The possibility of using thiocyanate to determine iron(II) and/or iron(III) in water-acetone mixture has been re-examined as part of a systematic and comparative study involving metallic complexes of pseudohalide ligands. Some parameters that affect the complete oxidation of the ferrous cations, their subsequent complexation and the system stability have been studied to optimize the experimental conditions. Our results show the viability and potentiality of this simply methodology as an alternative analytical procedure to determine iron cations with high sensitivity, precision and accuracy. Studies on the calibration, stability, precision, and effect of various different ions have been carried out by using absorbance values measured at 480 nm. The analytical curve for the total iron determination obeys Beer's law (r = 0.9993), showing a higher sensitivity (molar absorptivity of 2.10x10(4) L cm-1 mol-1) when compared with other traditional systems (ligands) or even with the "similar" azide ion [1.53x10(4) L cm-1 mol-1, for iron-III/azide complexes, in 70% (v/v) tetrahydrofuran/water, at 396 nm]. Under such optimized experimental conditions, it is possible to determine iron in the concentration range from 0.5 to 2 ppm (15-65% T for older equipments, quartz cells of 1.00 cm). Analytical applications have been tested for some different materials (iron ores), also including pharmaceutical products for anemia, and results were compared with atomic absorption determinations. Very good agreement was obtained with these two different techniques, showing the potential of the present experimental conditions for the total iron spectrophotometric determinations (errors < 5%). The possibility of iron speciation was made evident by using another specific and auxiliary method for iron(II) or (III).
ResumoO cenário atual da Universidade de São Paulo (USP) tem, isoladamente, diversas ações ambientais em diferentes frentes, de acordo com a realidade de seus campi.Em 2010, a USP designou um coordenador de Gestão Ambiental junto à Reitoria. No ano seguinte, regulamentou a Política Ambiental da USP, que visa promover a sustentabilidade ambiental nos campi. Em 2012, foi criado um órgão institucional responsável pela gestão ambiental, a Superintendência de Gestão Ambiental (SGA), que tem como premissa ditar normas para questões ambientais em consonância com a política ambiental proposta. Esta superintendência formou, em 2012, um Grupo de Trabalho para cuidar das questões relativas aos resíduos gerados na USP. Tal grupo, composto por especialistas na área, sob a coordenação de um assessor de gabinete da própria SGA, priorizou desenvolver, através de processos participativos, estratégias e procedimentos para elaboração e implantação de uma Política de Gestão de Resíduos (PGRUSP). Esta Política, aos moldes de um trabalho anterior (PUSP-C, 2010), tem como proposta adequar as especificidades contidas na Política Nacional de Resíduos Sólidos, para o contexto universitário.Uma versão inicial da PGRUSP foi apresentadapara a comunidade acadêmica em um Fórum promovido pela SGA. Nesta ocasião, representantes de todas as categorias advindos dos diversos campi da USP, além de outros da comunidade externa, fizeram considerações sobre o conteúdo desta versão, que foi, então, reformulada. A PGRUSP prevê a elaboração dos planos de gerenciamento de resíduos em todas as unidades pertencentes à USP. Neste momento, o Grupo de Trabalho está elaborando diretrizes para a capacitação da comunidade acadêmica para a realização de um diagnóstico de resíduos, com intuito também de mobilizar e conscientizar sobre os ditames da PGRUSP. A partir da capacitação e da elaboração dos planos de gerenciamento de resíduos, pressupõe-se um aprendizado sobre questões práticas da gestão de resíduos. A geração de dados e de indicadores fornecerá embasamento para uma implementação contínua e eficaz da política. Para sistematização destes dados, está sendo desenvolvida uma plataforma virtual unificada. Assim, pretende-se controlar tanto os insumos utilizados como a geração, o armazenamento, os tratamentos e os descartes relacionados aos resíduos gerados em nossas Unidades. Pretende-se, ainda, com esta sistematização, fornecer informações que permitam à SGA atomar medidas norteadoras para melhora na gestão dos resíduos nos campi, e,consequentemente, minimizar impactos ambientais causados em todos os níveis e atividades. Palavras-chave: Instituição Ensino Superior (IES), Gestão de Resíduos, Gestão Ambiental AbstractThe actual scenario of the University of São Paulo (USP) has, in an isolated form, various environmental initiatives in diverse fronts, according to the reality of its campi.
Purpose The purpose of this paper is to propose a process management framework for Chemical Waste Treatment Laboratories (CWTL) that can be used as a management tool to identify and manage critical process. Design/methodology/approach Proposition of a generic classification for categories of chemical waste; use of the ABC analysis as a tool for analysis of priority in relation to the inputs of an CWTL; use of the process matrix (variety vs volume) to identify the key resources required to perform the activities of a CWTL; and use of mapping process techniques to map the processes defined and calculate times. Findings The proposed framework was applied to a CWTL at University of São Paulo, Brazil, and showed that the high variability of demand is a significant factor in the management of this laboratory, requiring processes that are flexible to meet this demand. The results showed that the applicability of the production and operations management theories within the scope of process management of CWTLs, proved to be useful tools for improving the treatment efficiency of chemical waste in these facilities. Originality/value The novelty of this work is in the fact of using production and operations management tools in the management of CWTLs to propose diagnoses to improve the management of their processes. The proposition of a comprehensive classification for chemical wastes generated in CWTLs is also highlighted.
A sensitive and alternative method for the spectrophotometric determination ofchromium(III) based on the formation of chromium(III)/azide complexes was established byinvestigating a new band in the ultraviolet region. The best experimental conditions for the analyticaldetermination of this metallic ion were: ligand and perchloric acid analytical concentration = 493 and12.0 mmol L -1 , respectively; aqueous medium; T = 25.0 oC; contact time = 1 hour. The maximummolar absorptivity coefficient occurred at 287 nm (average 1.481 ± 0.008 × 10 4 L mol -1 cm -1 ), leadingto the determination of metal ion concentrations one hundred times lower than the ones formerlydetermined in the visible region. The system obeys Beer’s Law and is suitable for chromiumdetermination in the 0.702-2.81 mg L -1 concentration range (15-65% T, 1.00 cm-width quartz cells).Analytical applications of the current method were tested with a nutritional supplement containingchromium. Results were compared with those obtained with atomic absorption spectrometry.
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