Joelda Dantas

Use of Ni-Zn ferrites doped with Cu as catalyst in the transesterification of soybean oil to methyl esters

The purpose of this work is to evaluate the performance of Ni0.5Zn0.5Fe2O4 ferrite doped with 0.1 and 0.4 mol of Cu as a catalyst for the transesterification of soybean oil to biodiesel, using methanol. The samples were characterized by X-ray diffraction, nitrogen adsorption and scanning electron microscopy. The reaction was performed for 2 hours at a temperature of 160 °C, using 10 g of soybean oil, a molar ratio of oil: alcohol of 1:20, and 4% (w/w) of catalyst. The product of the reaction was characterized by gas chromatography, which confirmed conversion to methyl esters. The diffraction patterns showed the presence only of Ni0.5Zn0.5Fe2O4 ferrite phase with a crystallite size of 29 nm. The samples doped with 0.1 and 0.4 mol of Cu showed a surface area and particle size of 22.17 m2g - 1 and 50.47 nm; and 23.49 m2g - 1 and 47.64 nm, respectively. The morphology of both samples consisted of brittle block-shaped agglomerates with a wide particle size distribution. A comparative analysis of the two catalysts indicated that the catalyst doped with 0.4 mol of Cu showed the better performance, with a conversion rate of 50.25%, while the catalyst doped with 0.1 mol of Cu showed 42.71% conversion.

Evaluation of Catalyst Ni0.4Cu0.1Zn0.5Fe2O4 on Methyl Esterification of Free Fatty Acid Present in Cottonseed Oil

This study aimed to assess the performance of the solid catalyst Ni0.4Cu0.1Zn0.5Fe2O4, synthesized by combustion reaction, over the methyl esterification reaction of the fatty acids present in cottonseed oil. The catalyst was characterized by XRD, FTIR pyridine absorption, Raman spectroscopy, and SEM. The reactions were conducted at 140 and 180°C with molar ratios of 1:3, 1:6 and 1:9, with 2% of catalyst and reaction time of 2 h. The XRD results showed that the single phase ferrite was obtained with surface area of 87 m2/g and with mesoporous characteristic. It was observed from the FTIR pyridine absorption only the presence of Lewis acid sites. The Raman spectra confirm the presence of the inverse spinel phase. The results indicated that at 180°C and molar ratio of 1:9, the conversion of free fatty acids was about 87%.

Evaluation of the Processing Conditions in the Transesterification for Biodiesel Production Using the Nanomagnetic Catalyst Ni0.5Zn0.5Fe2O4

Magnetic catalysts are easily removed from the reaction process, thereby reducing the wastewater generation. Therefore, the study proposes to evaluate the performance of the nanomagnetic catalyst Ni0.5Zn0.5Fe2O4 in the transesterification reaction of the soybean oil to produce biodiesel, varying processing conditions (temperature, molar ratio of oil:alcohol and catalyst amount) on the catalytic reaction. The catalyst was synthesized by combustion reaction and characterized by XRD, BET, magnetic measurements and gas chromatography. The results revealed the inverse spinel phase formation, type B(AB)2O4, with isotherm profile classified as type V with hysteresis loop of type 3 (H3), and surface area of 48.39 m2g-1. The magnetic hysteresis curve showed a characteristic behavior of soft magnetic material with saturation magnetization value of 55 emu/g. Chromatographic analysis confirmed that the magnetic nanoparticles are catalytically active and that the processing conditions directly influence the conversion into esters.

Synthesis of the Magnetic Nanoferrites of Spinel Type and Use in Esterification Reaction for Biodiesel Obtaining

Nanotechnology has been important in improving of the properties of the materials used in the manufacture of magnetic devices, electromagnetic radiation absorbers, cell telephony, pigments and lately in catalysis in transesterification and esterification reactions to biodiesel obtaining. The objective of this work was to synthesize and characterize magnetic materials of spinel type compound of CuFe2O4, CoFe2O4, MnFe2O4, NiFe2O4 and FeFe2O4 and to check the catalytic effect on the methyl esterification reaction of soybean oil. The samples were obtained by combustion reaction and characterized by XRD, FTIR, BET and SEM. The results analysis revealed for nanoferrites the spinel phase formation and higher specific area to the sample CoFe2O4. Generally the samples presented in irregular agglomerates form. All samples were catalytically active in the esterification reaction, with the highest conversion obtained by the sample MnFe2O4 with 57%.

Study of Nanoferrites Ni0,5Zn0,5Fe2O4 and Ni0,1Cu0,4Zn0,5Fe2O4 as Catalysts in the Methyl Transesterification of Soybean Oil

Research with emphasis on substitution of energy sources used in worldwide for renewable energy undoubtedly indicates that the use of biodiesel would be an option to increase the income in rural areas, reduction in oil derivatives spending and also new opportunities for job creation. Soon, in purpose to contribute with the research growth, this research proposes to evaluate the new catalysts performance as nanoferrites Ni0,5Zn0,5Fe2O4 (pure) and Ni0,1Cu0,4Zn0,5Fe2O4 (doped with 0.4 mol of Cu2+) in transesterification reactions of soybean oil methyl. For both samples were synthesized by chemical method in the stoichiometry of the combustion reaction, using urea as a fuel source and a resistance heating coil. During synthesis were measured time and combustion temperature. Later they were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), textural analysis (BET) and subjected to catalytic tests bench. The reaction conditions used in the transesterification were: 10 g of oil, 2 h reaction time, molar ratio of 1:20 oil and alcohol, 4% (w/w) of catalyst and reaction temperature of 160°C. Finally, the reaction product was characterized for conversion into methyl esters by gas chromatography. Results has shown only the presence of the inverse spinel phase, characteristic of Ni-Zn ferrite for both samples, with crystallite size of 26 and 29 nm, respectively. The thermogravimetric analysis has shown that samples are thermally stable, with a weight loss of 4.9 and 3.7%, respectively. The surface area and particle size were 48.89 m2g-1 and 23 nm, and 18.06 m2g-1 and 62 nm, respectively. The conversion results obtained by the transesterification reaction were 13 and 50% Ni0,5Zn0,5Fe2O4 and Ni0,1Cu0,4Zn0,5Fe2O4, respectively, indicating that sample with presence of copper was 26% more effectively, thus being one promising catalyst for the transesterification reaction, which aims to obtain biodiesel.

Synthesis, Characterization and Catalytic Performance of Nanoferrites Subjected to the Esterification Reaction

Ni0.5Zn0.5Fe2O4, Mn0.5Zn0.5Fe2O4 and Ni0.2Cu0.3Zn0.5Fe2O4 nanoferrites were synthesized, characterized and evaluated in terms of their performance as catalysts in the methyl esterification reaction of soybean oil. The nanoferrites were synthesized by combustion and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The XRD patterns show the presence of inverse spinel B(AB)2O4 phase. The EDX results confirmed the stoichiometry of the nanoferrite systems, whose morphology consisted of large block-like agglomerates with a brittle aspect and a wide agglomerate size distribution. The results indicate that the Ni0.5Zn0.5Fe2O4 nanoferrite was the most active catalyst in the esterification reaction, with conversion rates ranging from 40 to 91%.

Nanoferrites Ni-Zn Silanized with 3-Aminopropyltrimethoxysilane Using the Reflux Method

In this paper we propose nanoferrites Ni-Zn silanization with 3-aminopropyltrimethoxysilane using the method of reflux and evaluate the effect of silanization on the structure, morphology and magnetism of the magnetic nanoparticles aimed at biological applications. The samples as synthesized and after silanization were characterized by XRD, FTIR, SEM and testing magnetic attraction. The results indicated a single phase inverse spinel Ni-Zn ferrite, high intensity of diffraction peaks and a high basal width of all reflections observed, indicating that the samples are crystalline, and formation of nanoparticles. Morphologically, for nanoferrites Ni-Zn synthesized observed formation of large agglomerates in the form of spongy blocks of frail and after silanization was observed with respect dense pellets, indicating that most particles were rigidly connected by the presence of the agent silane. The characteristic bands of the spinel were observed for the Ni-Zn nanoferrites before and after silanization, and also observed the characteristic bands of silane in confirming the ferrites silanized functionalization of ferrites with the silane agent. Nanoparticles ferrite as synthesized and after silanized were strongly attracted by the presence of a magnet, immediately after the presence thereof indicating that the silane is effective is not interfere with the magnetic particles, maintaining the same magnetic behavior.

Biodiesel from Fatty Acids Found in Brazilian Native Cultures as Soybean and Cotton Using the Nanocatalyst Ni0.5Zn0.5Fe2O4

Biodiesel is a biodegradable fuel derived from renewable biomass, such as soybean and cottonseed oil, which may be obtained by different processes and requires a material to catalyze the obtaining reactions. The irons spinel comes overlapping as excellent materials to catalyze the biodiesel production reactions. Thus, the purpose of this work was the use of Ni0.5Zn0.5Fe2O4 nanoferrite as a catalyst in esterification reactions. The nanoferrite was synthesized by combustion in large scale, 200g/batch, where time and the temperature of the reactions were measured, and characterized by XRD and measuring its surface area. The biodiesel was obtained from methyl and ethyl esterification of acidified soybean oil and cottonseed, at a temperature of 160°C for 1 hour, molar ratio 1:15, 3% of catalyst and analyzed by chromatography. The nanoferrite has shown peaks of greater intensity corresponding to a majority crystal phase of the spinel and a surface area of 64.17m2/g. The conversion results for the soybean oil were 99.08% in methyl route and 98.38% in ethyl route. For cottonseed oil were 88.79% in methyl route and 78.65% in ethyl route.

Avaliação da fotoluminescência do TiO 2 sintetizado pelo método Pechini

Titanium dioxide (TiO2) stands out for use in various applications mainly due to its properties of thermal and chemical stability and its excellent optical properties. However, these properties are dependent on the type and phase morphology, which is related to the TiO2 processing method. Thus, this paper proposed to synthesize TiO2 nanoparticles by polymeric precursor method with different polymorphs, and evaluate the influence of these phases in the photoluminescent properties. For this, the stoichiometric molar proportions of citric acid:metallic cations of 1:1, 2:1, 3:1, 4:1 and 5:1 were investigated. The nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy, textural analysis, scanning electron microscopy (SEM), excitation and emission spectroscopy and determination of the band gap by UV-Vis diffuse reflectance spectroscopy. The presence of anatase and rutile was confirmed by XRD in different proportions for each sample. The agglomerate size increased with the citric acid/metal cations ratio as observed by SEM. Concerning photoluminescence, the maximum intensity in the emission spectrum occurred at the wavelength of 533 nm for the 3:1 sample and the maximum intensity in the excitation spectrum occurred for the 2:1 sample at the wavelength of 451 nm.Titanium dioxide (TiO2) stands out for use in various applications mainly due to its properties of thermal and chemical stability and its excellent optical properties. However, these properties are dependent on the type and phase morphology, which is related to the TiO2 processing method. Thus, this paper proposed to synthesize TiO2 nanoparticles by polymeric precursor method with different polymorphs, and evaluate the influence of these phases in the photoluminescent properties. For this, the stoichiometric molar proportions of citric acid:metallic cations of 1:1, 2:1, 3:1, 4:1 and 5:1 were investigated. The nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy, textural analysis, scanning electron microscopy (SEM), excitation and emission spectroscopy and determination of the band gap by UV-Vis diffuse reflectance spectroscopy. The presence of anatase and rutile was confirmed by XRD in different proportions for each sample. The agglomerate size increased with the citric acid/metal cations ratio as observed by SEM. Concerning photoluminescence, the maximum intensity in the emission spectrum occurred at the wavelength of 533 nm for the 3:1 sample and the maximum intensity in the excitation spectrum occurred for the 2:1 sample at the wavelength of 451 nm.

Síntese e caracterização do ferroespinélio Ni0,7Zn0,3Fe2O4: avaliação de desempenho na esterificação metílica e etílica

O ferroespinelio Ni0,7Zn0,3Fe2O4 foi sintetizado por reacao de combustao e seu desempenho catalitico na reacao de esterificacao metilica e etilica do oleo de soja foi investigado. As amostras foram caracterizadas por difracao de raios X, analise de refinamento, espectroscopia de fluorescencia de raios X por energia dispersiva, espectroscopia no infravermelho com transformada de Fourier, analise textural, microscopia eletronica de varredura, densidade por picnometria de helio, analise granulometrica, analise termogravimetrica, medidas magneticas e testes cataliticos. A sintese foi eficiente obtendo o ferroespinelio com fase unica Ni0,7Zn0,3Fe2O4, com tamanho de cristalito de 20 nm, elevada area superficial (86 m2/g) e magnetizacao de saturacao de 18 emu/g. O ferroespinelio possibilitou atividade catalitica promissora em ambas as condicoes reacionais estudadas, sendo mais ativo na conversao do oleo de soja em biodiesel na esterificacao metilica apresentando conversao media de 93,9±2,8%.