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Papers by Adelir Saczk

Orientadora: Shirley NakagakiCo-orientadora: Sueli Maria Drechsel, Creusa M. Macedo CostaDisserta... more Orientadora: Shirley NakagakiCo-orientadora: Sueli Maria Drechsel, Creusa M. Macedo CostaDissertação (mestrado) - Universidade Federal do ParanáResumo: Neste trabalho, primeiramente foi sintetizada a sílica gel quimicamente modificada com o grupo orgânico 3-aminopropiltrietoxissilano (3-APTS) e, em seguida, foi efetuado o estudo da imobilização da tetracarboxifenilporfirina ligada covalentemente na superfície da sílica modificada pelo grupo orgânico aminopropila em dicicloexilcarbodiimida (DCHC). A caracterização dos materiais modificados: sílica gel funcionalizada (SF-3APTS) e da porfirina imobilizada na sílica gel funcional izada (SF-TCPP) foi determinada por: análise química elementar de C, H e N, análise térmica, medidas de condutividade elétrica, método micro kjeldhal, isotermas de adsorção (área superficial específica) e espectroscopia eletrônica UV-Vis. 0 tipo de interação química envolvendo a porfirina e a superfície da sílica modificada foi investigada através da interação da sílica contendo a porfirina com solução metanólica de 4-dimetilaminopiridina (DMAP). Isto porque, o DMAP pode se ligar ao grupo amino da sílica funcionalizada liberando a porfirina em solução. Para este experimento foram preparadas duas amostras contendo a porfirina imobilizada na sílica funcionalizada: a primeira amostra foi preparada na ausência do catalisador de formação de ligação covalente, o dicicloexilcarbodiimida (DCHC) e foi caracterizado como (sólido a) e a segunda na presença do DCHC e foi caracterizado como (sólido b). As amostras foram submetidas ao tratamento com DMAP e a quantidade de porfirina removida da sílica gel funcionalizada foi determinada por espectroscopia eletrônica UVVis. Após o tratamento com DMAP observou-se que na amostra (a) menos de 5% da porfirina original ficou retida, e na amostra (b) a retenção foi superior a 52%. Estes resultados indicaram que houve uma maior interação da porfirina com o suporte modificado quando a reação se processou na presença do catalisador DCHC, indicando uma efetiva ligação covalente. A porfirina imobilizada foi metalada com íons ferro(lll) para obtenção do catalisador SF-FeTCPP. A determinação da quantidade de íons ferro presente na porfirina imobilizada foi determinada por espectroscopia de absorção atômica. A eficiência catalítica do sólido SF-FeTCPP foi estudada frente as reações de oxidação dos substratos cicloexano e cicloexeno com iodosobenzeno como agente oxidante. Os produtos foram analisados quantitativamente por cromatografia gasosa pelo método da padronização interna. Foi observada uma boa conversão para os produtos esperados nas reações de oxidação dos substratos estudados: cicloexano (cicloexanol e cicloexanona), cicloexeno (epoxicicloexano e os dois produtos alílicos cicloex-2-en-1-ol e cicloex-2-en-1-ona). As reações foram seletivas para a cicloexanona no caso do cicloexano e os produtos alílicos no caso do cicloexeno. Foi investigada também a eficiência catalítica do SF-FeTCPP frente as reações de oxidação da o-dianisidina utilizando H2O2 e PhIO como agentes oxidantes, com o intuito de verificar o potencial deste material como modelo da lignina peroxidase. As reações realizadas com o catalisador SF-FeTCPP mostraram uma boa conversão da odianisidina no seu dímero na presença de H2O2. Tais resultados, embora preliminares, indicaram a potencialidade do SF-FeTCPP como modelo para lignina peroxidase. Palavras-Chave: Citocromo P-450, ferro(lll)porfirina, catalisador suportado, reações de oxidação, porfirina, sílica gel funcionalizada, lignina peroxidase.Abstract:New supported iron (III) porphyrin-silica catalyst was prepared by covalent binding of porphyrin to silica bearing a (CH2)3NH2 group in order to study the catalytic efficiency to mimic cytochrome P450-dependent monooxygenase. The silica used was prepared by the reaction of activated silica gel and aminopropryltriethoxysilane during 24h (toluene reflux) under N2 (SF-3APTS). The catalysts were obtained from a DMF suspension of the porphyrins (TCPP - meso-tetrakis(4-carboxyphenyl) porphyrin) and the modified silica (with the organic group 3-aminopropyletoxysilane (3-APTS)) in the presence of dicyclohexilcarbodiimine catalyst (DCHC) under reflux for 4 h. The porphyrin-silica was metallated with FeCI2, then purified to remove excess of iron yielding Fe(lll)porphyrin-silica catalysts (SF-FeTCPP). The porphyrin-silica catalyst was also prepared by acetylating the unbound NH2 group (CH3COCI/pyridine/0°C) in order to avoid any secondary reactions at the level of those functions during oxidation catalysis. The catalyst solids were characterized by UV-Vis, IR, Chemical analysis, atomic absorption, thermal analysis, measurement of conductivity, micro method kjeldhal and BET adsorption isotherms (specific superficial area). The chemical bond involving the porphyrin and the surface of the modified silica was established through the reaction with 4-dimethylaminepyridine (DMAP) which competes with the porphyrin to…

Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental a... more Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental and human contamination when applied to green bell pepper crops. In this context, in this work, a reliable and sensitive method for determination of tetradifon in Brazilian green bell pepper samples involving a differential pulse voltammetry (DPV) technique on a glassy carbon electrode is proposed. The electrochemical behavior of tetradifon as followed by cyclic voltammetry (CV) suggests that its reduction occurs via an irreversible five–electron transfer vs. Ag|AgCl, KCl 3 M reference electrode. Very well–resolved diffusion controlled voltammetric peaks have been obtained in a supporting electrolyte solution composed of a mixture of 40 % dimethylformamide (DMF), 30% methanol, and 30 % NaOH 0.3 mol L−1 at −1.43, −1.57, −1.73, −1.88, and −2.05 V. The proposed DPV method has a good linear response in the 3.00 – 10.0 μmol L−1 range, with a limit of detection (L.O.D) of 0.756 μmol L−1 and 0.8...

Journal of Advances in Agriculture, 2015

In this study, the adsorption behavior of methylene blue (MB) was investigated using orange seed ... more In this study, the adsorption behavior of methylene blue (MB) was investigated using orange seed (OS) and uvaia seed (US) as low cost adsorbents. These materials were characterized using FTIR (Fourier transform infrared spectroscopy), elemental chemical analysis (CHNO), thermogravimetric analysis (TGA), zeta potential, specific surface area and a test for determination of acid sites. The parameters evaluated in the kinetic study of adsorption were contact time, initial dye concentration, mass of adsorbent and pH. The adsorption of MB onto OS and US samples could be explained by Elovich s kinetic model. The experimental isotherms data, carried out at the temperatures of 25°C, 35°C, 45°C and 55°C, were better represented by Sips. It was verified that the adsorption was spontaneous and endothermic according to the thermodynamic parameters ΔG°, ΔH ° and ΔS ° evaluated. The OS and US maximum adsorption capacity at the temperature of 25°C was 38 mg g -1 and 48 mg g -1 , respectively. The ...

Journal of Environmental Management, 2021

Electroplating sludge (ES) is a waste that is generated by the galvanization industry and is high... more Electroplating sludge (ES) is a waste that is generated by the galvanization industry and is highly toxic because it contains heavy metals. This study examined the physiochemical properties of ES residue, the recovery of the present metals, and the reuse of these metals to add value to this residue and avoid environmental contamination through its inadequate disposal. The potential for leaching of ES was investigated using various tests, and a decrease in the germination speed of Lactuca sativa seeds and the appearance of chromosomal aberrations in the cytotoxicity tests were observed. The reduction of the pH and dynamic leaching conditions favor the leaching of ES heavy metals. An increase in the ES concentration in soil decreases the speed of germination and increases the number of chromosomal aberrations that are related to aneugenic phenomena that promote tumor development. Metals were recovered through solubilization, followed by selective precipitation. The recovery of heavy metals from ES decreased its toxicity by eliminating toxic components. The reuse of the metals in the electroplating process may reduce the cost of disposal of ES, thereby rendering it an economically and environmentally friendly alternative. The products that were galvanized using the recovered solution showed the best results in the corrosion test, thereby demonstrating the viability of the use of this solution in industrial galvanization.

Microchemical Journal, 2019

A quick and simple procedure is described to determine pyridine and quinoline using voltammetric ... more A quick and simple procedure is described to determine pyridine and quinoline using voltammetric methods and carbon paste electrodes modified with activated carbon in the proportion of 50:20:30 w/w graphite:activated carbon:silicon. Studies with cyclic voltammetry indicated that reduction of organic nitrogen molecules is irreversible in ammonium chloride solution acidified to pH 2.5 with Britton-Robinson buffer. Under the best optimum conditions for the differential pulse voltammetry for pyridine and square wave voltammetry for quinoline, the analytical curve was linear from 1.0 × 10-4 to 9.0 × 10-7 mol L-1 for both analytes with limits of detection of approximately 2.0 × 10-7 mol L-1 and limits of quantification of approximately 7.0 × 10-7 mol L-1. The proposed methods were successfully applied to determine pyridine and quinoline in samples of textile effluents and fuel with minimum sample treatment.

Journal of Advances in Chemistry, Dec 11, 2014

The waste management in a university requires actions like collection, classification, segregatio... more The waste management in a university requires actions like collection, classification, segregation and treatment or final disposal for waste generated by teaching, researching and extension activities. The Chemical Waste Management Program (CWMP) of Federal University of Lavras recorded its activities during 2010 and 2011, identifying the types of collected waste according to the origin, volume and treatment, throughout the months of each year. All these data were interpreted using multivariate analysis as tool, on mode Principal Component Analysis (PCA), aiming to define strategies for the Laboratory of Chemical Waste Management (LCWM) operation logistic, responsible for the CWMP. The logistics of waste collection and treatment was defined based on departments and types of waste received, identifying the place and type of waste collected each month. Thereby, it was possible to define an operation strategy for CWMP, optimizing the chemical waste management in the academic environment.

Journal of Mechanical Engineering and Automation, 2015

The objective of this study was to adjust the kinetic data of the adsorption of residual copper(I... more The objective of this study was to adjust the kinetic data of the adsorption of residual copper(II) to the pseudo-first-order model, pseudo-second-order model, intraparticle diffusion and Elovich. The waste contained copper(II), generated in the analysis of protein determination at Departamento de Ciência dos Alimentos, of Universidade Federal de Lavras, Brazil. The concentration of copper(II) was 11.39 mg L-1 , determined by atomic absorption spectrometry, and the value found for pH was 13. Adsorption was studied employing kaolinite, advanced oxidation process (AOP) sludge and cotton lint as alternative adsorbents. Results of the percentage removal of copper(II) were compared with adsorption onto commercial activated carbon. The adsorption process was conducted at room temperature (25 ± 1°C), using 0.10 g of adsorbent and 10.0 mL of waste. The percentage removal of residual copper(II) obtained for the adsorbents active carbon, kaolinite, AOP sludge and cotton lint was 95.1, 94.5, 77.2 and 82.1%, respectively. The results showed that kaolinite was the most adequate alternative adsorbent. In this case, the final concentration of copper(II) was lower than the allowed by the Brazilian law for effluent discharge, which is 1.0 mg L-1. The adjusted results showed that the model proposed by Elovich was more adequate for removal onto active carbon and cotton lint while, for adsorption onto kaolinite and AOP sludge, the most adequate was the pseudo-second-order model.

Revista Virtual de Química, Feb 6, 2014

Um procedimento simples para a recuperacao do dicromato de potassio (K 2 Cr 2 O 7 ) a partir do t... more Um procedimento simples para a recuperacao do dicromato de potassio (K 2 Cr 2 O 7 ) a partir do tratamento da solucao residual de sulfocromica foi proposta neste trabalho por meio do processo de cristalizacao por refrigeracao. A diminuicao da temperatura favoreceu a cristalizacao do K 2 Cr 2 O 7 devido a diminuicao da solubilidade. Foram tratados 5,0 L de residuo de sulfocromica com concentracao de 48,08 g L -1 de Cr(VI) e a cristalizacao foi realizada em tres etapas ate que nao houvesse mais a formacao dos cristais. Em cada etapa foram determinadas as concentracoes de Cr total por espectrometria de absorcao atomica de chama e Cr(VI) pelo metodo espectrofotometrico com 1,5-difenilcarbazida, o que resultou na remocao de 91% e 92% de Cr total e Cr(VI), respectivamente. Apos a ultima etapa, o Cr(VI) remanescente na solucao foi reduzido a Cr(III) pela adicao de NaHSO 3 , recuperando via precipitacao em pH 8 cerca de 36,13 g de Cr(OH) 3 . O sobrenadante final foi descartado, pois as concentracoes de cromo estavam abaixo do limite maximo estabelecido pela legislacao brasileira para lancamento de efluentes, que sao de 0,10 e 1,0 mg L -1 de Cr(VI) e Cr(III), respectivamente. 628,4 g de K 2 Cr 2 O 7 foram recuperados e o sal caracterizado por difratometria de raio-X e analise termica diferencial. Foi comparada sua aplicabilidade frente ao K 2 Cr 2 O 7 padrao, na determinacao de materia orgânica em solo, na qual nao houve diferenca significativa, inferindo que o composto recuperado pode ser incorporado nas analises de rotina. Este processo de recuperacao permitiu a reutilizacao do K 2 Cr 2 O 7 , reduzindo custos com a aquisicao de novos reagentes e os impactos ambientais pelo descarte inadequado de solucoes contendo sulfocromica. DOI: 10.5935/1984-6835.20140031

Colecao Prope Digital, 2012

Journal of the Institute of Brewing, 2014

ABSTRACT There are residual organic and inorganic contaminants in the cachaça production chain. A... more ABSTRACT There are residual organic and inorganic contaminants in the cachaça production chain. Among the organic contaminants, ethyl carbamate has been widely studied. It is formed naturally during the fermentation processes and can be found in many foods and beverages such as bread, yoghurt, wine, beer and especially in fermented–distilled beverages such as whiskey, rum, vodka, grappa, cachaça and tiquira. The objective of this study was to identify and quantify ethyl carbamate during the steps of the production process and aging of cachaça in oak (Quercus sp) and amburana (Amburana cearensis) barrels. The cane used for cachaça production, as well as the process for obtaining the fermentation broth, did not affect the formation of ethyl carbamate, as it was not detected. Carbamate was detected in low concentrations, but was not quantified, in the fermentation, distillation and aging steps. Copyright © 2014 The Institute of Brewing & Distilling

Journal of the Institute of Brewing, 2014

ABSTRACT Ethyl carbamate, also known as urethane, is the ethyl ester of carbamic acid. Animal stu... more ABSTRACT Ethyl carbamate, also known as urethane, is the ethyl ester of carbamic acid. Animal studies with this compound have demonstrated its carcinogenic potential. In this study, gas chromatography coupled to mass spectrometry (GC-MS) was applied for the determination of ethyl carbamate in sugar cane spirits in the northern and southern regions of the state of Minas Gerais in Brazil. The samples were collected from distillates from small- and medium-scale stills. The concentrations determined for ethyl carbamate in the samples ranged from 23 to 980 µg L−1. All of the samples analysed from the southern region of Minas Gerais had an ethyl carbamate content below the limit set by the Brazilian legislation for ethyl carbamate of 150 µg L−1, while a number of samples from northern Minas Gerais exceeded this limit. No correlations were observed between the levels of ethyl carbamate and the alcohol content, acidity or copper concentrations in the samples. Copyright © 2014 The Institute of Brewing & Distilling

Journal of Environmental Chemical Engineering, 2014

ABSTRACT In this study, use was made of tucumã cake, in natura (TCN) and thermally treated (TCT),... more ABSTRACT In this study, use was made of tucumã cake, in natura (TCN) and thermally treated (TCT), as potential alternative adsorbents for the adsorption of cationic and anionic dyes. The effects of the parameters: contact time, adsorbent: adsorbate mass ratio, and initial concentration of dye were analyzed. The adsorption isotherms were established from optimized adsorption parameters. The best conditions for adsorption were: equilibrium time of 7 h, concentration of 25 mg L−1 and ratio of 1:200 for the methylene blue dye; and pH 6.5, concentration of 25 mg L−1 and ratio of 1:200 for the congo red dye. The adsorption process was best represented by the Dubinin–Radushkevich and Sips isotherms. The kinetics of adsorption of the dyes were best described by the pseudo-second-order kinetic and Elovich models. TCT showed the best maximum adsorption capacity (Qm) for the methylene blue dye (63.92 mg g−1).

Journal of Environmental Chemical Engineering, 2014

Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production pr... more Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production process, was used in natura (CN) and thermally treated (CT) form as a natural and low-cost adsorbent for the removal of the dyes malachite green (MG) and tropaeolin (TP). The CN and CT were characterized by elemental analysis, infrared spectroscopy (FTIR), N 2 adsorption/desorption and zeta potential. The effects of initial dye solution concentration, adsorbent mass/adsorbate volume ratio, initial pH of dye solution and contact time on MG and TP adsorption were studied using batch-type experiments a 25 C. The equilibrium adsorption was analysed by Langmuir, Freundlich, Sips, dual site Sips (DSS) and Dubinin-Radushkevich (D-R) isotherms. Kinetics data were evaluated by pseudo-first order and pseudo-second order models. The adsorption data of MG and TP dyes onto CN and CT were best fitted to the dual site Sips model. The maximum adsorption capacities were 37.10, 33.54, 18.60 and 55.98 mg g À1 for the systems MG/CN, MG/CT, TP/CN and TP/CT, respectively. Pseudo-second order gives the better correlation to predict the kinetic process. The thermodynamic aspects were analysed.

ECS Transactions, 2012

ABSTRACT Brazil An eletroanalytical method for determination of arsenic in sugar cane brandy usin... more ABSTRACT Brazil An eletroanalytical method for determination of arsenic in sugar cane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and mineral oil has been developed. The cyclic (CV) and linear sweep voltammetry modes (LSV) with cathodic stripping were employed for CNTPE containing mineral oil. The analytical curves were linear from 30.0 to 80.0 µg L -1 for LSV. The limit of detection (L.O.D.) was 10.45 μg L -1 and limit of quantification (L.O.Q.) was 34.33 μg L -1 . The developed method was applied to the determination of arsenic in tree commercial sugar cane brandy samples. The results were in good agreement with those obtained by HGAAS, showing that CNTPE containing mineral oil can be successfully employed to the simultaneous determination of arsenic in sugar cane brandy samples.

Semina: Ciências Agrárias, 2013

Objetivou-se neste trabalho caracterizar os compostos fenólicos e avaliar o efeito, em condições ... more Objetivou-se neste trabalho caracterizar os compostos fenólicos e avaliar o efeito, em condições de laboratório, do extrato metanólico do pó de folhas de mandioca sobre o desenvolvimento da lagarta-docartucho S. frugiperda e da saúva-limão Atta sexdens rubropilosa. O referido extrato, nas concentrações de 250, 500, 1000 e 1500 mg kg-1 , foi incorporado na dieta arti cial, a qual foi exposta a lagarta para avaliar características biológicas. Logo após a emergência dos insetos, outro experimento foi realizado para veri car a possível atividade subletal do extrato, para isso casais de S. frugiperda foram isolados em gaiolas e as posturas foram recolhidas para a quanti cação. O extrato de Manihot esculenta Crantz provocou redução na porcentagem de sobrevivência das lagartas, bem como no número de ovos. A seguir o mesmo extrato foi solubilizado em etanol 10% e aplicado em formigas, observou-se a mortalidade em comparação com a testemunha. Conclui-se que o extrato metanólico do pó de folhas de M. esculenta Crantz, contendo ácido gálico e catequina, apresenta-se como uma alternativa promissora ao controle de S. frugiperda e de Atta sexdens rubropilosa.

Journal of the Electrochemical Society, 2012

ABSTRACT

Journal of Analytical Chemistry, 2006

The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-def... more The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-defined waves can be seen at −1.77 and −1.60 V with the use of hanging mercury and glassy carbon electrodes. Acetaldehyde was shown to react at room temperature with the 2,4-dinitrophenylhydrazine and the product exhibited a differential pulse voltammetric peak at −0.90 V, which was

Food Chemistry, 2014

We have developed an eletroanalytical method that employs Cu 2+ solutions to determine arsenic in... more We have developed an eletroanalytical method that employs Cu 2+ solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110 lg L À1 and from 10 to 110 lg L À1 for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5 lg L À1 for mineral oil and 3.4 and 11.2 lg L À1 for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).

Energy & Fuels, 2009

The existence of organic and inorganic contaminants present in both fossil and biomass fuels and ... more The existence of organic and inorganic contaminants present in both fossil and biomass fuels and the fact that they can provide undesirable effects (environmental problems, corrosion processes, lead to storage instability, and others) implies a rigorous quality control of these fuels, although these contaminants make up a small part of the final fuel composition. Considering the rising importance of fuel ethanol in the worldwide panorama, this review aims at reporting the use of successful alternative analytical methods in the monitoring of organic and inorganic contaminants at trace levels, used to determine and to quantify these substances in fuel ethanol and also presenting all official norms for quality control of fuel ethanol employed by ABNT (Brazilian Association of Technical Norms), ASTM (American Society for Testing and Materials), and ECS (European Committee for Standardization).

Orientadora: Shirley NakagakiCo-orientadora: Sueli Maria Drechsel, Creusa M. Macedo CostaDisserta... more Orientadora: Shirley NakagakiCo-orientadora: Sueli Maria Drechsel, Creusa M. Macedo CostaDissertação (mestrado) - Universidade Federal do ParanáResumo: Neste trabalho, primeiramente foi sintetizada a sílica gel quimicamente modificada com o grupo orgânico 3-aminopropiltrietoxissilano (3-APTS) e, em seguida, foi efetuado o estudo da imobilização da tetracarboxifenilporfirina ligada covalentemente na superfície da sílica modificada pelo grupo orgânico aminopropila em dicicloexilcarbodiimida (DCHC). A caracterização dos materiais modificados: sílica gel funcionalizada (SF-3APTS) e da porfirina imobilizada na sílica gel funcional izada (SF-TCPP) foi determinada por: análise química elementar de C, H e N, análise térmica, medidas de condutividade elétrica, método micro kjeldhal, isotermas de adsorção (área superficial específica) e espectroscopia eletrônica UV-Vis. 0 tipo de interação química envolvendo a porfirina e a superfície da sílica modificada foi investigada através da interação da sílica contendo a porfirina com solução metanólica de 4-dimetilaminopiridina (DMAP). Isto porque, o DMAP pode se ligar ao grupo amino da sílica funcionalizada liberando a porfirina em solução. Para este experimento foram preparadas duas amostras contendo a porfirina imobilizada na sílica funcionalizada: a primeira amostra foi preparada na ausência do catalisador de formação de ligação covalente, o dicicloexilcarbodiimida (DCHC) e foi caracterizado como (sólido a) e a segunda na presença do DCHC e foi caracterizado como (sólido b). As amostras foram submetidas ao tratamento com DMAP e a quantidade de porfirina removida da sílica gel funcionalizada foi determinada por espectroscopia eletrônica UVVis. Após o tratamento com DMAP observou-se que na amostra (a) menos de 5% da porfirina original ficou retida, e na amostra (b) a retenção foi superior a 52%. Estes resultados indicaram que houve uma maior interação da porfirina com o suporte modificado quando a reação se processou na presença do catalisador DCHC, indicando uma efetiva ligação covalente. A porfirina imobilizada foi metalada com íons ferro(lll) para obtenção do catalisador SF-FeTCPP. A determinação da quantidade de íons ferro presente na porfirina imobilizada foi determinada por espectroscopia de absorção atômica. A eficiência catalítica do sólido SF-FeTCPP foi estudada frente as reações de oxidação dos substratos cicloexano e cicloexeno com iodosobenzeno como agente oxidante. Os produtos foram analisados quantitativamente por cromatografia gasosa pelo método da padronização interna. Foi observada uma boa conversão para os produtos esperados nas reações de oxidação dos substratos estudados: cicloexano (cicloexanol e cicloexanona), cicloexeno (epoxicicloexano e os dois produtos alílicos cicloex-2-en-1-ol e cicloex-2-en-1-ona). As reações foram seletivas para a cicloexanona no caso do cicloexano e os produtos alílicos no caso do cicloexeno. Foi investigada também a eficiência catalítica do SF-FeTCPP frente as reações de oxidação da o-dianisidina utilizando H2O2 e PhIO como agentes oxidantes, com o intuito de verificar o potencial deste material como modelo da lignina peroxidase. As reações realizadas com o catalisador SF-FeTCPP mostraram uma boa conversão da odianisidina no seu dímero na presença de H2O2. Tais resultados, embora preliminares, indicaram a potencialidade do SF-FeTCPP como modelo para lignina peroxidase. Palavras-Chave: Citocromo P-450, ferro(lll)porfirina, catalisador suportado, reações de oxidação, porfirina, sílica gel funcionalizada, lignina peroxidase.Abstract:New supported iron (III) porphyrin-silica catalyst was prepared by covalent binding of porphyrin to silica bearing a (CH2)3NH2 group in order to study the catalytic efficiency to mimic cytochrome P450-dependent monooxygenase. The silica used was prepared by the reaction of activated silica gel and aminopropryltriethoxysilane during 24h (toluene reflux) under N2 (SF-3APTS). The catalysts were obtained from a DMF suspension of the porphyrins (TCPP - meso-tetrakis(4-carboxyphenyl) porphyrin) and the modified silica (with the organic group 3-aminopropyletoxysilane (3-APTS)) in the presence of dicyclohexilcarbodiimine catalyst (DCHC) under reflux for 4 h. The porphyrin-silica was metallated with FeCI2, then purified to remove excess of iron yielding Fe(lll)porphyrin-silica catalysts (SF-FeTCPP). The porphyrin-silica catalyst was also prepared by acetylating the unbound NH2 group (CH3COCI/pyridine/0°C) in order to avoid any secondary reactions at the level of those functions during oxidation catalysis. The catalyst solids were characterized by UV-Vis, IR, Chemical analysis, atomic absorption, thermal analysis, measurement of conductivity, micro method kjeldhal and BET adsorption isotherms (specific superficial area). The chemical bond involving the porphyrin and the surface of the modified silica was established through the reaction with 4-dimethylaminepyridine (DMAP) which competes with the porphyrin to…

Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental a... more Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental and human contamination when applied to green bell pepper crops. In this context, in this work, a reliable and sensitive method for determination of tetradifon in Brazilian green bell pepper samples involving a differential pulse voltammetry (DPV) technique on a glassy carbon electrode is proposed. The electrochemical behavior of tetradifon as followed by cyclic voltammetry (CV) suggests that its reduction occurs via an irreversible five–electron transfer vs. Ag|AgCl, KCl 3 M reference electrode. Very well–resolved diffusion controlled voltammetric peaks have been obtained in a supporting electrolyte solution composed of a mixture of 40 % dimethylformamide (DMF), 30% methanol, and 30 % NaOH 0.3 mol L−1 at −1.43, −1.57, −1.73, −1.88, and −2.05 V. The proposed DPV method has a good linear response in the 3.00 – 10.0 μmol L−1 range, with a limit of detection (L.O.D) of 0.756 μmol L−1 and 0.8...

Journal of Advances in Agriculture, 2015

In this study, the adsorption behavior of methylene blue (MB) was investigated using orange seed ... more In this study, the adsorption behavior of methylene blue (MB) was investigated using orange seed (OS) and uvaia seed (US) as low cost adsorbents. These materials were characterized using FTIR (Fourier transform infrared spectroscopy), elemental chemical analysis (CHNO), thermogravimetric analysis (TGA), zeta potential, specific surface area and a test for determination of acid sites. The parameters evaluated in the kinetic study of adsorption were contact time, initial dye concentration, mass of adsorbent and pH. The adsorption of MB onto OS and US samples could be explained by Elovich s kinetic model. The experimental isotherms data, carried out at the temperatures of 25°C, 35°C, 45°C and 55°C, were better represented by Sips. It was verified that the adsorption was spontaneous and endothermic according to the thermodynamic parameters ΔG°, ΔH ° and ΔS ° evaluated. The OS and US maximum adsorption capacity at the temperature of 25°C was 38 mg g -1 and 48 mg g -1 , respectively. The ...

Journal of Environmental Management, 2021

Electroplating sludge (ES) is a waste that is generated by the galvanization industry and is high... more Electroplating sludge (ES) is a waste that is generated by the galvanization industry and is highly toxic because it contains heavy metals. This study examined the physiochemical properties of ES residue, the recovery of the present metals, and the reuse of these metals to add value to this residue and avoid environmental contamination through its inadequate disposal. The potential for leaching of ES was investigated using various tests, and a decrease in the germination speed of Lactuca sativa seeds and the appearance of chromosomal aberrations in the cytotoxicity tests were observed. The reduction of the pH and dynamic leaching conditions favor the leaching of ES heavy metals. An increase in the ES concentration in soil decreases the speed of germination and increases the number of chromosomal aberrations that are related to aneugenic phenomena that promote tumor development. Metals were recovered through solubilization, followed by selective precipitation. The recovery of heavy metals from ES decreased its toxicity by eliminating toxic components. The reuse of the metals in the electroplating process may reduce the cost of disposal of ES, thereby rendering it an economically and environmentally friendly alternative. The products that were galvanized using the recovered solution showed the best results in the corrosion test, thereby demonstrating the viability of the use of this solution in industrial galvanization.

Microchemical Journal, 2019

A quick and simple procedure is described to determine pyridine and quinoline using voltammetric ... more A quick and simple procedure is described to determine pyridine and quinoline using voltammetric methods and carbon paste electrodes modified with activated carbon in the proportion of 50:20:30 w/w graphite:activated carbon:silicon. Studies with cyclic voltammetry indicated that reduction of organic nitrogen molecules is irreversible in ammonium chloride solution acidified to pH 2.5 with Britton-Robinson buffer. Under the best optimum conditions for the differential pulse voltammetry for pyridine and square wave voltammetry for quinoline, the analytical curve was linear from 1.0 × 10-4 to 9.0 × 10-7 mol L-1 for both analytes with limits of detection of approximately 2.0 × 10-7 mol L-1 and limits of quantification of approximately 7.0 × 10-7 mol L-1. The proposed methods were successfully applied to determine pyridine and quinoline in samples of textile effluents and fuel with minimum sample treatment.

Journal of Advances in Chemistry, Dec 11, 2014

The waste management in a university requires actions like collection, classification, segregatio... more The waste management in a university requires actions like collection, classification, segregation and treatment or final disposal for waste generated by teaching, researching and extension activities. The Chemical Waste Management Program (CWMP) of Federal University of Lavras recorded its activities during 2010 and 2011, identifying the types of collected waste according to the origin, volume and treatment, throughout the months of each year. All these data were interpreted using multivariate analysis as tool, on mode Principal Component Analysis (PCA), aiming to define strategies for the Laboratory of Chemical Waste Management (LCWM) operation logistic, responsible for the CWMP. The logistics of waste collection and treatment was defined based on departments and types of waste received, identifying the place and type of waste collected each month. Thereby, it was possible to define an operation strategy for CWMP, optimizing the chemical waste management in the academic environment.

Journal of Mechanical Engineering and Automation, 2015

The objective of this study was to adjust the kinetic data of the adsorption of residual copper(I... more The objective of this study was to adjust the kinetic data of the adsorption of residual copper(II) to the pseudo-first-order model, pseudo-second-order model, intraparticle diffusion and Elovich. The waste contained copper(II), generated in the analysis of protein determination at Departamento de Ciência dos Alimentos, of Universidade Federal de Lavras, Brazil. The concentration of copper(II) was 11.39 mg L-1 , determined by atomic absorption spectrometry, and the value found for pH was 13. Adsorption was studied employing kaolinite, advanced oxidation process (AOP) sludge and cotton lint as alternative adsorbents. Results of the percentage removal of copper(II) were compared with adsorption onto commercial activated carbon. The adsorption process was conducted at room temperature (25 ± 1°C), using 0.10 g of adsorbent and 10.0 mL of waste. The percentage removal of residual copper(II) obtained for the adsorbents active carbon, kaolinite, AOP sludge and cotton lint was 95.1, 94.5, 77.2 and 82.1%, respectively. The results showed that kaolinite was the most adequate alternative adsorbent. In this case, the final concentration of copper(II) was lower than the allowed by the Brazilian law for effluent discharge, which is 1.0 mg L-1. The adjusted results showed that the model proposed by Elovich was more adequate for removal onto active carbon and cotton lint while, for adsorption onto kaolinite and AOP sludge, the most adequate was the pseudo-second-order model.

Revista Virtual de Química, Feb 6, 2014

Um procedimento simples para a recuperacao do dicromato de potassio (K 2 Cr 2 O 7 ) a partir do t... more Um procedimento simples para a recuperacao do dicromato de potassio (K 2 Cr 2 O 7 ) a partir do tratamento da solucao residual de sulfocromica foi proposta neste trabalho por meio do processo de cristalizacao por refrigeracao. A diminuicao da temperatura favoreceu a cristalizacao do K 2 Cr 2 O 7 devido a diminuicao da solubilidade. Foram tratados 5,0 L de residuo de sulfocromica com concentracao de 48,08 g L -1 de Cr(VI) e a cristalizacao foi realizada em tres etapas ate que nao houvesse mais a formacao dos cristais. Em cada etapa foram determinadas as concentracoes de Cr total por espectrometria de absorcao atomica de chama e Cr(VI) pelo metodo espectrofotometrico com 1,5-difenilcarbazida, o que resultou na remocao de 91% e 92% de Cr total e Cr(VI), respectivamente. Apos a ultima etapa, o Cr(VI) remanescente na solucao foi reduzido a Cr(III) pela adicao de NaHSO 3 , recuperando via precipitacao em pH 8 cerca de 36,13 g de Cr(OH) 3 . O sobrenadante final foi descartado, pois as concentracoes de cromo estavam abaixo do limite maximo estabelecido pela legislacao brasileira para lancamento de efluentes, que sao de 0,10 e 1,0 mg L -1 de Cr(VI) e Cr(III), respectivamente. 628,4 g de K 2 Cr 2 O 7 foram recuperados e o sal caracterizado por difratometria de raio-X e analise termica diferencial. Foi comparada sua aplicabilidade frente ao K 2 Cr 2 O 7 padrao, na determinacao de materia orgânica em solo, na qual nao houve diferenca significativa, inferindo que o composto recuperado pode ser incorporado nas analises de rotina. Este processo de recuperacao permitiu a reutilizacao do K 2 Cr 2 O 7 , reduzindo custos com a aquisicao de novos reagentes e os impactos ambientais pelo descarte inadequado de solucoes contendo sulfocromica. DOI: 10.5935/1984-6835.20140031

Colecao Prope Digital, 2012

Journal of the Institute of Brewing, 2014

ABSTRACT There are residual organic and inorganic contaminants in the cachaça production chain. A... more ABSTRACT There are residual organic and inorganic contaminants in the cachaça production chain. Among the organic contaminants, ethyl carbamate has been widely studied. It is formed naturally during the fermentation processes and can be found in many foods and beverages such as bread, yoghurt, wine, beer and especially in fermented–distilled beverages such as whiskey, rum, vodka, grappa, cachaça and tiquira. The objective of this study was to identify and quantify ethyl carbamate during the steps of the production process and aging of cachaça in oak (Quercus sp) and amburana (Amburana cearensis) barrels. The cane used for cachaça production, as well as the process for obtaining the fermentation broth, did not affect the formation of ethyl carbamate, as it was not detected. Carbamate was detected in low concentrations, but was not quantified, in the fermentation, distillation and aging steps. Copyright © 2014 The Institute of Brewing & Distilling

Journal of the Institute of Brewing, 2014

ABSTRACT Ethyl carbamate, also known as urethane, is the ethyl ester of carbamic acid. Animal stu... more ABSTRACT Ethyl carbamate, also known as urethane, is the ethyl ester of carbamic acid. Animal studies with this compound have demonstrated its carcinogenic potential. In this study, gas chromatography coupled to mass spectrometry (GC-MS) was applied for the determination of ethyl carbamate in sugar cane spirits in the northern and southern regions of the state of Minas Gerais in Brazil. The samples were collected from distillates from small- and medium-scale stills. The concentrations determined for ethyl carbamate in the samples ranged from 23 to 980 µg L−1. All of the samples analysed from the southern region of Minas Gerais had an ethyl carbamate content below the limit set by the Brazilian legislation for ethyl carbamate of 150 µg L−1, while a number of samples from northern Minas Gerais exceeded this limit. No correlations were observed between the levels of ethyl carbamate and the alcohol content, acidity or copper concentrations in the samples. Copyright © 2014 The Institute of Brewing & Distilling

Journal of Environmental Chemical Engineering, 2014

ABSTRACT In this study, use was made of tucumã cake, in natura (TCN) and thermally treated (TCT),... more ABSTRACT In this study, use was made of tucumã cake, in natura (TCN) and thermally treated (TCT), as potential alternative adsorbents for the adsorption of cationic and anionic dyes. The effects of the parameters: contact time, adsorbent: adsorbate mass ratio, and initial concentration of dye were analyzed. The adsorption isotherms were established from optimized adsorption parameters. The best conditions for adsorption were: equilibrium time of 7 h, concentration of 25 mg L−1 and ratio of 1:200 for the methylene blue dye; and pH 6.5, concentration of 25 mg L−1 and ratio of 1:200 for the congo red dye. The adsorption process was best represented by the Dubinin–Radushkevich and Sips isotherms. The kinetics of adsorption of the dyes were best described by the pseudo-second-order kinetic and Elovich models. TCT showed the best maximum adsorption capacity (Qm) for the methylene blue dye (63.92 mg g−1).

Journal of Environmental Chemical Engineering, 2014

Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production pr... more Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production process, was used in natura (CN) and thermally treated (CT) form as a natural and low-cost adsorbent for the removal of the dyes malachite green (MG) and tropaeolin (TP). The CN and CT were characterized by elemental analysis, infrared spectroscopy (FTIR), N 2 adsorption/desorption and zeta potential. The effects of initial dye solution concentration, adsorbent mass/adsorbate volume ratio, initial pH of dye solution and contact time on MG and TP adsorption were studied using batch-type experiments a 25 C. The equilibrium adsorption was analysed by Langmuir, Freundlich, Sips, dual site Sips (DSS) and Dubinin-Radushkevich (D-R) isotherms. Kinetics data were evaluated by pseudo-first order and pseudo-second order models. The adsorption data of MG and TP dyes onto CN and CT were best fitted to the dual site Sips model. The maximum adsorption capacities were 37.10, 33.54, 18.60 and 55.98 mg g À1 for the systems MG/CN, MG/CT, TP/CN and TP/CT, respectively. Pseudo-second order gives the better correlation to predict the kinetic process. The thermodynamic aspects were analysed.

ECS Transactions, 2012

ABSTRACT Brazil An eletroanalytical method for determination of arsenic in sugar cane brandy usin... more ABSTRACT Brazil An eletroanalytical method for determination of arsenic in sugar cane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and mineral oil has been developed. The cyclic (CV) and linear sweep voltammetry modes (LSV) with cathodic stripping were employed for CNTPE containing mineral oil. The analytical curves were linear from 30.0 to 80.0 µg L -1 for LSV. The limit of detection (L.O.D.) was 10.45 μg L -1 and limit of quantification (L.O.Q.) was 34.33 μg L -1 . The developed method was applied to the determination of arsenic in tree commercial sugar cane brandy samples. The results were in good agreement with those obtained by HGAAS, showing that CNTPE containing mineral oil can be successfully employed to the simultaneous determination of arsenic in sugar cane brandy samples.

Semina: Ciências Agrárias, 2013

Objetivou-se neste trabalho caracterizar os compostos fenólicos e avaliar o efeito, em condições ... more Objetivou-se neste trabalho caracterizar os compostos fenólicos e avaliar o efeito, em condições de laboratório, do extrato metanólico do pó de folhas de mandioca sobre o desenvolvimento da lagarta-docartucho S. frugiperda e da saúva-limão Atta sexdens rubropilosa. O referido extrato, nas concentrações de 250, 500, 1000 e 1500 mg kg-1 , foi incorporado na dieta arti cial, a qual foi exposta a lagarta para avaliar características biológicas. Logo após a emergência dos insetos, outro experimento foi realizado para veri car a possível atividade subletal do extrato, para isso casais de S. frugiperda foram isolados em gaiolas e as posturas foram recolhidas para a quanti cação. O extrato de Manihot esculenta Crantz provocou redução na porcentagem de sobrevivência das lagartas, bem como no número de ovos. A seguir o mesmo extrato foi solubilizado em etanol 10% e aplicado em formigas, observou-se a mortalidade em comparação com a testemunha. Conclui-se que o extrato metanólico do pó de folhas de M. esculenta Crantz, contendo ácido gálico e catequina, apresenta-se como uma alternativa promissora ao controle de S. frugiperda e de Atta sexdens rubropilosa.

Journal of the Electrochemical Society, 2012

ABSTRACT

Journal of Analytical Chemistry, 2006

The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-def... more The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-defined waves can be seen at −1.77 and −1.60 V with the use of hanging mercury and glassy carbon electrodes. Acetaldehyde was shown to react at room temperature with the 2,4-dinitrophenylhydrazine and the product exhibited a differential pulse voltammetric peak at −0.90 V, which was

Food Chemistry, 2014

We have developed an eletroanalytical method that employs Cu 2+ solutions to determine arsenic in... more We have developed an eletroanalytical method that employs Cu 2+ solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110 lg L À1 and from 10 to 110 lg L À1 for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5 lg L À1 for mineral oil and 3.4 and 11.2 lg L À1 for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).

Energy & Fuels, 2009

The existence of organic and inorganic contaminants present in both fossil and biomass fuels and ... more The existence of organic and inorganic contaminants present in both fossil and biomass fuels and the fact that they can provide undesirable effects (environmental problems, corrosion processes, lead to storage instability, and others) implies a rigorous quality control of these fuels, although these contaminants make up a small part of the final fuel composition. Considering the rising importance of fuel ethanol in the worldwide panorama, this review aims at reporting the use of successful alternative analytical methods in the monitoring of organic and inorganic contaminants at trace levels, used to determine and to quantify these substances in fuel ethanol and also presenting all official norms for quality control of fuel ethanol employed by ABNT (Brazilian Association of Technical Norms), ASTM (American Society for Testing and Materials), and ECS (European Committee for Standardization).