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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
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Item Características físico-químicas de ácidos húmicos em diferentes etapas da vermicompostagem(Eclética Química, 2010) Reis, E. L.; Reis, C.; Brighenti, C. R. G.Amostras de materiais coletados em diferentes estádios de vermicompostagem foram submetidas a procedimentos de extração de ácidos húmicos. Técnicas de titulação potenciométrica, termogravimetria (DTG), difração de raios X e espectrofotometria no uv/visível e no infravermelho foram utilizadas no estudo desses materiais. Os dados de titulação foram submetidos ao ajuste por regressão não-linear, determinando-se, assim, cinco valores de pKa característicos de cinco classes de grupos tituláveis. Nas curvas DTG, foram observadas duas etapas, sendo a primeira característica da separação de estruturas alifáticas e, ou, alicíclicas e a segunda, a decomposição de estruturas aromáticas. A difratometria de raios X apresentou diferenças marcantes nos resultados, principalmente nos três primeiros picos onde parecem ocorrer reorganização estrutural e polimerização ao longo do processo de vermicompostagem. Os espectros do infravermelho não apresentaram diferenciação entre os espectros. Os valores da razão E4/E6 encontrados estão de acordo com os característicos dos ácidos húmicos, mas não fornecem informações que possam contribuir para a elucidação da estrutura e formação desses ácidos.Item Evaluation of aerobic and anaerobic biodegradability and toxicity assessment of real pharmaceutical wastewater from industrial production of antibiotics(Brazilian Journal of Chemical Engineering, 2016-07) Marcelino, R. B. P.; Andrade, L. N.; Starling, M. C. V. M.; Amorim, C. C.; Barbosa, M. L. T.; Lopes, R. P.; Reis, B. G.; Leão, M. M. D.This study evaluates aerobic and anaerobic biodegradability and toxicity of a real pharmaceutical wastewater, which focuses on antibiotics production. Zahn-Wellens and Organization for Economic Cooperation and Development (OECD) methodologies were applied in order to verify the wastewater's biodegradability and Microtox® analysis was performed for toxicity tests. Tests achieved more than 89% and 63% of Total Organic Carbon reduction, showing 80% and 50% of antibiotic removal, for aerobic and anaerobic processes, respectively. Moreover, acute ecotoxicological tests revealed that both techniques decreased the toxic character of real pharmaceutical wastewater. Desorption tests showed that the antibiotic was not degraded, but, in fact, adsorbed onto the sludge. Since biological treatment is the most widely used method for industrial wastewater treatment, this study indicates that this kind of treatment is probably unable to mineralize antibiotics present in pharmaceutical wastewaters, which may induce the development of resistant pathogens. Therefore, efforts must be taken to elucidate the main mechanisms of biological antibiotic removal from wastewaters since the presence of antibiotics in the environment is considered to be an emerging environmental issue.Item Synthesis and phytotoxicity of 4,5 functionalized tetrahydrofuran-2-ones(Journal of the Brazilian Chemical Society, 2012-12) Resende, Gabriela C.; Alvarenga, Elson S.; Galindo, Juan C. G.; Macias, Francisco A.In this work we report a versatile synthesis of fourteen γ-lactones all structurally related, nine of which are novel compounds, accomplished from the readily available furfural. The phytotoxic activity of the synthesized compounds was evaluated in vitro by the influence on the growth of wheat coleoptiles. The percentages of inhibition were mostly small and not statistically different from control after the third dilution (100 µmol L-1). In general, α,β-unsaturated lactones presented better activities than the saturated ones. The most active compounds presented 51, 68 and 76% of inhibition in 1000 µmol L-1. The results indicate that regardless of saturation, the presence of the γ-lactone moiety is important for the bioactivity, but their presence has no implications with potency.Item Remoção dos corantes Reactive Blue 21 e Direct Red 80 utilizando resíduos de sementes de Mabea fistulifera Mart. como biossorvente(Revista Ambiente & Água, 2012-01) Silveira Neta, Julieta de Jesus da; Silva, Carlos Juliano da; Moreira, Guilherme Costa; Reis, César; Reis, Efraim LázaroNeste estudo empregou-se resíduos de Mabea fistulifera Mart. como bioadsorvente para a remoção dos corantes Reactive Blue 21 (RB 21) e Direct Red 80 (DR 80) em soluções aquosas e em amostras de efluentes reais fortificados com estes corantes. Foram investigados os ensaios da influência do pH, cinéticos e adsortivos para a remoção dos corantes por meio de uma série de experimentos de batelada. O bioadsorvente exibiu máxima adsorção em pH = 2,0 para ambos os corantes. O tempo de equilíbrio da adsorção foi estabelecido em 300 minutos para o DR 80 e 120 minutos para o RB 21. O modelo de Langmuir descreveu com maior fidelidade o comportamento do sistema sortivo, apresentando coeficiente de determinação (R 2 ) superior a 0,98. Por meio da Isoterma de Langmuir, foi possível obter a capacidade máxima de adsorção dos corantes Direct Red 80 e Reactive Blue 21 pelo bioadsorvente sendo encontrados os valores de 4,92 mg g-1 e 11,13 mg g-1 , respectivamente. O modelo cinético de pseudo-segunda ordem melhor descreveu o processo de adsorção do corante RB 21 sob o bioadsorvente, embora a difusão intra-partícula também esteja envolvida no mecanismo de adsorção. Já para o corante DR 80 o modelo de difusão de Morris e Weber sugeriu que a difusão intra-partícula é predominante em todo o processo de adsorção. Depois de otimizadas as condições adsortivas, o bioadsorvente foi empregado a amostras de efluentes têxteis reais fortificadas com soluções aquosas dos corantes, obtendo-se 85 % de remoção do RB 21 e 94 % de remoção do DR 80 na matriz do efluente.Item Direct infusion esi-ms applied in the detection of byproducts due to reductive degradation of acetamiprid by zero-valent iron(Química Nova, 2015-09) Cruz, Jean C.; Reis, Marina F.; Salvador, Marília M.; Almeida, Marciano F.; Augusti, Rodinei; Lopes, Renata P.This study investigated the reductive degradation of acetamiprid (5 mg L-1) in aqueous medium (at pH 2.0) induced by zero-valent iron (50 mg). The process was monitored using high-performance liquid chromatography (HPLC) to determine the degradation rate as a function of reaction time, and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) to search for (and potentially characterize) any possible byproducts formed during degradation. The results obtained via HPLC showed that after 60 min, the degradation of the substrate reached nearly 100% in an acidic medium, whereas the mineralization rate (as determined by total organic carbon measurements) was as low as 3%. Data obtained by DI-ESI-MS showed that byproducts were formed mainly by insertions of hydrogen atoms into the nitrile, imine, and pyridine ring moieties, in addition to the observation of chlorine substitution by hydrogen replacement (hydrodechlorination) reactions.Item Influência do conteúdo de xilanas na branqueabilidade, propriedades higroscópicas, fisico-mecânicas e óptica de polpas branqueadas de eucalipto(Química Nova, 2015-02) Gomes, Valéria J.; Longue Jr, Dalton; Colodette, Jorge L.; Ribeiro, Robisnéa A.; Braun, HederBleached eucalypt kraft pulps are widely used in print and writing (P&W) and tissue paper manufacture. Among the quality requirements of pulp for these papers, xylan content has been controversial. The objective of this study was to evaluate the influence of xylan content on bleachability, hygroscopic, physic-mechanical and optical properties of the pulp. In this study industrial unbleached eucalyptus kraft pulp (15.6% xylans) treated with different NaOH loads to change its xylan content was used. Subsequently, pulps were bleached by the ODHT(EP)D sequence to achieve 90% ISO of brightness, then refined and submitted to hygroscopic, physicomechanical and optical tests. NaOH treatments decreased the xylan content to 14.5-5.9% using NaOH loads of 10-70 g L-1. Pulp bleachability was not significantly affected by xylan content decrease. The decrease in xylan content negatively affected the water retention value and Klemm capillarity of the pulp, while water absorption capacity was positively affected. Tensile and tear index were negatively influenced by the reduction in xylan content, whereas bulk and light scattering coefficient increased.Item Partição de proteínas de soro de leite em sistemas aquosos bifásicos baseados em líquidos iônicos(Química Nova, 2015-11) Michel, Benôit; Neves, Mateus Tomaz; Sousa, Rita de Cássia Superbi de; Chagas, Marcelo Martins das; Martins, Bruna Amaral; Coimbra, Jane Sélia dos ReisIn this work, we used an aqueous two-phase system (ATPS) consisting of the ionic liquid [C4mim][Cl] and the salt K2HPO4 to partition α-lactalbumin, β-lactoglobulin, and lactoferrin whey proteins. Extraction efficiency values above 87% indicate that the proteins primarily migrated to the ionic liquid-rich phase (top phase). Partition coefficient values ranged from 6.17 to 8.93 for a-lactalbumin, from 22.80 to 34.55 for β-lactoglobulin, and from 26.46 to 40.06 for lactoferrin. Therefore, the saline ATPS with the ionic liquid examined in this study can be considered to be a promising alternative for extracting whey proteins.Item Bis(4-fluorophenylsulfonyldithiocarbimato) zincate(ii) salts: new antifungals for the control of botrytis blight(Química Nova, 2015-07) Oliveira, Alexandre A.; Oliveira, Marcelo R. L.; Rubinger, Mayura M. M.; Piló, Elisa L.; Menezes, Daniele C.; Zambolim, LaércioBotrytis blight or gray mold is a highly destructive disease caused by Botrytis spp., that infects flowers, trees vegetables, fruit, especially grapevines and strawberry. Three new compounds with general formula (A)2[Zn(4-FC6H4SO2N=CS2)2], where A = PPh3CH3 (2a), PPh3C2H5 (2b), PPh3C4H9 (2c), and the previously published compounds where A = PPh4 (2d) and NBu4 (2e), were synthesized by the reaction of 4-fluorophenylsulfonyldithiocarbimate potassium dihydrate and zinc(II) acetate dihydrate with the appropriate counter cations (A) halides. The new compounds were characterized by infrared, 1H and 13C NMR spectroscopies. All these salts inhibited the growth of Botrytis cinerea, with compounds 2c and 2d showing greater antifungal activity than zinc dimethyldithiocarbamate, the active principle of the fungicide Ziram. The bis(dithiocarbimate)zincate(II) salts are also active against the bacteria Escherichia coli and Staphylococcus aureus.Item Mcr-als aplicado no monitoramento quantitativo do processo de eletrodegradação da atrazina usando espectros uv: resultados comparativos com hplc-dad como um método de referência(Química Nova, 2016-02) Souza, Thálisson S.; Zanin, Hudson G.; Peterlevitz, Alfredo; Baranauskas, Vitor; Silva, Gilmare A. da; Reis, César; Reis, Efraim L.; Teófilo, Reinaldo F.Electrodegradation of atrazine in water was performed using homemade (PA and PB) and purchased (PC) boron-doped diamond anodes. The degradation was monitored off-line by analyzing total organic carbon and high performance liquid chromatography with diode array detector (HPLC-DAD) and at-line by UV spectroscopy. The spectra were recorded every 2 min. The rank deficiency problem was resolved by assembling an augmented column-wise matrix. HPLC was employed to separate the original and byproducts degradation components. Aiming the same goal, multivariate curve resolution – alternating least squares (MCR-ALS) was applied to resolve the UV spectroscopic data. Comparison between HPLC and MCR-ALS separations is presented. By using MCR-ALS the spectra of atrazine and two byproducts were successfully resolved and the resulted concentration profiles properly represented the system studied. The ALS explained variance (R 2 ) for PA, PB and PC was equal to 99.99% for all of them and the lack of fit for PA, PB and PC were 0.39, 0.34 and 0.54 respectively. The correlation (R) between the recovered and pure spectra were calculate for each electrodegradation, validating the MCR-ALS results. The average R was equal to 0.997. The spectral and concentration profiles described with this new approach are in agreement with HPLC-DAD results. The proposed method is an alternative to classical analyses for monitoring of the degradation process, mainly due to the simplicity, fast results and economy.Item Síntese e caracterização de novos organometálicos de estanho (iv) com ligantes ditiocarbimatos e sua ação acceleradora na vulcanização de borracha nitrílica(Química Nova, 2016-08) Bottega, Fernanda C.; Oliveira, Marcelo R. L.; Sérvulo, Vanessa Pio; Visconte, Leila L. Y.; Ardisson, José D.; Rubinger, Mayura M. M.This paper describes the synthesis of four new organotin compounds of general formula: (Ph4P)[Sn(Cy)3(RSO2N=CS2)] [Ph4P = tetraphenylphosphonium cation, Cy = cyclohexyl, R = C6H5 (1), 4-ClC6H4 (2), 4-BrC6H4 (3) and 4-IC6H4 (4)]. They were obtained by the reaction between four different potassium N-R-sulfonyldithiocarbimate salts and tricyclohexyltin chloride in methanol, and were isolated as tetraphenylphosphonium salts. The elemental analyses of C, H, N and the data of high-resolution mass spectrometry were consistent with the proposed formulae. The 119Sn NMR spectra and 119Sn Mössbauer spectroscopic data were consistent with the presence of tetracoordinated tin(IV) species in solution and in the solid state. The electrolytic molar conductance and the integration curves in the 1H NMR spectra are in accord with the 1:1 proportion between the tetraphenylphosphonium cations and the complex anions. The activity of the new compounds in the vulcanization of nitrile rubber was evaluated and the results were compared to those achieved with the commercial accelerators: N-tert-butyl-2-benzothiazolesulfenamide (TBBS), tetramethylthiuram disulfide (TMTD) and zinc diethyldithiocarbamate (ZEDC).