Fabiana Aparecida Lobo

Adsorption/desorption of arsenic by tropical peat: influence of organic matter, iron and aluminium

The objective of this work was to investigate the interaction of arsenic species (As(III) and As(V)) with tropical peat. Peat samples collected in Brazil were characterized using elemental analysis and 13C NMR. Adsorption experiments were performed using different concentrations of As with peat in natura and enriched with Fe or Al, at three different pH levels. Peat samples, in natura or enriched with metals, were analysed before and after adsorption processes using Fourier transform infrared spectroscopy (FTIR) spectroscopy. The adsorption kinetics was evaluated, and the data were fitted using the Langmuir and Freundlich models. The results showed that interaction between As and peat was dependent on the levels of organic matter (OM) and the metals (Fe and Al). As(III) was not adsorbed by in natura peat or Al-enriched peat, although small amounts of As(III) were adsorbed by Fe-enriched peat. Adsorption of As(V) by the different peat samples ranged from 21.3 to 52.7 μg g−1. The best fit to the results was obtained using the pseudo-second-order kinetic model, and the adsorption of As(V) could be described by the Freundlich isotherm model. The results showed that Fe-enriched peat was most effective in immobilizing As(V). FTIR analysis revealed the formation of ternary complexes involving As(V) and peat enriched with metals, suggesting that As(V) was associated with Al or Fe-OM complexes by metal bridging.

Desenvolvimento de nanocápsulas de poli-ε-caprolactona contendo o herbicida atrazina

In this study, polymeric nanocapsules of PCL containing the herbicide atrazine were prepared. In order to optimize the preparation conditions, a 23 factorial design was performed using different formulations of nanocapsules, which investigated the influence of three variables at two levels. The factors varied were the quantities of PCL, Span 60 and Myritol. The results were evaluated considering the size, polydispersity, zeta potential and association rate and the measures of these parameters were taken immediately after preparation and after 30 days of preparation. The formulations with minimum level of polymer in the preparation showed better stability results.

Sistema TS-FF-AAS com chama acetileno-ar como alternativa em relação à chama acetileno-óxido nitroso em FAAS na determinação de estanho

This work propose the development of analytical procedure for on line tin determination in analytical solutions by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) as alternative to nitrous oxide-acetylene flame by atomic absorption spectrometry, whose oxidant presents high costs with respect to air. Parameters were evaluated for the optimization of the system: flow of the carrier (air), volume of injected sample and concentration of the acid (HCl). The linear analytical curve [A= -0,00163 +0,00319 Sn], (r = 0,9998) ] was constructed on interval of 10 the 80 mg L-1 Sn. The detection limit, the relative standard deviations (n=12) and analytical frequency were: 1,7 mg L-1 Sn, £ 2,7% and 120 h-1, respectively. The TS-FF-AAS is an alternative for the determination of Sn.

Preparação de membranas de acetato de celulose organomodificadas para adsorção dos íons Cu(II), Cd(II), Mn(II) e Ni(II)

Universidade Estadual Paulista Julio de Mesquita Filho, Departamento de Engenharia Ambiental, Sorocaba, Av. Tres de Marco, 511, Alto da Boa Vista, CEP 18087180, SP, Brasil

Analytical Methodology for Determination of Trace Cu in Hydrated Alcohol Fuel

Ethyl alcohol (ethanol) is considered to be a highly viable alternative fuel. Its production from biomass means that it can provide a source of energy that is both clean and renewable. The in‐ clusion of ethanol as a component of gasoline can help to reduce problems of pollution in many regions, since it eliminates the needto use tetraethyl lead (historically notorious as a highly tox‐ ic trace component of the atmosphere in major cities) as an anti-knock additive.

Preparation and Characterization of Polymeric Microparticles Used for Controlled Release of Ametryn Herbicide

There is increasing pressure to improve agricultural productivity, due to rapid population growth, increased consumption and global demand for high quality products. As a result, agricultural chemicals have become essential for the control of weeds, pests and diseases in a wide range of crops. Ametryn (2-ethylamino-4-isopropylamino-6-methylthio-s-2,4,6triazine) is a selective herbicide belonging to the s-triazine family, whose activity is the result of inhibition of photosynthesis by blocking of electron transport. The ametryn molecule (Figure 1) contains a symmetrical hexameric aromatic ring in its chemical structure, consisting of three carbon atoms and three nitrogen atoms in alternate positions. The herbicide is classified as a methylthiotriazine, due to the presence of the SCH3 group (Tennant et al., 2001).

Analytical Methodology for the Determination of Trace Metals in Biodiesel

The demand for energy resources by various systems such as production and transportation, as well as for physical comfort continues to grow apace, intensifying global dependence on fossil fuels and their derivatives. For this reason, numerous private and public programs in several countries have established feasible alternatives for the substitution of petroleum derivatives (Sahin, 2011; Saint Pierre et al., 2003). These alternatives are aimed at reducing dependence on imported and non-renewable energy, mitigating some of the environmental impacts caused by petroleum derivatives, and developing alternative technologies in the area of energy (Oliveira et al., 2002). Biodiesel has emerged as a promising alternative to petroleum, firstly because it promotes a qualitative and quantitative reduction of the emission of various air pollutants (Agarwai, 2005; Lopez et al., 2005; Ilkilic  Behcet, 2010; Silva, 2010;) and secondly, as a strategic source of renewable energy to substitute diesel oil and other petroleum derivatives (Chaves et al., 2008; Jesus et al., 2008). Biodiesel, also known as vegetable diesel, is a fuel obtained from renewable sources, such as vegetable oils and animal fats, by means of chemical processes such as transesterification, esterification and thermal cracking (Chaves et al., 2010, Oliveira et al., 2009, Jesus et al., 2010; Arzamendi et al., 2008; Canakci et al., 1999; Meher et al., 2006). In chemical terms, biodiesel is defined as a mono-alkyl ester of long-chain fatty acids with physicochemical characteristics similar to those of mineral diesel. Because it is perfectly miscible and physicochemically similar to mineral diesel oil, biodiesel can be used pure or mixed in any proportions with other solvents in diesel cycle engines without the need for substantial or expensive adaptations (Ma  Hanna, 1999; Woods  Fryer, 2007). The literature highlights several important characteristics of biodiesel: (a) its market price is still relatively high when compared with that of conventional diesel fuel; (b) its content of sulfur and aromatic compounds is lower; (c) its average oxygen content is approximately 11%; (d) its viscosity and flashpoint are higher than those of conventional diesel; (e) it has a specific market niche directly associated with agricultural activities; and lastly, (f) in the case of biodiesel from used frying oil, it has strong environmental appeal (Nigam et al., 2011). The qualitative and quantitative reduction in the emissions of various air pollutants such as sulfur, particulate material, and particularly carbon, point to biodiesel as a promising

In situ differentiation of labile/inert metal species in Brazilian tropical rivers by means of a time-controlled batch-procedure based on TEPHA resin

The present study deals with a new analytical procedure based on a cellulose diffusion membrane and immobilised tetraethylene-pentamine-hexaacetate chelator (DM-TEPHA) for an in situ differentiation of labile and inert metal species in aquatic systems. The DM-TEPHA system was prepared by placing TEPHA chelator in pre-purified cellulose bags and in situ applied immersing the system in two Brazilian rivers to study the relative lability of metal species (Cu, Pb, Fe, Mn and Ni) as a function of the time and the quantity of exchanger, respectively. The procedure is simple and enables a new perspective for understanding the complexation, transport, stability and lability of metal species in aquatic systems rich in organic matter.