An Analysis of the Potential Risk Exposure to Lead (Pb) through Urban Community Gardens

Community gardening in cities is increasing, driven by social interaction and food security. City soils are sinks for heavy metals; including neurotoxic lead (Pb). Exposure routes are primarily through inhalation/ingestion of soil, or second by ingestion of plants that have accumulated Pb. This research evaluates soil at three Liberty City, Florida sites estimating risk of Pb exposure through primary and secondary pathways. Soil cores were collected from Liberty City, and red Malabar spinach (Basella rubra) was grown in Pb soil treatments in a greenhouse. Total soil Pb levels and plant tissues were measured after acid digestion, by ICP-OES. In Liberty City, two sites had hotspots with areas of elevated soil Pb levels. Plants grown on Pb contaminated soil all accumulated statistically significant Pb concentrations. Therefore, there is a potential risk of Pb exposure to residents in Liberty City by exposure in hotspot sites through both the primary and secondary pathways

Investigating the binding heterogeneity of trace metal cations with SiO2 nanoparticles using full wave analysis of stripping chronopotentiometry at scanned deposition potential

Silica oxides nano- and microparticles, as well as silica-based materials, are very abundant in nature and industrial processes. Trace metal cation binding with these bulk materials is generally not considered significant in speciation studies in environmental systems. Nonetheless, this might change for nanoparticulate systems as observed in a previous study of Pb(II) with a very small SiO2 particle (7.5 nm diameter). Besides, metal binding by those nanoparticles is surprisingly characterized by a heterogeneity that increases with the decrease of metal-to-particle ratio. Therefore, it is interesting to extend this study to investigate different trace metals and the influence of the nanoparticle size on the cation binding heterogeneity. Consequently, the Cd(II), Pb(II), and Zn(II) binding by two different sized SiO2 nanoparticles (Ludox LS30 and TM40) in aqueous dispersion was studied for a range of pH and ionic strength conditions, using the combination of the electroanalytical techniques Scanned Stripping ChronoPotentiometry and Absence of Gradients and Nernstian Equilibrium Stripping. The coupling of these techniques provides the free metal concentration in the bulk (AGNES) and information of the free and complex concentration at the electrode surface for each Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). A recent mathematical treatment allows the reconstruction of a portion of the metal to ligand binding isotherm with the included heterogeneity information using the full SSCP wave analysis. In this work, we observed that the Zn(II) binding is homogeneous, Cd(II) is slightly heterogeneous, and Pb(II) is moderately heterogeneous, whereas the results obtained with the 7.5 nm diameter nanoparticle are slightly more heterogeneous than those obtained with the one of 17 nm. These findings suggest that the Zn(II) binding is electrostatic in nature, and for both Cd(II) and Pb(II), there should be a significant chemical binding contribution.FCT-ANR/AAG-MAA/0065/2012info:eu-repo/semantics/publishedVersio

Preparation of the orgamomodified cellulose acetate membranes for adsorption of the ions Cu(II), Cd(II), Mn(II) AND Ni(II)

Cellulose acetate polymeric membranes had been prepared by a procedure of two steps, combining the method of phase inversion and the technique of hydrolysis-deposition. The first step was the preparation of the membrane, and together was organomodified with tetraethylortosilicate and 3-aminopropyltrietoxysilane. Parameters that exert influence in the complexation of the metallic ion, as pH, time of complexation, metal concentration, had been studied in laboratory using tests of metal removal. The membranes had presented resistance mechanics and reactivity to cations, being able to be an alternative for the removal, daily pay-concentration or in the study of the lability of metals complexed

Preparação, caracterização e aplicação de membranas celulósicas organomodificadas no estudo da labilidade de Cu(II), Mn(II), Ni(II) e Cd(II) em sistemas aquáticos

Neste trabalho, membranas poliméricas de acetato de celulose foram preparadas pelo procedimento de inversão de fase e juntamente com filtros de papel JP41 (Jprolab- Procedência Alemã), foram organomodificados com tetraetilortosilicato (TEOS) e 3-aminopropiltrietoxisilano (3-APTS), visando o desenvolvimento de um novo procedimento analítico para especiação in-situ de metais lábeis e inertes em sistemas aquáticos. Parâmetros que exercem influência na labilidade do íon metálico, como pH, tempo de complexação, concentração e características de matéria orgânica foram estudadas em laboratório usando testes de remoção de metais. Os tempos de equilíbrio de complexação na membrana polimérica indicaram uma cinética lenta para os íons metálicos Mn(II) e Ni(II), mais rápidas para Cu(II) e Cd(II) com uma baixa recuperação de cátions metálicos. Os resultados com os testes utilizando filtros de papel organomodificados apresentaram uma cinética mais baixa para íons Cu(II) em comparação com Ni(II), Mn(II) e Cd(II). A labilidade relativa observada para cátions metálicos complexados em substâncias húmicas aquáticas (SHA) usando filtros de papel organomodificados foi Cu>>Cd>Ni>Mn. Os valores de pH, características estruturais e concentração de SHA influenciam fortemente na labilidade dos metais estudados. Os resultados obtidos mostraram que a utilização de filtros de papel organomodificados pode ser uma alternativa interessante e promissora pra a caracterização in-situ de metais lábeis/inertes em sistemas aquáticos.In this work, cellulose acetate polymeric membranes have been prepared by the procedure of phase inversion and together with paper filters JP41 (Jprolab- German origin), have been organomodified with tetraethylortosilicate (TEOS) and aminopropyltriethoxysilane (3-APTS), aiming the development of a new analytical procedure for in-situ especiation of labile and inert metallic species in aquatic systems. Parameters that exert influence on the metal lability, as pH, complexation time, concentration and characteristics of organic matter were studied in laboratory using tests of metal recovery. The equilibrium times of complexation in the polymeric membrane indicated slow kinetic for metallic ions Mn(II) and Ni(II), faster for Cu(II) and Cd(II) and a low metal removal. The results with the tests using organomodified paper filters showed lowest kinetic for ions Cu(II) in comparison with Ni(II), Mn(II) and Cd(II). The relative lability observed for metallic cations complexed in aquatic humic substances (HAS) using the paper filters was Cu>>Cd>Ni>Mn. The pH values, structural characteristics and concentration of AHS exert strong influence on the lability of studied metals. The results obtained showed that the utilization of organomodified filter papers can be an interesting and promising alternative for insitu characterization of metal lability/inertness in aquatic systems.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Controlled release of vitamin D3 using a nanocellulose-based membrane

Abstract Epidemiological studies show that a significant fraction of the global population presents low levels of vitamin D3. In order to address this problem, one way to administer the vitamin is to incorporate it in novel drug delivery systems, such as transdermal devices. A possible substance for this purpose is cellulose, which has a long history of use in the health area. However, the application of nanostructured cellulose membranes, as local drug delivery systems, remains a challenge. To develop a crystalline nanocellulose membrane as a new tool for the release of vitamin D3. A new nanostructured membrane containing nanocellulose extracted from cotton linter and vitamin D3 was produced using the “casting” technique. The membrane was characterized using high-resolution scanning electron microscopy (FEG-SEM) and Fourier transform infrared spectroscopy (FT-IR). The kinetics of vitamin release was quantified using molecular spectroscopy (UV–Vis). The FT-IR spectra showed the presence of all the active components in the membrane sample, without structural alterations or the formation of new bonds. The FEG-SEM images showed the presence of vitamin crystals on the surface and in the interior of the membrane. The release of vitamin D3 occurred in a sustained manner, obtaining 3029 IU mL−1 of vitamin D3 in 60 min. The findings demonstrated that the membrane could be used for the sustained release of vitamin D3. This new biomaterial has potential as a new model for vitamin supplementation in individuals with vitamin D3 deficiency

Scanned stripping chronopotentiometry at bismuth film rotating disc electrodes: a method for quantitative dynamic metal speciation

Environmental contextElectroanalytical methods have found wide application in trace metal speciation analysis in environmental systems. The need to find functional alternatives to mercury electrodes for in situ speciation studies has encouraged the use of bismuth as a solid-state electrode substrate. We demonstrate the utility of bismuth electrodes for quantitative dynamic speciation analysis.Bismuth film electrodes are employed for dynamic metal speciation analysis of Pb-II complexes by stripping chronopotentiometry at scanned deposition potential (SSCP). Their performance is found to be comparable to that of mercury-film electrodes. The quantitative SSCP expressions that describe the thermodynamic and kinetic complexation parameters are straightforwardly applicable to this solid electrode.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP