997 resultados para Ensaios de caracterização
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Initially concentrated in some poles at the South and Southeast regions of Brazil, the ceramic tiles industry became wide during the 80 s decade, with a disconcentration industrial and regional pulverization. The competitiveness in the ceramic tiles internal and external consumers markets, it has debtor the industries to invest in sophisticated products each time more, either in design or the technology, but, mainly, in its final properties. Amongst the diverse types of ceramic coating, the porcelanato if has detached had to its process of technological production and excellent characteristics techniques. The Porcelanato is currently the material for coatings that presents the best technical and aesthetic features when compared with others ceramics found on the market. The chemical composition and the others raw materials characteristics have an importance that must to be ally to the inherent characteristics of fabrication process, essentially those related to the cycle of burning. This work had as purpose to develop formularizations of ceramic mass for production of porcelanato without glass coating, pertaining to the group BIa (text of absorption of water ≤ 0.5%) and with resistance superior mechanics 35MPa from raw materials characterized. The ceramic raw materials selected to the development of this study (A1 and A2 clays, feldspate, talc and quartz) were submitted to the following tests: X-ray fluorescence - chemical analysis determination; X-ray diffraction - Analysis of the stages mineralogics; Laser granulometry - size distribution of particles; and Differential thermal analysis - thermal behavior. Were performed tests of absorption of water, lineal retraction of it burns, apparent specific mass and rupture tension the flexing. The results had evidenced that the formularizations that had the A1 clay and talc on its composition were efficient for the porcelanato production remaining their technological characteristics inside of the intervals of variation desired by the Norms of the ABNT
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Traditional ceramics have an important role in the economy of Rio Grande do Norte. The local industries manufacture over 50 million shingles a month, corresponding to 60% of their overall production. As a result of processing flaws, roughly 20% of the production must be discarded, since little or no use has been envisaged for such fired components. Therefore, the use of this kind of residue, especially in the composition of other ceramic materials, comes as an interesting option from the economical and environmental point of view. In this scenario, the objective of the present study was to assess the effect of the addition of fired shingle waste in the composition of porcelainized stoneware tiles. To that end, two porcelainized stoneware tiles compositions were initially prepared. Subsequently, contents from 10 to 30% of roofing tiles chamote were added to each one of them. All raw materials and grog were characterized by FRX, XRD, and thermal analysis. The ceramics were fired using natural gas for 30 min at different temperatures, i.e. 1150, 1200 and 1250ºC, and fully characterized. The addition of roofing tiles chamote resulted in composition with superior properties compared to additive-free compositions. Porcelainized stoneware tiles products that fulfill required standards for practical applications were achieved
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The types of products manufactured calcium silicate blocks are very diversified in its characteristics. They include accessory bricks, blocks, products in dense material, with or without reinforcements of hardware, great units in cellular material, and thermal insulating products. The elements calcium silicate are of great use in the prefabricated construction, being formed for dense masses and hardened by autoclaving. This work has for objective develop formulations that make possible the obtaining of calcium silicate blocks with characteristics that correspond the specifications technical, in the State of the Rio Grande of the North, in finality of obtaining technical viability for use in the civil construction. The work studied the availability raw materials from convenient for the production of calcium silicate blocks, and the effect of variations of the productive process on the developed products. The studied raw materials were: the quartz sand from the city of São Gonçalo do Amarante/RN, and two lime, a hydrated lime and a pure lime from the city of Governador Dix-Sept Rosado/RN. The raw materials collected were submitted a testes to particle size distribution, fluorescence of X rays, diffraction of X rays. Then were produced 8 formulations and made body-of-test by uniaxial pressing at 36 MPa, and cured for 7 hours at about 18 kgf/cm2 pressing and temperature of approximately 180 °C. The cure technological properties evaluated were: lineal shrinkage, apparent density, apparent porosity, water absorption, modulus of rupture flexural (3 points), resistance compression, phase analysis (XRD) and micromorphological analysis (SEM). From the results presented the technological properties, was possible say that utilization of hydrated lime becomes more viable its utilization in mass limestone silica, for manufacture of calcium silicate blocks
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Chitin and chitosan are nontoxic, biodegradable and biocompatible polymers produced by renewable natural sources with applications in diverse areas such as: agriculture, textile, pharmaceutical, cosmetics and biomaterials, such as gels, films and other polymeric membranes. Both have attracted greater interest of scientists and researchers as functional polymeric materials. In this context, the objective of this study was to take advantage of the waste of shrimp (Litopenaeus vannamei and Aristeus antennatus) and crabs (Ucides cordatus) from fairs, beach huts and restaurant in Natal/RN for the extraction of chitin and chitosan for the production of membranes by electrospinning process. The extraction was made through demineralization, deproteinization, deodorization and deacetylation. Morphological analyzes (SEM and XRD), Thermal analysis (TG and DTG), Spectroscopy in the Region of the Infrared with Transformed of Fourier (FTIR) analysis Calorimetry Differential Scanning (DSC) and mechanical tests for traction were performed. In (XRD) the semicrystalline structure of chitosan can be verified while the chitin had higher crystallinity. In the thermal analysis showed a dehydration process followed by decomposition, with similar behavior of carbonized material. Chitosan showed temperature of maximum degradation lower than chitin. In the analysis by Differential Scanning Calorimetry (DSC) the curves were coherent to the thermal events of the chitosan membranes. The results obtained with (DD) for chitosan extracted from Litopenaeus vannamei and Aristeus antennatus shrimp were (80.36 and 71.00%) and Ucides cordatus crabs was 74.65%. It can be observed that, with 70:30 solutions (v/v) (TFA/DCM), 60 and 90% CH3COOH, occurred better facilitate the formation of membranes, while 100:00 (v/v) (TFA/DCM) had formation of agglomerates. In relation to the monofilaments diameters of the chitosan membranes, it was noted that the capillary-collector distance of 10 cm and tensions of 25 and 30 kV contributed to the reduction of the diameters of membranes. It was found that the Young s modulus decreases with increasing concentration of chitosan in the membranes. 90% CH3COOH contributed to the increase in the deformation resulting in more flexible material. The membranes with 5% chitosan 70:30 (v/v) (TFA/DCM) had higher tensile strength
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Wear mechanisms and thermal history of two non-conforming sliding surfaces was investigated in laboratory. A micro-abrasion testing setup was used but the traditional rotative sphere method was substituted by a cylindrical surface of revolution which included seven sharp angles varying between 15o to 180o. The micro-abrasion tests lead to the investigation on the polyurethane response at different contact pressures. For these turned counterfaces with and without heat treatment. Normal load and sliding speeds were changed. The sliding distance was fixed at 5 km in each test. The room and contact temperatures were measured during the tests. The polyurethane was characterized using tensile testing, hardness Shore A measurement, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Thermomechanical Analyze (TMA). The Vickers micro-hardness of the steel was measured before and after the heat treatment and the metallographic characterization was also carried out. Worn surface of polyurethane was analysed using Scanning Electron Microscope (SEM) and EDS (Electron Diffraction Scanning) microanalyses. Single pass scratch testing in polyurethane using indenters with different contact angles was also carried out. The scar morphology of the wear, the wear mechanism and the thermal response were analyzed in order to correlate the conditions imposed by the pressure-velocity pair to the materials in contact. Eight different wear mechanisms were identified on the polyurethane surface. It was found correlation between the temperature variation and the wear scar morphology.
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In recent decades, ceramic products have become indispensable to the technological development of humanity, occupying important positions in scientific production and consequently in industrial production. One area of the economy that continues to absorb large amounts of the products of this sector is Construction. Among the branches of the ceramic industry, there are the red ceramic industry which is traditionally the basis of that economic sector. Among the reasons for which the red ceramic industry became popular in the country, and specifically in Rio Grande do Norte, is the abundance of this raw material, easily found throughout the national territory. However, it appears that the red ceramic industry has deficiencies in technology and skilled labor, resulting in the production of ceramic goods with low added value. Among the factors that determine the quality of the ceramic products red has the proper formulation of the ceramic mass, the conformation and the firing temperature. Thus, the overall goal of this work is to study the mineralogical and technological properties, two clays from the region of the Wasteland Potiguar industrial ceramist. Therefore, the raw materials were characterized by analysis of Xray diffraction (XRD) analysis, X-ray fluorescence (XRF), particle size analysis (FA), scanning electron microscopy (SEM), optical microscopy (OM ), plasticity index (PI), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The technological properties of the material were analyzed by water absorption tests (AA%) porosity (% PA), the linear shrinkage (RT%), apparent density (MEA), loss on ignition (PF%) and flexural strength three points (TRF)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico
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Lubricant is responsible for reducing the wear on the friction protect the metal against oxidation, corrosion and dissipates excess heat, making it essential for the balance of a mechanical system, consequently prolonging the useful life of such a system. The origin of lubricating oils is usually mineral being extracted from the petroleum. But the search for a new source of production of lubricants and fuels it is necessary to meet future demands and reduce the possible environmental damage. For this reason, looking alternative means to produce certain products derived from petroleum, such as biodiesel, for example. Returning to the realm of lubricants, also one realizes this need for new raw materials for their production. Vegetable oil is a renewable resource and biodegradable, and its use entails advantages in environmental, social and economic. The development of this project aims to characterize the carnauba oil as a lubricant plant, or biolubricant. To analyze the oil carnauba tests as checking density, flash point, fire point, viscosity, viscosity, acid number, pH, copper corrosion, thermal conductivity and thermal resistivity were developed. In addition, for conducting the wear on the friction and the gradient of the system temperature, the analysis equipment is designed for wear on the friction. Based on these results, it is observed that the oil carnauba show good correlation to its application as biolubricant
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Thermal insulation is used to protect the heated or cooled surfaces by the low thermal conductivity materials. The rigid ricin polyurethane foams (PURM) are used for thermal insulation and depend on the type and concentration of blowing agent. Obtaining PURM occurs by the use of polyol, silicone, catalyst and blowing agent are pre -mixed, reacting with the isocyanate. The glass is reusable, returnable and recyclable heat insulating material, whose time of heat dissipation determines the degree of relaxation of its structure; and viscosity determines the conditions for fusion, operating temperatures, annealing, etc. The production of PURM composites with waste glass powder (PV) represents economical and renewable actions of manufacturing of thermal insulating materials. Based on these aspects, the study aimed to produce and characterize the PURM composites with PV, whose the mass percentages were 5, 10, 20, 30, 40 and 50 wt%. PURM was obtained commercially, while the PV was recycled from the tailings of the stoning process of a glassmaking; when the refining process was applied to obtain micrometer particles. The PURM + PV composites were studied taking into account the standard sample of pure PURM and the influence of the percentage of PV in this PURM matrix. The results of the chemical, physical and morphological characterization were discussed taking into account the difference in the microstructural morphology of the PURM+PV composites and the pure PURM, as well the results of the physicochemical, mechanical e thermophysical tests by values obtained of density, hardness, compressive strength, specific heat, thermal conductivity and diffusivity. In general, the structure of pure PURM showed large, elongated and regular pores, while PURM+PV composites showed irregular, small and rounded pores with shapeless cells. This may have contributed to reducing their mechanical strength, especially for PURM - PV50. The hardness and density were found to have a proportional relationship with the PV content on PURM matrix. The specific heat, thermal diffusivity and thermal conductivity showed proportional relationship to each other. So, this has been realized that the increasing the PV content on PURM matrix resulted in the rise of diffusivity and thermal conductivity and the decrease of the specific heat. However, the values obtained by the PURM composites were similar the values of pure PURM, mainly the PURM-PV5 and PURM-PV10. Therefore, these composites can be applied like thermal insulator; furthermore, their use could reduce the production costs and to preserve the environment
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The petroleum industry, in consequence of an intense activity of exploration and production, is responsible by great part of the generation of residues, which are considered toxic and pollutants to the environment. Among these, the oil sludge is found produced during the production, transportation and refine phases. This work had the purpose to develop a process to recovery the oil present in oil sludge, in order to use the recovered oil as fuel or return it to the refining plant. From the preliminary tests, were identified the most important independent variables, like: temperature, contact time, solvents and acid volumes. Initially, a series of parameters to characterize the oil sludge was determined to characterize its. A special extractor was projected to work with oily waste. Two experimental designs were applied: fractional factorial and Doehlert. The tests were carried out in batch process to the conditions of the experimental designs applied. The efficiency obtained in the oil extraction process was 70%, in average. Oil sludge is composed of 36,2% of oil, 16,8% of ash, 40% of water and 7% of volatile constituents. However, the statistical analysis showed that the quadratic model was not well fitted to the process with a relative low determination coefficient (60,6%). This occurred due to the complexity of the oil sludge. To obtain a model able to represent the experiments, the mathematical model was used, the so called artificial neural networks (RNA), which was generated, initially, with 2, 4, 5, 6, 7 and 8 neurons in the hidden layer, 64 experimental results and 10000 presentations (interactions). Lesser dispersions were verified between the experimental and calculated values using 4 neurons, regarding the proportion of experimental points and estimated parameters. The analysis of the average deviations of the test divided by the respective training showed up that 2150 presentations resulted in the best value parameters. For the new model, the determination coefficient was 87,5%, which is quite satisfactory for the studied system
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The nanostructures materials are characterized to have particle size smaller than 100 nm and could reach 1 nm. Due to the extremely reduced dimensions of the grains, the properties of these materials are significantly modified relatively when compared with the conventional materials. In the present work was accomplished a study and characterization of the molybdenum carbide, seeking obtain it with particles size in the nanometers order and evaluate its potential as catalyst in the reaction of partial methane oxidation. The method used for obtaining the molybdenum carbide was starting from the precursor ammonium heptamolybdate of that was developed in split into two oven, in reactor of fixed bed, with at a heating rate of 5ºC/min, in a flow of methane and hydrogen whose flow was of 15L/h with 5% of methane for all of the samples. The studied temperatures were 350, 500, 600, 650, 660, 675 and 700ºC and were conducted for 0, 60, 120 and 180 minutes, and the percent amount and the crystallite size of the intermediate phases were determined by the Rietveld refinement method. The carbide obtained at 660ºC for 3 hours of reaction showed the best results, 24 nm. Certain the best synthesis condition, a passivating study was accomplished, in these conditions, to verify the stability of the carbide when exposed to the air. The molybdenum carbide was characterized by SEM, TEM, elemental analysis, ICP-AES, TG in atmosphere of hydrogen and TPR. Through the elemental analysis and ICP-AES the presence carbon load was verified. TG in atmosphere of hydrogen proved that is necessary the passivating of the molybdenum carbide, because occur oxidation in room temperature. The catalytic test was accomplished in the plant of Fischer-Tropsch of CTGAS, that is composed of a reactor of fixed bed. Already the catalytic test showed that the carbide presents activity for partial oxidation, but the operational conditions should be adjusted to improve the conversion
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Actually, surveys have been developed for obtaining new materials and methodologies that aim to minimize environmental problems due to discharges of industrial effluents contaminated with heavy metals. The adsorption has been used as an alternative technology effectively, economically viable and potentially important for the reduction of metals, especially when using natural adsorbents such as certain types of clay. Chitosan, a polymer of natural origin, present in the shells of crustaceans and insects, has also been used for this purpose. Among the clays, vermiculite is distinguished by its good ion exchange capacity and in its expanded form enhances its properties by greatly increasing its specific surface. This study aimed to evaluate the functionality of the hybrid material obtained through the modification of expanded vermiculite with chitosan in the removal of lead ions (II) in aqueous solution. The material was characterized by infrared spectroscopy (IR) in order to evaluate the efficiency of modification of matrix, the vermiculite, the organic material, chitosan. The thermal stability of the material and the ratio clay / polymer was evaluated by thermogravimetry. To evaluate the surface of the material was used in scanning electron microscopy (SEM) and (BET). The BET analysis revealed a significant increase in surface area of vermiculite that after interaction with chitosan, was obtained a value of 21, 6156 m2 / g. Adsorption tests were performed according to the particle size, concentration and time. The results show that the capacity of removal of ions through the vermiculite was on average 88.4% for lead in concentrations ranging from 20-200 mg / L and 64.2% in the concentration range of 1000 mg / L. Regarding the particle size, there was an increase in adsorption with decreasing particle size. In fuction to the time of contact, was observed adsorption equilibrium in 60 minutes with adsorption capacity. The data of the isotherms were fitted to equation Freundlich. The kinetic study of adsorption showed that the pseudo second- order model best describes the adsorption adsorption, having been found following values K2=0,024 g. mg-1 min-1and Qmax=25,75 mg/g, value very close to the calculated Qe = 26.31 mg / g. From the results we can conclude that the material can be used in wastewater treatment systems as a source of metal ions adsorbent due to its high adsorption capacity
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Studies show the great influence of free radicals and other oxidants as responsible for aging and degenerative diseases. On the other hand, the natural phenolic compounds has shown great as antioxidants to inhibit lipid peroxidation and lipoxygenase in vitro. Among these, is highlighted trans-resveratrol ( 3,5,4 `- trihydroxystilbene ) phenolic compound , characterized as a polyphenol stilbene class. The vegetables popularly known as "Azedinha" (Rumex Acetosa) has trans-resveratrol in its composition and from this, the present work aimed to study on the supercritical extraction and conventional extraction (Soxhlet and sequential) in roots of Rumex Acetosa, evaluating the efficiency of extractive processes, antioxidant activity, total phenolic content and quantification of trans-resveratrol contained in the extracts. Extractions using supercritical CO2 as solvent, addition of co-solvent (ethanol) and were conducted by the dynamic method in a fixed bed extractor. The trial met a 23 factorial design with three replications at the central point, with the variable reply process yield and concentration of trans-resveratrol and pressure as independent variables, temperature and concentration of co-solvent (% v/v). Yields ( mass of dry extract / mass of raw material used ) obtained from the supercritical extraction ranged from 0,8 to 7,63 % , and the best result was obtained at 250 bar and 90 °C using the co-solvent 15% ethanol (% v/v). The value was calculated for YCER a flow rate of 1,0 ± 0,17 g/min resulting in 0,0469 CO2 ( g solute / g solvent ). The results of the mass yield varied between conventional extractions 0,78 % ( hexane) and 9,97 % (ethanol). The statistical model generated from the data of the concentration of trans-resveratrol performed as meaningful and predictive for a 95% confidence. GC analysis on HPLC (High Performance Liquid Chromatography), transresveratrol was quantified in all extracts and concentration values ranged between 0,0033 and 0,42 ( mg / g extract) for supercritical extracts and between 0,449 and 17,046 (mg / g extract) to conventional extractions and therefore, the Soxhlet extraction with ethanol for more selective trans-resveratrol than the supercritical fluid. Evaluation of antioxidant (radical method to sequester 2,2- diphenyl-1- picryl - hydrazyl - DPPH) the supercritical extracts resulted in EC50 values (concentration effective to neutralize 50% of free radicals) of between 7,89 and 18,43 mg/mL , while resulting in a Soxhlet extraction with EC50 values in the range of 6,05 and 7,39 mg/mL. As for quantification of the phenolic compounds (Method Spectrophotometer Folin-Ciocalteau) the supercritical extracts resulted in values between 85,3 and 194,79 mg GAE / g extract, whereas values derived from the Soxhlet extract resulted in values between 178,5 and 237,8 mg GAE / g extract. The high antioxidant activity can not be attributed solely to the presence of phenolic compounds, but the presence of other antioxidants in the existing Rumex acetosa
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Despite the relatively organized cashew (Anacardium occidentale L.) productive chain and the number of cashew derivatives found in the market, it is estimated that over 90% of the cashew peduncle is wasted. A possible strategy for a better commercial exploitation of this agroindustrial commodity would be the production of spray dried cashew pulp. Thus, this paper approaches the yellow cashew pulp spray drying process and the final product evaluation. Based on that, the shelf life of the spray dried cashew pulp packed in different packaging was evaluated. Drying was conducted in two drying temperatures (140 °C to 150 °C) and two concentrations of Arabic gum (AG, 15% and 25%), which summed four experimental groups. The drying performance was evaluated as well as the physicochemical characteristics (moisture, water activity, total soluble solids, pH, density, solubility, particle diameter, hygroscopicity, degree of caking, color, scanning electronic microscopy and X-ray diffraction), composition (protein, ash, fat and sugars) and bioactive and functional value (total phenolic compounds, carotenoids, ascorbic acid and antioxidant activity) of the final products. Results showed spray drying efficiency higher than 65% for all experiments, mainly for the C4 group (150 °C and 25% AG) which reached efficiency of 93.4%. It was also observed high solubility (94.7% to 97.9%) and the groups with lower hygroscopicity (5.8% and 6.5%) were those with the highest proportion of drying coadjuvant. The particle diameters ranged between 14.7 μm and 30.2 μm and increased with the proportion of AG. When comparing the product before and after spray drying, the drying impact was evident. However, despite the observed losses, dried yellow cashew showed high phenolic concentration (from 235.9 to 380.4 mg GAE eq / 100 g DM), carotenoids between 0.22 and 0.49 mg/100 g DM and remarkable ascorbic acid levels (852.4 to 1346.2 mg/100 g DM), in addition to antioxidant activity ranging from 12.9 to 16.4 μmol TE/ g DM. The shelf life study revealed decreased phenolic content over time associated to a slight water activity increase. Overall, our results unveil the technological and bioactive potential of dried yellow cashew as a functional ingredient to be used in food formulations or as a ready-to-use product. The technological approach presented here can serve as an efficient strategy for a rational use of the cashew apple, avoiding its current underutilization
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Eutrophication is a growing process present in the water sources located in the northeast of Brazil. Among the main consequences of these changes in trophic levels of a water source, stands out adding complexity to the treatment to achieve water standards. By these considerations, this study aimed to define, on a laboratory scale, products and operational conditions to be applied in the processing steps using raw water from Gargalheiras dam, RN, Brazil. The dam mentioned shows a high number of cyanobacteria, with a concentration of cells / ml higher than that established by Decree No. 518/04 MS. The same source was also considered by the state environmental agency in 2009 as hypereutrophic. The static tests developed in this research simulated direct filtration (laboratory filters) and pre-oxidation with chlorine and powdered activated carbon adsorption. The research included the evaluation of the coagulants aluminum hydrochloride (HCA) and alum (SA). The development of the research investigated the conditions for rapid mixing, the dosages of coagulants and pHs of coagulation by the drawing of diagrams. The interference of filtration rate and particle size of filtering means were evaluated as samples and the time of contact were tested with chlorine and activated carbon. By the results of the characterization of the raw water source it was possible to identify the presence of a high pH (7.34). The true color was significant (29 uH) in relation to the apparent color and turbidity (66 uH and 13.60 NTU), reflecting in the measurement of organic matter: MON (8.41 mg.L-1) and Abs254 (0.065 cm-1). The optimization of quick mix set time of 17", the speed gradient of 700 s-1 in the coagulation with HCA and the time of 20" with speed gradient of 800 s-1 for SA. The smaller particle sizes of sand filtering means helped the treatment and the variation in filtration rate did not affect significantly the efficiency of the process. The evaluation of the processing steps found adjustment in standard color and turbidity of the Decree nº 518/04 MS, taking in consideration the average values found in raw water. In the treatment using the HCA for direct filtration the palatable pattern based on the apparent color can be achieved with a dose of 25 mg L-1. With the addition of pre-oxidation step, the standard result was achieved with a reduced dose for 12 mgHCA.L-1. The turbidity standard for water was obtained by direct filtration when the dose exceeds 25 mg L-1 of HCA. With pre-oxidation step there is the possibility of reducing the dose to 20 mg L-1.The addition of CAP adsorption, promoted drinking water for both parameters, with even lower dosage, 13 mg L-1 of HCA. With coagulation using SA removal required for the parameter of apparent color it was achieved with pre-oxidation and 22 mgSA.L-1. Despite the satisfactory results of treatment with the alum, it was not possible to provide water with turbidity less than 1.00 NTU even with the use of all stages of treatment