Microencapsulation of Yarrowia lipolytica: cell viability and application in vitro ruminant diets.

Microencapsulation is an alternative to increase the survival capacity of microorganisms, including Yarrowia lipolytica, a widely studied yeast that produces high-value metabolites, such as lipids, aromatic compounds, biomass, lipases, and organic acids. Thus, the present study sought to investigate the effectiveness of different wall materials and the influence of the addition of salts on the microencapsulation of Y. lipolytica, evaluating yield, relationship with cell stability, ability to survive during storage, and in vitro application of ruminant diets. The spray drying process was performed via atomization, testing 11 different compositions using maltodextrin (MD), modified starch (MS) and whey protein concentrate (WPC), Y. lipolytica (Y. lipo) cells, tripolyphosphate (TPP), and sodium erythorbate (SE). The data show a reduction in the water activity value in all treatments. The highest encapsulation yield was found in treatments using MD + TPP + Y. lipo (84.0%) and WPC + TPP + Y. lipo (81.6%). Microencapsulated particles showed a survival rate ranging from 71.61 to 99.83% after 24 h. The treatments WPC + Y. lipo, WPC + SE + Y. lipo, WPC + TPP + Y. lipo, and MD + SE + Y. lipo remained stable for up to 105 days under storage conditions. The treatment WPC + SE + Y. lipo (microencapsulated yeast) was applied in the diet of ruminants due to the greater stability of cell survival. The comparison between the WPC + SE + Y. lipo treatment, wall materials, and the non-microencapsulated yeast showed that the microencapsulated yeast obtained a higher soluble fraction, degradability potential, and release of nutrients.

High-performance hydrophobic magnetic hydrotalcite for selective treatment of oily wastewater.

Oil emulsified in water is one of the most difficult mixtures to treat due to the good stability of emulsions, so there is a growing demand for more efficient methods for separating immiscible oil/water mixtures. In this context, the focus of this study was to obtain an adsorbent for the selective treatment of a simulated oily wastewater. To this aim, a modified hydrotalcite sample with hydrophobic and magnetic characteristics was prepared and characterized. Initially, the effect of sodium dodecyl sulfate (SDS) amount on the adsorbent characteristics was evaluated (266-800 mgSDS g-1LDH). The hydrophobic hydrotalcite (LDH-SDS) containing 533 mgSDS g-1LDH (LDH-SDS2) presented a higher interlayer space where the surfactant molecules were arranged perpendicular to the lamellae, allowing better access to the hydrotalcite pores and facilitating the selective adsorption of oil compounds. Moreover, the synergistic association of hydrophobic properties with super-wetting and effective adhesion oil to Fe3O4 favoured the selective adsorption of the simulated oily wastewater onto the hydrophobic and magnetic hydrotalcite (LDH-MSDS), facilitating the post-treatment separation. The kinetic analysis demonstrated that the adsorption equilibrium was attained in 120 min and the pseudo-second order model was the most suitable for predicting the removal of total organic carbon (TOC) from the simulated oily wastewater. The Langmuir model described very well the equilibrium experimental data, with a maximum adsorption capacity for TOC removal using LDH-MSDS of 659.9 mg g-1. Therefore, the modified hydrotalcite prepared in this study showed intrinsic characteristics that make it a promising adsorbent for the selective treatment of oily wastewaters.

Enzymatic synthesis of ascorbyl oleate and evaluation of biological activities.

Compounds that reduce or neutralize free radicals have been evaluated for use as nutraceutical or antioxidant additives in processed foods. This study aimed to enzymatically produce ascorbyl oleate and assess its biological properties. The synthesis was performed under previously maximized conditions (L-ascorbic acid/oleic acid 1:9 molar ratio, 70 °C, 1 h reaction). Immobilized commercial lipase from Candida antarctica (NS 88011) was used as biocatalyst. The reaction product was isolated, and its structure was confirmed by High-Performance Liquid Chromatography and Nuclear Magnetic Resonance. Ascorbyl oleate showed antioxidant and antimicrobial activity, besides no toxicity, did not influencing blood coagulation and also not presenting hemolytic profile. Better storage stability was achieved under refrigerated conditions, and the oxidative stability demonstrated free radicals fighting efficiency, increasing olive oil's shelf life. In vitro gastrointestinal simulation showed that ascorbyl oleate maintained antioxidant potential up to the duodenum stage during the digestive process. Therefore, the synthesized natural compound presented a high potential to be applied in the food and pharmaceutical industries.

Immobilization of Lipase from Candida antarctica B (CALB) by Sol-Gel Technique Using Rice Husk Ash as Silic Source and Ionic Liquid as Additive.

This work presents the immobilization in situ of commercial lipase from Candida antarctica B (CALB) by the sol-gel technique (xerogel) using silica from rice husk ash (RHA) as a source of silicon. It was used the Ionic Liquid (IL) 1-octyl-3-methylimidazolium bromide (C8MI.Br) as additive. The immobilized derivatives were characterized per SEM, XRD, and per method BET. The enzymatic activity of xerogels was evaluated with different tests, these being the reactional thermal analysis, immobilization yield, and operational and storage stability. The XDR showed that the obtained xerogels have halos in the region between 15 and 35° (2θ) what characterizes it as amorphous materials. The SEM analysis of xerogel shows irregular particles with dimensions less than 20 µm. The immobilized presented an esterification activity (EA) with 263.2 and 213.8 U/g, with and without IL, respectively, higher than the free enzyme (169.6 U/g). The immobilized, with and without IL, presented a significant improvement in the activity performance in relation to free enzyme for the three reactional temperatures (40, 60, and 80 °C) evaluated. The operational stability demonstrated that is possible to use xerogel without ionic liquid for 17 recycles and 21 recycles in IL presence. This methodology allows the preparation of new highly active and selective enzyme catalysts using the rice husk ash as a source of silicon, and the ionic liquid [C8MI]Br as additive. Furthermore, the new materials can provide greater viability in the processes, ensuring longer catalyst life.

In Situ Calb Enzyme Immobilization in Mesoporous Material Type MCM-48 Synthesis Using Ionic Solid [C14MI]Cl as Structure-Directing Agent.

MCM-48 mesoporous support was synthesized with the ionic solid 1-tetradecyl-3-methylimidazolium chloride ([C14MI]Cl) as a structure-directing agent for in situ immobilization of Candida antarctica B (CALB). The MCM-48[C14MI]Cl support showed characteristics of mesoporous material of interest, with a pore size of 20.30 and 73.41 A for the support without and with the enzyme, respectively. The elongation of the carbonic chain of the ionic solid directly influenced the increase in the specific area and pore volume of the material. In addition, the decrease in the specific area and pore volume for support with the enzyme showed the effectiveness of immobilization in situ. It was possible to obtain the ideal levels for the best activities of esterification of the enzyme with optimization of a mathematical model. The optimized variables were 0.31 g of enzyme and 3.35% of ionic solid with a maximum esterification activity of 392.92 U/g and 688% of yield. The support showed residual activity above 50% when stored under refrigeration for 75 days. At 60 and 80 °C, the enzyme immobilized on the support retained more than 80 and 40% of its residual activity, respectively. In addition, the support presented the possibility of reuse for up to 10 cycles with residual activity of approximately 50%. The support synthesized in the present study presents a great industrial opportunity for the immobilization and use of the CALB enzyme.

Evaluation of Different Ionic Liquids as Additives in the Immobilization of Lipase CAL B by Sol-Gel Technique.

Sol-gel technique aiming enzymatic immobilization in situ with ionic liquids as additives is poorly studied. In this process, the addition of the enzyme is carried out in the synthesis of the support. The characteristics of ionic liquids, such as low vapor pressure, thermal stability, and non-flammability, make them strong candidates for use as immobilization additives. The objective of the present study was to immobilize the Candida antarctica B lipase by the sol-gel technique using ionic liquids as additives. The optimum points determined for ionic liquids 1-butyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, and 1 hexadecyl-3-methylimimidazolium were 0.30, 0.27, and 0.22 g/mL of enzyme and 1.60, 1.52, and 1.52% of additive, respectively. The amount of enzyme and ionic liquids used in aerogel immobilization was the same as the optimized values in the xerogel immobilization process (for each ionic liquid). Ionic liquids proved to be good additives in the enzymatic immobilization process. Xerogel, regardless of the ionic liquid, presented a greater number of use cycles and better thermal stability compared to aerogel.

Nb-MCM-Type Mesoporous Material Synthesis Using Ionic Solid as Structure-Directing Agent for In Situ Lipase Immobilization.

MCM-41 and MCM-48 with niobium were successfully synthesized using 1-tetradecyl-3-methylimidazolium chloride ([C14MI]Cl) as a structure-directing agent. The best Si/Nb molar ratio was chosen (Si/Nb = 20) and the CALB enzyme was immobilized in situ in the synthesized Nb-MCM. SEM micrographs showed the formation of very regular spherical agglomerates with a diameter between 0.25 and 0.75 µm. The material presented a surface area of 954 and 704 m2/g and a pore volume of 0.321 and 0.286 cm3/g, for Nb-MCM-41 and Nb-MCM-48, respectively. Also, both materials showed a pore size of 2.261 nm. The number of recycles obtained for the CALB enzyme immobilized in Nb-MCM-41 and Nb-MCM-48 was 26 recycles with a residual activity of 49.62% and 16 recycles with a residual activity of 53.01%, respectively. For both materials, enzymatic activity remained stable for 5 months of storage at room temperature and refrigeration. The supports were able to catalyze the esterification reaction at 40, 60, and 80 °C, showing industrial application in reactions that require high temperatures. This methodology allows the preparation of new highly active and selective enzyme catalysts using niobium and [C14MI]Cl. Also, the new materials can provide greater viability in processes, ensuring a longer service life of catalysts. Graphical abstract.

Production of benzyl cinnamate by a low-cost immobilized lipase and evaluation of its antioxidant activity and toxicity.

In this work was optimized the production of benzyl cinnamate by enzymatic catalysis using the immobilized lipase NS88011 and to evaluate its biological properties. The optimized condition for this system was 1:3 (acid:alcohol) molar ratio, 59 °C, biocatalyst concentration 4.4 mg.mL-1 for 32 h, with a yield of 97.6 %. The enzyme stability study showed that the enzyme remains active and yields above 60 % until the 13th cycle (416 h), presenting a promising half-life. In the determination of the antioxidant activity of the ester, an inhibitory concentration necessary to inhibit 50 % of the free radical 2,2-diphenyl-1-picryl-hydrazyl DPPH (IC50) of 149.8 mg.mL-1 was observed. For acute toxicity against bioindicator Artemia salina, lethal doses (LD50) of 0.07 and 436.7 µg.mL-1 were obtained for the ester and cinnamic acid, showing that benzyl cinnamate had higher toxicity, indicating potential cytotoxic activity against human tumors.

Development and characterization of light yoghurt elaborated with Bifidobacterium animalis subsp. Lactis Bb-12 and fructooligosaccharides / Desenvolvimento e caracterização de iogurte light elaborado com Bifidobacterium animalis subsp. Lactis Bb-12 e fruto-oligossacarídeos

ABSTRACT: This study aimed to evaluate the effects of adding probiotic culture (Bifidobacterium animalis subsp. Lactis Bb-12) and prebiotics (fructooligosaccharide - FOS) to yoghurt formulations stored at 4°C for 28 days, using an experimental design (independent variables: (0-3% of FOS and probiotic starter cultures 0-3%). The pH, acidity, fat, syneresis, protein, ºBrix, sugars, FOS and probiotic bacteria count were analyzed. The probiotic- and prebiotic-added yoghurt formulations showed lower acidity, syneresis and glucose than the control yoghurt and compared to formulations containing probiotic and prebiotic separately. The 3% probiotic and prebiotic formulation showed a lower loss of concentration of FOS, and after 28 days presented 1.5g of FOS per 100g (0.3% kestose, 0.7% nystose, 0.5% fructosyl-nystose). Furthermore, the addition of prebiotics exerted a protective effect on probiotic bacteria, enhancing their survival.

RESUMO: Este estudo teve como objetivo avaliar os efeitos da adição de cultura probiótica (Bifidobacterium animalis subsp. Lactis Bb-12) e prebióticos (fructooligosacarídeo - FOS) a formulações de iogurte armazenadas a 4°C por 28 dias, utilizando um planejamento experimental (variáveis independentes: (0-3% de FOS e cultura probiótica starter 0-3%). Foram analisados pH, acidez, gordura, sinérese, proteína, ºBrix, açúcares, FOS e contagem de bactérias probióticas. As formulações de iogurte adicionado de probiótico e prebiótico apresentaram menor acidez, sinérese e glicose quando comparados ao iogurte controle e também em comparação com as formulações contendo probiótico e prebiótico sozinhas. A formulação com 3% de probiótico e prebiótico apresentou menor perda de concentração de FOS e, após 28 dias, apresentou 1,5g de FOS por 100g (0,3% de kestose, 0,7% de nystose , 0,5% de fructosil-nistose). Além disso, a adição de prebióticos exerceu um efeito protetor sobre as bactérias probióticas e aumentou a sua sobrevivência.

Production and purification of amylolytic enzymes for saccharification of microalgal biomass.

The aim of this study was the production of amylolytic enzymes by solid state or submerged fermentations (SSF or SF, respectively), followed by purification using chemical process or microfiltration and immobilization of purified enzymes in a polyurethane support. The free and immobilized enzymes obtained were used to evaluate enzymatic hydrolysis of the polysaccharides of Spirulina. Microfiltration of the crude extracts resulted in an increase in their specific activity and thermal stability at 40°C and 50°C for 24h, as compared to extracts obtained by SSF and SF. Immobilization of polyurethane purified enzyme produced yields of 332% and 205% for the enzymes obtained by SF and SSF, respectively. Free or immobilized enzymes favor the generation of fermentable sugar, being the application of the purified and immobilized enzymes in the hydrolysis of microalgal polysaccharides considered a promising alternative towards development of the bioethanol production process from microalgal biomass.

Biomimetic Mineralization of the Alginate/Gelatin/Calcium Oxalate Matrix for Immobilization of Pectinase: Influence of Matrix on the Pectinolytic Activity.

Pectinases catalyze the degradation of pectic substances and are used in several processes, mainly in food and textile industries. In this study, a biomimetic matrix of alginate/gelatin/calcium oxalate (AGOCa) was synthesized for the in situ immobilization via encapsulation of crude pectinase from Aspergillus niger ATCC 9642, obtaining an immobilization efficiency of about 61.7 %. To determine the performance of AGOCa matrix, this was compared to control matrices of alginate/calcium oxalate (AOxal) and alginate/water (ACa). By the evaluation of pH and temperature effects on the enzyme activity, it was observed an increase on pectinolytic activity for both three tested matrices with an increase on pH and temperature. The kinetic parameters for pectinase immobilized in the three matrices were determined using citric pectin as substrate. Values of K m of 0.003, 0.0013, and 0.0022 g mL(-1) and V max of 3.85, 4.32, and 3.17 µmol min(-1) g(-1) for AGOCa, AOxal, and ACa matrices were obtained, respectively. After 33 days of storage, the pectinase immobilized in the three different matrices kept its initial activity, but that immobilized in AGOCa presented high stability to the storage with a relative activity of about 160 %. The enzyme immobilized in AGOCa, AOxal, and ACa could be used in 10, 8, and 7 cycles, respectively, keeping 40 % of its initial activity.

Interference of salts used on aqueous two-phase systems on the quantification of total proteins.

In this study the interference of potassium phosphate, sodium citrate, sodium chloride and sodium nitrate salts on protein quantification by Bradford's method was assessed. Potassium phosphate and sodium citrate salts are commonly used in aqueous two-phase systems for enzyme purification. Results showed that the presence of potassium phosphate and sodium citrate salts increase the absorbance of the samples, when compared with the samples without any salt. The increase in absorptivity of the solution induces errors on protein quantification, which are propagated to the calculations of specific enzyme activity and consequently on purification factor. The presence of sodium chloride and sodium nitrate practically did not affect the absorbance of inulinase, probably the metals present in the enzyme extract did not interact with the added salts.

Synthesis of a hybrid polymer-inorganic biomimetic support incorporating in situ pectinase from Aspergillus niger ATCC 9642.

The hybrid alginate/gelatin/calcium oxalate (AGOCa) support was successfully synthesized through the biomimetic mineralization method for immobilization in situ of a pectinolytic extract from Aspergillus niger ATCC 9642 via entrapment technique. The efficiency of immobilization reached 72.7%. Sodium oxalate buffer (100 mM, pH 5.5) was selected as adjuvant of the immobilization process by allowing the formation of a calcified shell around the calcium alginate capsule, significantly increasing the stability to storage, thermal and recycling of the enzymatic immobilized pectinolytic extract. The pH and temperature for maximum activity were from 5.0 to 6.0 and 60 to 80 °C, respectively. The new hybrid support can be a potential alternative to obtain immobilized pectinases with properties for advantageous industrial applications.

Analysis of volatile compounds of Ilex paraguariensis A. St. - Hil. and its main adulterating species Ilex theizans Mart. ex Reissek and Ilex dumosa Reissek / Análise de compostos voláteis de Ilex paraguariensis A. St. - Hil. e suas principais espécies adulterantes Ilex theizans Mart. ex Reissek e Ilex dumosa Reissek

The adulteration of the product Ilex paraguariensis with other Ilex species is a mAjor problem for maté tea producers. In this work, three species of Ilex were evaluated for their volatile composition by headspace solid phase microextraction coupled to gas chromatography and mass spectrum detector (HS-SPME/GC-MS). The adulterating species I. dumnosa and I. theizans Mart. ex Reissek presented a different profile of volatile organic compounds when compared to I. paraguariensis. Aldehydes methyl-butanal, pentanal, hexanal, heptanal and nonanal were detected only in the adulterating species. This result suggests that such compounds are potential chemical markers for identification of adulteration and quality analysis of products based on Ilex paraguariensis.

A adulteração do produto Ilex paraguariensis com outras espécies de Ilex é um dos principais problemas dos produtores de erva-mate. Neste trabalho, três espécies de Ilex foram avaliadas quanto à sua composição volátil por microextração em fase sólida acoplada à cromatografia gasosa e detector de espectro de massas (HS-SPME/GC-MS). As espécies adulterantes I. dumnosa e I. theizans Mart. ex Reissek apresentaram um perfil diferente de compostos orgânicos voláteis, quando comparadas com a I. paraguariensis. Os aldeídos metil-butanal, pentanal, hexanal, heptanal e nonanal foram detectados apenas nas espécies adulterantes. Esse resultado sugere que esses compostos químicos são marcadores potenciais para a identificação de adulteração e análise da qualidade dos produtos à base de Ilex paraguariensis.

Toxicidade animal por formaldeídeo e complucad® em ratos wistar: exposição aguda / Animal toxicity caused by formaldehyde and complucad® in wistar rats: acute exposure

Objetivos: Verificar a toxicidade em ratos Wistar expostos ao formaldeídeo a 10% e Complucad®, analisando-se as enzimas hepáticas alaninaaminotransferase e aspartatoaminotransferase, os tecidos pulmonar, renal e hepático, após período de exposição aguda. Métodos. A amostra contou com 24 ratos machos adultos, da linhagem Wistar-Tecpar, divididos aleatoriamente em três grupos com oito animais cada. O Grupo Controle Negativo (G.C), não foi exposto às substâncias. O Grupo Controle Positivo (G.F) foi exposto ao formaldeído a 1.33 ppm e o Grupo Experimental (G.CP) exposto à substância Complucad®. Os animais foram mantidos sob condições normais de temperatura, com fotoperíodo de 12h claro/escuro, alimentados com ração balanceada para roedores e água ad libitum, sendo expostos diariamente (8 horas/dia) às respectivas substâncias. Após o período de exposição os mesmos foram anestesiados para coleta sanguínea, seguida de eutanásia para coleta dos tecidos. Resultados: O teste ANOVA seguido de TUKEY realizado com nível de significância de 5% demonstrou para a enzima alanina diferença (p=0,04) entre o G.F quando comparado ao controle. A enzima aspartato apresentou (p=0,20). A avaliação histológica dos órgãos demonstrou alteração significativa para o tecido hepático sendo (p=0,0001), tecido pulmonar (p=0,0085) e tecido renal (p=0,00), mediante o teste estatístico com Qui-Quadrado. Através da aplicação do teste Kruskall Wallis 5% para as variáveis dos tecidos, observou-se infiltração de células e perda da arquitetura (p<0,03), dilatação alveolar (p=0,01), tumefação celular cortical, congestão vascular cortical e dilatação tubular (p<0,01). Conclusão: Houve grau de toxicidade aos referidos xenobióticos, sendo em maior intensidade no grupo exposto ao formaldeídeo a 10%.

Objectives: Verify the toxicity in Wistar rats exposed to formaldehyde solutions at 10% and Complucad®, analyzing the alaninaaminotransferase/aspartatoaminotransferase hepatic enzymes and the lung, kidney and liver tissues, after a sharp period of exposition. Methods: The 24 Wistar-Tecpar adult male rats, divided randomly into three groups, with eight animals each group. The Negative Control Group (G.C) was not exposed to the substances; the Positive Control Group (G.F) was exposed to formaldehyde at 1.33 ppm, and the Experimental Group (G. CP) was exposed to Complucad®. The animals were kept under room temperature, in a 12 hour light/dark photo period, fed with a balanced diet for rodents and ad libitum water, being daily exposed (8 hours a day) to the respective substances. After a period of exposition, they were anesthetized for blood collection, then the euthanasia for tissue collection. Results: the ANOVA followed by TUKEY performed with a significance level of 5% showed for enzyme alanine (p=0,04) between the G.F compared with the control group. The enzyme aspartate, showed (p=0,20). The organs histological evaluation showed a significant alteration for the liver tissue, being (p=0,0001), lung tissue (p=0,085), and kidney tissue (p=0.00), before treatment with the Qui-Quadrado Test. Applying the test Kruskall Wallis 5% for the variables of the tissues, observed, cell infiltration and loss of architecture (p=0,03), dilated alveolar (p=0,01), cortical cell swelling, cortical vascular congestion and dilatation tubular (p<0,01). Conclusion: There was a degree of toxicity to the referred xenobiotic, being more intense on the group exposed to formaldehyde at 10%.

Degradation of dimethyl disulfide using homogeneous Fenton's reaction.

In this work the degradation of a model odor compound (dimethyl disulfide, DMDS) using Fenton's reaction is reported. Dimethyl disulfide is present in wastewaters generated during production of poultry feather and viscera meal. Oxidation was carried out in batch reactor with temperature control. Experimental design technique was used to investigate the influence of concentration of hydrogen peroxide and Fe(2+), temperature and pH on degradation of DMDS. Control reactions using H(2)O(2) without Fe(2+) were carried out, but DMDS degradation could only reach 60% for a 0.025 mg L(-1) DMDS solution, at pH 3, 60 degrees C using 10,000 mg L(-1) H(2)O(2) in 30 min of reaction. The Fenton's reaction could effectively remove DMDS, reaching 95% degradation at pH 3, 60 degrees C, 5 mg L(-1) H(2)O(2) and 1 mg L(-1) Fe(2+) after only 10 min of contact. A kinetic study of the Fenton's reaction was carried out, varying the concentration of hydrogen peroxide, Fe(2+) and temperature.

Extração e recuperação de prata e mercúrio em efluentes gerados na determinação de DQO empregando métodos físico-químicos / Extraction and recovery of silver and mercury from COD-test residues using physico-chemical methods

Durante as análises de Demanda Química de Oxigênio (DQO) é gerado um efluente líquido que se caracteriza pela presença de elevadas concentrações de metais pesados (Hg, Ag, Cr e Fe). Visando à remoção seletiva destes metais, possibilitando suas reutilizações, foram avaliados diferentes agentes precipitantes (Cl-, Br-, I- e S= para a Ag e o Hg e NaOH, NH4OH e NaHCO3 para o Cr e o Fe). Para a Ag e o Hg os melhores resultados em termos de remoção e recuperação seletiva foram obtidos quando do emprego seqüencial dos íons cloreto e sulfeto. Devido à presença de Hg(I), se fez necessário o emprego de NH4OH para separar seletivamente a Ag, presente na forma de AgCl, precipitada concomitantemente com Hg(I) como Hg2Cl2. Para o Cr e o Fe foram obtidas remoções que satisfazem à legislação (FEPAM) para ambos os elementos, somente quando do emprego do NaOH como agente precipitante.

In the analysis of Chemical Oxygen Demand (COD) a liquid residue rich in heavy metals (Hg, Ag, Cr, Fe) is obtained. This work aimed to remove, in a selective way, such metals from the residue using chemical precipitation, also creating a possibility to recover and reuse the heavy metals,. Different precipitants were evaluated (Cl-, Br-, I- and S= for Ag and Hg, and NaOH, NH4OH and NaHCO3 for Cr and Fe). The best results for selective recovery of Ag and Hg were obtained using chloride followed by sulphide. Due to the presence of Hg(I) it is necessary the use of NH4OH to separate Ag and Hg(I) that are both precipitated as AgCl and Hg2Cl2. Removal of Cr and Fe that attends the local limits set by the official control agency (FEPAM) was only obtained when NaOH was used as precipitating agent.

Produção de carvão a partir de resíduo de erva-mate para a remoção de contaminantes orgânicos de meio aquoso / Production of charcoal from maté waste to remove organic contaminants from aqueous solution

Neste trabalho, apresenta-se um novo material adsorvente, obtido a partir da pirólise de resíduos da erva-mate. O carvão resultante demonstrou elevada área superficial específica quando comparado com outros materiais pirolisados e elevada capacidade de remoção de contaminantes orgânicos de soluções aquosas. Os valores de área específica apresentados pelos materiais foram de 344, 191 e ~0,5 m² g-1, para o carvão Mate 1, Mate 2 e Mate 3, respectivamente. As isotermas de adsorção mostraram que os carvões apresentam potencial para utilização como adsorvente para compostos orgânicos, tais como: o corante têxtil vermelho reativo, o corante azul de metileno e para o herbicida atrazina, sendo que os máximos de adsorção utilizando o carvão Mate 1 foram de 16, 230 e 30 mg g-1, respectivamente.

In this work we present a new adsorbent material, obtained by maté waste pyrolisis. The resulting charcoal presented high specific area when compared with other pyrolized materials and also high capacity to remove organic contaminants from aqueous solution. The charcoal showed specific area of 344, 191 and ~0.3 m² g-1 for sample Mate 1, Mate 2 and Mate 3, respectively. According to the corresponding adsorption isotherm these materials present good adsorption capacity for reactive textile and methylene blue dyes and the herbicide atrazine. Adsorption maxima were respectively 16, 230 and 35 mg g-1 for such substances, when sample Mate 1 was used.

Qualitative study of organic compounds in wastewaters of a swine slaughterhouse.

The main purpose of this work was the preliminary qualitative study of organic compounds in wastewaters of swine slaughterhouses. The samples were collected in a local abattoir and submitted to Liquid-Liquid Extraction (LLE) and Solid-phase Extraction (SPE) with XAD-4 resin as stationary phase. The instrumental analysis was performed by Gas Chromatography with Mass Spectrometer Detector (GC/MSD). The compounds present in the LLE and SPE extracts were identified by the GC/MSD library (Wiley). The results pointed out that SPE and LLE can extract practically the same classes of compounds at the same amounts. LLE works well for the extraction of polar organic compounds, with acidified samples, while SPE presents a better performance for the extraction of less polar organic compounds. Aldehydes were main class of the compounds extracted by SPE and LLE and decenal was the major aldehyde identified. Fatty alcohols and carboxylic acids were also identified but in minor proportions.

Determinaçäo de resíduos de carbofuran em vegetais por cromatografia líquida de alta eficiência (HPLC) / Carbofuran residues determination in vegetables by high efficiency liquid chromatography (HPLC)

O pesticida carbofuran (2,3-dihydro-2,2-dimethyl-7-benzo-furanyl-N-methylcarbamate) é um inseticida-nematicida de amplo espectro de aplicaçao, sendo empregado em escala crescente em muitos países tropicais, devido a sua eficácia contra numerosos insetos e pestes de frutas, vegetais e graos. Apresenta natureza polar e aromaticidade que tornam a determinaçao por HPLC com detecçao no UV atrativa. A análise foi efetuada em cromatógrafo Shimadzu com detector espectrofotométrico ajustado em 275 nm. Na separaçao foi empregada uma coluna Nucleosil C-18 (250 x 4 mm, 5 mum) e metanol-água (50:50, v/v; l mL/min). O volume injetado foi de 20 muL. A eficiência do procedimento foi investigada com amostras de tomate e batata fortificadas com carbofuran em O,1 e 1,0 mg/kg. As amostras foram trituradas em metanol. Após procedeu-se extraçao líquido-líquido com diclorometano. Para remover coextrativos ácidos foi empregada lavagem com hidróxido de sódio diluído. As recuperaçoes variaram entre 94,7 e 98,3 por cento para tomate e entre 95,3 e 97,2 por cento para batata. O limite de detecçao de O,14 mg/L corresponde a concentraçao mínima detectável de O,01l mg/kg em vegetais após a extraçao de 25 g de amostra. Estes resultados indicam o grande potencial do método descrito na determinaçao de resíduos de carbofuran nos vegetais estudados.