestion methods, in combination with 100 and 200 mg of sample, on the characterization and recovery of nutrients in samples of sludge sewage, poultry, swine, quail and bovine manures, organic compost, organic substrate and humic material were studied. Nitric-perchloric digestion with 200 mg samples recovered the higher nutrient contents. The nitric-perchloric method recovered also low levels of K. Dry ashing caused S volatilization and microwave digestion produced dark color extracts and this impaired S determination. Aqua regia recovered the lowest contents of nutrients in the organic residues evaluated.
Resumo:
The importance of urban solid waste integrated systems is characterized by the several components of these systems, which are, basically, formed by physical, chemical and biological methods. This article, characterizes these methods and, which is also important, identifies the several and potential environmental impacts of those techniques. It's also extremely important to make a study of the economic rentability of those infrastructures and, also, characterize the quantitative energetic contributions of some components of these systems. This study was analysed and their results are presented in this article.