P.T.A. Santos

Characterization Optical of ZnAl2O4 Doped with Eu3+ Functionalized with Chitosan

ZnAl1.,9Eu0.1O4 nanoparticles were functionalization used of the 3-aminopropyltrimethoxysilane silane and chitosan, in 5:1 proportion of the nanoparticles to chitosan, in order to obtain hybrid materials for the development of luminescent markers. The samples were characterized by XRD, FTIR, TEM, excitation and emission. After functionalized the nanoparticles showed formation of crystalline phase of spinel and chitosan. TEM results have revealed that the samples presented before particle size less than 100 nm and after functionalization was observed that the particle size increases. Emission peak of Eu centered at 614 nm, corresponding to the transition 5D07F2. Nanoparticles before and after functionalization showed the spectral lines characteristics of Eu ion 5D07Fj where (J = 0,1,2,3,4). After functionalization the sample presented an increase of luminescence intensity.

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%.

Obtaining of Chitosan/ZNAL1,9EU0,05O4 Film for Application as Biomaterial

This work reports the development and characterization by SEM, XRD, FTIR, emission and excitation chisonan/ZnAl1.9Eu0.05O4 films with a mass proportion of 1:1. The powders were deagglomerated and passed 325 mesh screens and added to the diluted chitosan in 1% acetic acid. The materials were filtered and placed in petri dishes and placed in an oven at 60°C for solvent evaporation. After drying the film, a solution of 1M sodium hydroxide was added in order to obtain a film with neutral pH. With the XRD, it has been verified that the chitosan/ZnAl1.9Eu0.05O4 films presented the chitosan peaks and ZnAl2O4. Through the SEM, it has been observed that the chitosan/ZnAl1.9Eu0.05O4 presented a protruding surface. The results presented in emission and excitation spectra suggest that the film chitosan/ ZnAl1.9Eu0.05O4 exhibit good luminescence properties, and are promising to be applied as a luminescent marker in future applications in the field of biomaterials.

Evaluation of NiFe2O4 Spinel, Synthesized by Combustion Reaction, as a Catalyst for Selective CO Oxidation

The selective reaction of CO oxidation (PROX) was named as the most attractive way to reduce the CO concentration, thereby purifying the hydrogen. The aim of this work is to make the structural and morphologic characterization of the NiFe2O4 spinel synthesized by combustion reaction, using glycine as fuel, and to evaluate as catalyst in the reaction of selective oxidation of carbon monoxide in the presence of hydrogen, oxygen and carbon monoxide. The powder was prepared by using a vitreous silica crucible on a hot plate at 480°C and according to stoichiometry established by theory of propellants and explosive. The powder was characterized by X-ray diffraction (XRD), FTIR, textural analyses, transmission electron microscopy (TEM) and catalytic measurements. The results from XRD show characteristic peaks of spinel phase without presence of secondary phases. The morphologic results show surface area of 3.1 m2/g and particle size calculated by TEM of 21.72 nm. The catalyst was active and selective for O2, reaching 100% of conversion.

Preparation of NiFe2O4 and ZnFe2O4 Samples by Combustion Reaction and Evaluation of Performance in Reaction Water Gas Shift Reaction - WGSR

This paper aims to synthesize and characterize nanosized nickel and zinc ferrites (NiFe2O4 and ZnFe2O4) samples by a combustion reaction method, using glycine as fuel. The performance in HT-WGRS reaction the samples was investigated. The results showed that the combustion reaction was effective in the production of major phases of the spinel ferrite (crystallite sizes of 44 and 27 nm) and presence of the secondary phases, such as Ni and ZnO, with surface area 3 and 115 m2/g for NiFe2O4 and ZnFe2O4, respectively. HT-WGSR activity was achieved (80%) to NiFe2O4 ferrite in the temperature range of 300 - 500°C.

Avaliação catalítica dos espinélios ZnAl2O4 e ZnAl1,9Eu0,1O4 na transesterificação metílica do óleo de soja

Este estudo objetivou avaliar o efeito da dopagem de europio na estrutura e na morfologia do espinelio ZnAl1,9Eu0,1O4 e seu desempenho como catalisador na transesterificacao metilica do oleo de soja. Os pos do espinelio ZnAl1,9Eu0,1O4 foram sintetizados por meio da reacao de combustao e caracterizados por difracao de raios X (DRX), espectroscopia de absorcao optica na regiao do infravermelho com transformada de Fourier (FTIR), microscopia eletronica de varredura e analise termogravimetrica. As reacoes de transesterificacao foram conduzidas a 160 e 180 oC, razao molar oleo/alcool 1:15, 2% de catalisador e tempo de reacao 3 h. Os resultados das caracterizacoes por DRX e FTIR indicaram a fase espinelio do aluminato e duas bandas de absorcao entre 450 e 700 cm-1, caracteristicas da estrutura de espinelio. Os resultados das reacoes de transesterificacao mostraram que a dopagem de ZnAl2O4 com 0,1 mol de europio favoreceu um aumento na conversao catalitica de 15,8% para 68,7%, indicando que os ions europio tornam o catalisador mais ativo. Aumentando a temperatura da reacao de 120 para 180 oC promoveu um aumento consideravel na conversao catalitica de 18,4 para 68,7%, utilizando o catalisador dopado com europio. A conversao do catalisador reutilizado ZnAl1,9Eu0,1O4 mostrou uma reducao em cerca de 31% quando foi utilizado pela terceira vez.

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.

Magnetic Evaluation of Ni-Zn Ferrites Doped with Aluminium

Ni0.5Zn0.5Fe1.97Al0.3O4 ferrites were synthesized by combustion reaction method and after calcined at 700°C/1 h, with the aim to investigate how the Al3+ ions substitution byNi2+ ions can influence the magnetic properties. The results from X-ray diffraction showed the formation of a unique Ni-Zn ferrite phase with average crystallite size of 8 and 22nm, before and after calcination, respectively. The synthesize samples presented a superparamagnetic behavior, with saturation magnetization of 0.9 emu/g, and coercive field of 0.05 kOe, and after calcination the samples presented soft magnetic behavior with saturation magnetization of 40.0 emu/g and coercive field of 0.04 kOe.

Modificação da superfície do ZnAl1,9Eu0,05O4 visando a obtenção do híbrido ZnAl1,9Eu0,05O4/SiO2 para aplicação como biossensor

This study aimed to investigate the influence of surface modification of ZnAl1.9Eu0.05O4 nanoparticles for obtaining hybrid ZnAl1.9Eu0.05O4/SiO2 for application as a biosensor. Initially ZnAl1.9Eu0.05O4 nanoparticles were synthesized by combustion reaction and, subsequently, their surfaces were modified with silane agent. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and excitation and emission spectroscopy. The results showed formation of ZnAl2O4 as the major phase. By SEM, hard agglomerates, irregularly shaped in the form of plaques, with the presence of few irregular and variables pores were observed. The surface modification was confirmed by FTIR through the silanol and siloxane groups. The excitation and emission spectra revealed the presence of a broadband of ZnAl2O4 matrix, and fine and intense transitions from europium ion arising from doping of non-stoichiometric ZnAl2O4 with the europium. From the results of emission and excitation, it was observed that the luminescence of ZnAl1.9Eu0.05O4/SiO2 hybrid presented a small decrease in relation to the ZnAl1.9Eu0.05O4 nanoparticles. This decrease was almost insignificant in relation to the benefits of silanization caused by the introduction of functional groups that promote combination of hybrid ZnAl1.9Eu0.05O4/SiO2 with biomolecules, being this promising for application as a biosensor used in the biomedical field for the diagnosis and treatment of diseases.

Hybrid Films Photoluminescence of Chitosan/ZnAl2O4

This work reports the photoluminescence chitosan/ZnAl2O4 films in mass ratios 1:1, 1:2, 1:3, 1:4 and 1:5, respectively. The films were presented flexible, opaque, with a thickness of 0.04 mm and were characterized by XRD, FTIR, emission and excitation. The results show the presence of characteristic peaks of chitosan and ZnAl2O4, and bands related to the presence of chitosan, silanol and siloxane groups and silane agent used in surface modification ZnAl2O4, which acts as a binding agent with the chitosan all movie reviews. The excitation and emission spectra showed the presence of broadband processes associated with charge transfer from Al +3 the O-2 in all the films, and that the highest photoluminescence intensities were observed for the films 1:1 and 1:2, which showed higher concentrations than the concentrations Qs 1:3, 1:4 and 1:5. Thus, Qs acted as a binder, transferring energy to Al +3 the O- 2.