Processos avançados de oxidação de compostos fenólicos em efluentes industriais

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.

Otimização de metodologia para derivação de desoxinivalenol através de planejamento experimental

The objective of this work was to optimize the derivatization reaction for determining deoxynivalenol (DON) by gas chromatography employing an experimental planning procedure. The factors were: temperature, reaction time, catalyst and trifluoroacetic anhydride concentration. The relative peak areas were used to evaluated the effects. The best conditions for DON derivatization were 200 µL TFAA and 18 mg sodium bicarbonate for 6 min at 74 ºC for 7 to 21 µg of DON. Under these conditions, the detection limit was 1.4 µg of DON.

Síntese de padrões cromatográficos e estabelecimento de método para dosagem da composição de ésteres de ácidos graxos presentes no biodiesel a partir do óleo de babaçu

Several alkyl esters were synthesized, purified, characterized by ¹H NMR and employed as standards for establishing chromatographic methods to monitor their formation in the synthesis of biodiesel. The efficiency of the chromatographic methods was confirmed with the products of enzymatic transesterification of babassu oil with different alcohols (C2 to C4), using Lipozyme as catalyst.

Efeito de microondas na estrutura cristalina e na atividade catalítica de argilas

The effect of microwave (MW) irradiation on the crystalline structure of two natural clays and one commercial clay, Montmorillonite K10, was analyzed comparing the X-ray diffraction, N2 isotherms, NMR-MAS of 27Al and 29Si spectra of the clays before and after MW irradiation. The preparation of dioxolane ketals of isatin was used to analyze the MW effect on the catalyst activation. The yields achieved using catalysts activated by MW irradiation were lower (2 to 5%) than the yields achieved using catalysts activated by heat in a conventional oven.

Síntese de 1-indanonas através da reação de acilação de Friedel-Crafts intramolecular utilizando NbCl5 como ácido de Lewis

The intramolecular Friedel-Crafts acylation reaction of 3-arylpropanoic acids to give 1-indanones can be effected in good yields under mild conditions (room temperature) by using niobium pentachloride. Our results indicate that NbCl5 acts both as reagent (to transform carboxylic acids into acyl chlorides) and as catalyst in the Friedel-Crafts cyclization.

HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

Epoxidação do óleo de mamona e derivados empregando o sistema catalítico VO(acac)2/TBHP

The alternative system VO(acac)2/TBHP was investigated for the epoxidation reaction of castor oil and its derivatives. Results of 88% of conversion, 73% of epoxidation and 82% of selectivity were obtained for the system containing 20% excess of TBHP and 1% of VO(acac)2 catalyst, during 3 h under toluene reflux. The product was characterized by GC/MS as methyl-cis-9, 10-epoxi, 12-hydroxystearate and quantitative ¹H NMR was used to calculate the data above. Preliminary results indicate that the heterogeneous system VO(acac)2 grafted on K10 clay can also promote epoxidation of castor oil.

Palveluväylän hyödyntäminen palvelukeskeisessä arkkitehtuurissa

Palvelukeskeinen arkkitehtuuri on uusi tapa rakentaa tietojärjestelmiä. Se perustuu siihen, että logiikasta koostetaan yleiskäyttöisiä palveluita, joita tarjotaan muiden järjestelmän osien käyttöön. Tällöin samoja asioita ei tarvitse toteuttaa moneen kertaan ja järjestelmää voidaan hyödyntää tehokkaasti ja monipuolisesti. Näiden palveluiden hallinnassa voidaan hyödyntää palveluväyliä, eli ESB -tuotteita. Palveluväylät sisältävät erilaisia mekanismeja, joiden avulla palveluihin liittyvää viestiliikennettä voidaan reitittää, muokata ja valvoa eri tavoin. Nykyisissä palvelukeskeisissä toteutuksissa käytetään usein XML -kieleen pohjautuvia Web Service -määrityksiä. Ne tarjoavat ympäristöriippumattoman pohjan, joka täyttää suoraan useita palvelukeskeisen arkkitehtuurin vaatimuksia. Määritysten ympärille on myös paljon valmiita laajennuksia, joiden avulla palveluihin voidaan liittää lisätoiminnallisuutta. Lahden kaupunki lähti Fenix -projektin yhteydessä kehittämään uutta kuntien käyttöön soveltuvaa järjestelmää, joka hyödyntää palvelukeskeisen arkkitehtuurin periaatteita. Järjestelmä jaettiin selkeisiin kerroksiin siten, että käyttöliittymä erotettiin palvelulogiikoista palveluväylän avulla. Tällöin järjestelmä saatiin jaettua loogisiin kokonaisuuksiin, joilla on selkeä rooli. Taustapalvelut hoitavat käsitteiden hallinnan, sekä niihin liittyvät liiketoimintasäännöt. Käyttöliittymäkerros hoitaa tiedon esittämisen ja tarjoaa graafisen, selainpohjaisen käyttöliittymän palveluihin. Palveluväylä hoitaa liikenteen reitittämisen, sekä huolehtii palveluihin liittyvistä käyttöoikeuksista ja tilastoinnista. Lopputuloksena on loputtomiin laajennettavissa oleva järjestelmä, jonka päälle voidaan kehittää erilaisia sähköisiä palveluita kunnan ja sen asukkaiden välille.

Determinação de paládio em amostras biológicas aplicando técnicas analíticas nucleares

This study presents Pd determinations in bovine tissue samples containing palladium prepared in the laboratory, and CCQM-P63 automotive catalyst materials of the Proficiency Test, using instrumental thermal and epithermal neutron activation analysis and energy dispersive X-ray fluorescence techniques. Solvent extraction and solid phase extraction procedures were also applied to separate Pd from interfering elements before the irradiation in the nuclear reactor. The results obtained by different techniques were compared against each other to examine sensitivity, precision and accuracy.

Alargamento da distribuição de massa molar de polímeros sintetizados com catalisadores metalocênicos dual-site

The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest.

Síntese, caracterização e avaliação catalítica de Vo x/Mg yAlo x na reação de decomposição do isopropanol

Vanadium oxide supported on hydrotalcite-type precursors was studied in the decomposition of isopropanol. Hydrotalcite-type compounds with different y = Mg+2/Al+3 ratios were synthesized by the method of coprecipitating nitrates of Mg+2 and Al+3 cations with K2CO3 as precipitant. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene.

Imobilização de enzimas em suportes cromatográficos: uma ferramenta na busca por substâncias bioativas

The development and characterization of bioreactors or IMER (immobilized enzyme reactors) as research tools are important in the scope of medicinal chemistry and constitute an alternative for the rational development of drugs. This approach does not require highly purified enzymes or a great amount of protein, but increase the enzymatic stability against heat, organic solvents and pH, without too much loss of catalyst activity. Immobilized enzyme reactors (IMER) can be used for the accomplishment of high efficiency screening on-line and, thus inhibitors can be quickly identified. Here, we emphasize the development of IMER by use of different methods of immobilization and chromatographic supports. Their applications, in different areas of research, are also fully discussed.

Interesterificação química de óleo de soja e óleo de soja totalmente hidrogenado: influência do tempo de reação

Chemical interesterification is an important alternative to produce zero trans fats. In practice, however, excessive reaction times are used to ensure complete randomization. This work evaluated the influence of the reaction time on the interesterification of soybean oil/fully hydrogenated soybean oil blend, carried out in the following conditions: 100 ºC, 500 rpm stirring speed, 0.4% (w/w) sodium methoxide catalyst. The triacylglycerol composition, solid fat content and melting point analysis showed that the reaction was very fast, reaching the equilibrium within 5 min. This result suggests the interesterification can be performed in substantially lower times, with reduction in process costs.

Óxidos do tipo perovskita para reação de redução de no com CO

In this work, the perovskite-type oxides LaNiO3, LaMnO3, La0,7Sr0,3NiO3 and La0,7Sr0,3MnO3 were prepared by co-precipitation and tested in the NO reduction with CO at 400 and 500 ºC for 10 h. The catalysts were characterized by X-ray diffraction, temperature programmed reduction with hydrogen, nitrogen adsorption and chemical analysis. The nonstoichiometric oxygen was quantified by temperature programmed reduction, and the catalytic tests showed that the La0,7Sr0,3MnO3 catalyst presented the higher performance for the reduction reaction of NO with CO. The partial substitution of lanthanum by strontium increased the NO conversion and the N2 yield.

Fotodegradación heterogénea de bisfenol A en agua con dióxido de titanio

Bisphenol A (BPA) is a monomer used in epoxy resin and polycarbonate manufacture. This molecule is considered as an endocrine disruptor that causes different diseases. The human exposition to this non biodegrable substance is increasing in the time; in particular, water is contaminated by industrial remainder flow. In this article heterogeneous photo degradation of a solution of BPA in water solution using a catalytic photo reactor with UV light and titanium dioxide (TiO2) was evaluated. High performance liquid chromatography (HPLC) was used to analyze the photo degradation of BPA solutions. The influence of titanium dioxide amount, BPA concentration, reaction temperature and the catalyst state like suspension and immobilized were also determinated. The highest elimination of BPA was 83.2%, in 240 min, beginning with 0.05 mM of BPA and 100 mg/L of TiO2 in suspension.