Intracellular biosynthesis and removal of copper nanoparticles by dead biomass of yeast isolated from the wastewater of a mine in the brazilian Amazonia

In this study was developed a natural process using a biological system for the biosynthesis of nanoparticles (NPs) and possible removal of copper from wastewater by dead biomass of the yeast Rhodotorula mucilaginosa. Dead and live biomass of Rhodotorula mucilaginosa was used to analyze the equilibrium and kinetics of copper biosorption by the yeast in function of the initial metal concentration, contact time, pH, temperature, agitation and inoculum volume. Dead biomass exhibited the highest biosorption capacity of copper, 26.2 mg g(-1), which was achieved within 60 min of contact, at pH 5.0, temperature of 30°C, and agitation speed of 150 rpm. The equilibrium data were best described by the Langmuir isotherm and Kinetic analysis indicated a pseudo-second-order model. The average size, morphology and location of NPs biosynthesized by the yeast were determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The shape of the intracellularly synthesized NPs was mainly spherical, with an average size of 10.5 nm. The X-ray photoelectron spectroscopy (XPS) analysis of the copper NPs confirmed the formation of metallic copper. The dead biomass of Rhodotorula mucilaginosa may be considered an efficiently bioprocess, being fast and low-cost to production of copper nanoparticles and also a probably nano-adsorbent of this metal ion in wastewater in bioremediation processFundação de Amparo à Pesquisa do Estado de São Paulo - FAPES

Surface-enhanced Raman spectroscopy studies of organophosphorous model molecules and pesticides

This work reports the analytical application of surface-enhanced Raman spectroscopy (SERS) in the trace analysis of organophosphorous pesticides (trichlorfon and glyphosate) and model organophosphorous compounds (dimethyl methylphosphonate and o-ethyl methylphosphonothioate) bearing different functional groups. SERS measurements were carried out using Ag nanocubes with an edge square dimension of ca. 100 nm as substrates. Density functional theory (DFT) with the B3LYP functional was used for the optimization of ground state geometries and simulation of Raman spectra of the organophosphorous compounds and their silver complexes. Adsorption geometries and marker bands were identified for each of the investigated compound. Results indicate the usefulness of SERS methodology for the sensitive analyses of organophosphorous compounds through the use of vibrational spectroscopy.FAPESPFAPESPCNPqCNPqCAPESCAPE

Biosynthesis and uptake of copper nanoparticles by dead biomass of Hypocrea lixii isolated from the metal mine in the Brazilian Amazon Region

A biological system for the biosynthesis of nanoparticles (NPs) and uptake of copper from wastewater, using dead biomass of Hypocrea lixii was analyzed and described for the first time. The equilibrium and kinetics investigation of the biosorption of copper onto dead, dried and live biomass of fungus were performed as a function of initial metal concentration, pH, temperature, agitation and inoculum volume. The high biosorption capacity was observed for dead biomass, completed within 60 min of contact, at pH 5.0, temperature of 40 °C and agitation speed of 150 rpm with a maximum copper biosorption of 19.0 mg g(-1). The equilibrium data were better described using the Langmuir isotherm and kinetic analysis indicated that copper biosorption follows a pseudo-second-order model. The average size, morphology and location of NPs biosynthesized by the fungus were determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). NPs were mainly spherical, with an average size of 24.5 nm, and were synthesized extracellularly. The X-ray diffraction (XRD) analysis confirms the presence of metallic copper particles. Infrared spectroscopy (FTIR) study revealed that the amide groups interact with the particles, which was accountable for the stability of NPs. This method further confirmed the presence of proteins as stabilizing and capping agents surrounding the copper NPs. These studies demonstrate that dead biomass of Hypocrea lixii provides an economic and technically feasible option for bioremediation of wastewater and is a potential candidate for industrial-scale production of copper NPs.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - 2010/52305-1

Vibrational analysis of coordination compounds of nickel (II): an approach to the teaching of point groups

This paper presents an IR and Raman experiment executed during the teaching of the course "Chemical Bonds" for undergraduated students of Science and Technology and Chemistry at the Federal University of ABC, in order to facilitate and encourage the teaching and learning of group theory. Some key aspects of this theory are also outlined. We believe that student learning was more significant with the introduction of this experiment, because there was an increase in the discussions level and in the performance during evaluations. This work also proposes a multidisciplinary approach to include the use of quantum chemistry tools

Interaction of SO2 with molecular and ionic species: Raman spectroscopy and theoretical calculations

No presente trabalho foram investigados vários sistemas moleculares contendo o dióxido de enxofre (SO2) como espécie elétron aceptora e diversas espécies elétron doadoras como aminas (alifáticas e aromáticas), complexos inorgânicos e líquidos iônicos. Estes compostos são chamados de complexos do tipo doador-aceptor, que no caso do SO2 são caracterizados por apresentarem baixas energias de ligação entre as espécies se comparada à maioria dos complexos desta categoria. A caracterização vibracional dos complexos e adutos de SO2, assim como do processo de transferência de carga (CT) intermolecular e da estabilidade destes sistemas consistem nos principais objetivos deste trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica (UV-Vis), espectroscopia vibracional (Raman e infravermelho), cálculos de química quântica (DFT) e cálculos de dinâmica molecular clássica (MD). No caso de complexos entre aminas e SO2 foi observado que além da basicidade das aminas, o efeito estérico consiste em um fator crucial para a estabilidade. No caso de aminas aromáticas, complexos coloridos foram formados permitindo a obtenção de espectros Raman ressonante. No caso de um complexo inorgânico, com utilidade potencial como sensor de SO2foi observada a aplicação da espectroscopia Raman ressonante na caracterização do complexo de estequiometria 2:1. Já no caso da interação de SO2 e líquidos iônicos (LI) foi observada a capacidade de absorção de SO2 por LI e a conseqüente mudança das propriedades físico-químicas destes líquidos, o que abre a possibilidade, além de sua potencial utilização no contexto ambiental, de sintonizar propriedades de líquidos iônicos através da adição controlada de SO2.In the present work molecular systems bearing the sulfur dioxide (SO2) as an electron acceptor species and several electron donor species as amines (aliphatic and aromatic), inorganic complexes and ionic liquids were investigated. Such complexes are commonly known as donor-acceptor complexes, and in particular, in the case of SO2 complexes are characterized by low binding energies when compared with the majority of charge transfer (CT) complexes. The vibrational characterization of the SO2 complexes, as well as of the intermolecular charge transfer (CT) process and of their stabilities are the main subjects of this work, and for such, electronic spectroscopy (UV-Vis), vibrational spectroscopy (Raman and infrared), quantum chemical (DFT) calculations and molecular dynamics (MD) simulations were used. In the case of complexes formed by amines and SO2 it was observed that besides the amine basicities, the steric effect plays a crucial role in their stabilities. In the case of aromatic amines, colored complexes were formed allowing the resonance Raman study. The use of Raman spectroscopy in the characterization of an inorganic complex (SO2 sensor) indicates the potential use of the resonance Raman effect for SO2 monitoring. In the case of the interaction between SO2 and ionic liquids it was observed the great capability of ionic liquids as SO2 absorbers, and the consequent change in the physical-chemical properties of these liquids, what opens the possibility, in addition to its potential use in the environmental context, for tuning the ionic liquids properties via the controlled addition of SO2

Vibrational, resonance Raman and electronic spectroscopies of nitroderivatives in conjugated systems

No presente trabalho foram investigados vários sistemas moleculares contemplando um ou mais grupos NO2 com características fortemente elétron atraentes, e por outro lado um grupo fortemente elétron doador (NH2, OH ou N3H) conectados através de um anel benzênico ou piridínico. A caracterização das propriedades de transferência de carga intramolecular (CT) nesses sistemas constitui um dos principais objetivos do trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica, espectroscopia vibracional (Raman e infravermelho) e com grande destaque, a espectroscopia Raman ressonante. Essa investigação permitiu a caracterização dos grupos cromofóricos envolvidos na CT entre os vários substituintes e suas posições relativas. Em vários casos foi possível estender a investigação para as espécies aniônicas obtidas pela desprotonação dos grupos NH2, OH e N3H, quando então se nota mudança abrupta das características da transição de transferência de carga (energia e intensidade), o que por sua vez conduz a uma muito maior deslocalização eletrônica do cromóforo, como revelado pela análise dos espectros de absorção (UV-Vis) e Raman ressonante (RR). No caso de sistemas mais estendidos, como é o caso típico do ânion do 1,3-bis(4-nitrofenil)triazeno os dados de espectroscopia eletrônica e espectroscopia Raman ressonante mostram de maneira clara a presença de duas transições de transferência de carga na região do visível, o que caracteriza um sistema bicromofórico.In the present work were investigated molecular systems bearing one or more NO2 groups, with strong electron withdrawing characteristics, in addition to a strong electron donating group (NH2, OH, N3H), connected to a benzene or pyridine ring. The characterization of the intramolecular charge transfer (CT) process in such systems is one of the main objects of this work and for such, electronic spectroscopy, vibrational spectroscopy (Raman and IR) and in special, resonance Raman spectroscopy were used. The study revealed the chromophoric moieties involved in the CT transitions in the several molecules investigated, included the ones where the relative positions of the substituents were changed. In several cases it was possible to extend the study to the anionic species that results from the deprotonation of the NH2, OH and N3H groups, where an abrupt change of the CT transition (energy and intensity) is observed, and what in its turn leads to a much more delocalized chromophore, as revealed by the UV-Vis and resonance Raman spectra. In the case of the more extended systems, as in the typical case of 1,3-bis(4-nitropheyl)triazene anion, the data show clearly the presence of two CT transitions in the visible region, what amounts to the formation of a bichromophoric system

Vibrational, resonance Raman and electronic spectroscopies of nitroderivatives in conjugated systems

No presente trabalho foram investigados vários sistemas moleculares contemplando um ou mais grupos NO2 com características fortemente elétron atraentes, e por outro lado um grupo fortemente elétron doador (NH2, OH ou N3H) conectados através de um anel benzênico ou piridínico. A caracterização das propriedades de transferência de carga intramolecular (CT) nesses sistemas constitui um dos principais objetivos do trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica, espectroscopia vibracional (Raman e infravermelho) e com grande destaque, a espectroscopia Raman ressonante. Essa investigação permitiu a caracterização dos grupos cromofóricos envolvidos na CT entre os vários substituintes e suas posições relativas. Em vários casos foi possível estender a investigação para as espécies aniônicas obtidas pela desprotonação dos grupos NH2, OH e N3H, quando então se nota mudança abrupta das características da transição de transferência de carga (energia e intensidade), o que por sua vez conduz a uma muito maior deslocalização eletrônica do cromóforo, como revelado pela análise dos espectros de absorção (UV-Vis) e Raman ressonante (RR). No caso de sistemas mais estendidos, como é o caso típico do ânion do 1,3-bis(4-nitrofenil)triazeno os dados de espectroscopia eletrônica e espectroscopia Raman ressonante mostram de maneira clara a presença de duas transições de transferência de carga na região do visível, o que caracteriza um sistema bicromofórico.In the present work were investigated molecular systems bearing one or more NO2 groups, with strong electron withdrawing characteristics, in addition to a strong electron donating group (NH2, OH, N3H), connected to a benzene or pyridine ring. The characterization of the intramolecular charge transfer (CT) process in such systems is one of the main objects of this work and for such, electronic spectroscopy, vibrational spectroscopy (Raman and IR) and in special, resonance Raman spectroscopy were used. The study revealed the chromophoric moieties involved in the CT transitions in the several molecules investigated, included the ones where the relative positions of the substituents were changed. In several cases it was possible to extend the study to the anionic species that results from the deprotonation of the NH2, OH and N3H groups, where an abrupt change of the CT transition (energy and intensity) is observed, and what in its turn leads to a much more delocalized chromophore, as revealed by the UV-Vis and resonance Raman spectra. In the case of the more extended systems, as in the typical case of 1,3-bis(4-nitropheyl)triazene anion, the data show clearly the presence of two CT transitions in the visible region, what amounts to the formation of a bichromophoric system

Estudo do comportamento cinético de oxidação do ácido mandélico por Estudo do comportamento cinético de oxidação do ácido mandélico por vanádio(V) em meio de ácido sulfúrico: efeito da presença de CTAB

O comportamento cinético da oxidação de ácido mandélico por vanádio(V) em meio de ácido sulfúrico foi investigado a 303 K. A constante de velocidade foi determinada espectrofotometricamente, por meio do aparecimento de vanádio(IV) em 760 nm. A oxidação mostrou dependência de primeira ordem com relação à concentração de vanádio(V) e ordem fracionária com relação à concentração de ácido mandélico e de ácido sulfúrico. A lei de velocidade não foi afetada na presença do surfactante catiônico brometo de cetil-trimetil-amônio. A constante de velocidade foi sistematicamente maior em meio contendo surfactante. A constante de velocidade aumentou com o aumento da força iônica e com a diminuição da constante dielétrica. Os parâmetros de ativação foram calculados a partir das constantes de velocidade de 2ª ordem, k2, para diferentes concentrações de substrato de 298 a 318K. O mecanismo de oxidação foi proposto a partir da lei de velocidade experimental.

Probing the Reorganization of Ionic Liquids’ Structure Induced by CO 2 Sorption

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Extra and intracellular synthesis of nickel oxide nanoparticles mediated by dead fungal biomass.

The use of dead biomass of the fungus Hypocrea lixii as a biological system is a new, effective and environmentally friendly bioprocess for the production and uptake of nickel oxide nanoparticles (NPs), which has become a promising field in nanobiotechnology. Dead biomass of the fungus was successfully used to convert nickel ions into nickel oxide NPs in aqueous solution. These NPs accumulated intracellularly and extracellularly on the cell wall surface through biosorption. The average size, morphology and location of the NPs were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The NPs were mainly spherical and extra and intracellular NPs had an average size of 3.8 nm and 1.25 nm, respectively. X-ray photoelectron spectroscopy analysis confirmed the formation of nickel oxide NPs. Infrared spectroscopy detected the presence of functional amide groups, which are probable involved in particle binding to the biomass. The production of the NPs by dead biomass was analyzed by determining physicochemical parameters and equilibrium concentrations. The present study opens new perspectives for the biosynthesis of nanomaterials, which could become a potential biosorbent for the removal of toxic metals from polluted sites