Thermal infrared enthalpimetry (TIE) was used for hypochlorite determination in commercial hypochlorite-based bleaching solutions. Experimental parameters were evaluated for the reaction with a hydrogen peroxide solution. The most relevant conditions were 5% H2O2 (m/m) solution, stirring speed of 250 rpm, dispensing rate of 0.57 mL s-1, and 10 s after reaction for the simultaneous temperature readings of four replicates. Agreement to reference method NBR 9425 ranging from 98.2 to 103.2% was achieved, with a low variation among measurements (relative standard deviation < 3.5%). The number of analytical operations was reduced, and only H2O2 solution was required as a greener reagent. A low amount of residues was generated (2.4 and 152.8 mL for each replicate in TIE and official method, respectively), and the application of the green analytical procedure index (GAPI) showed the greenness of the proposed method.

The present work evaluated the effect on charge transfer in functionalized TiO2 nanostructured systems using different binders. We highlight the conditions required to form self-assembled systems by varying the number of layers, as well as by substituting them for an organic binder, cysteine. Additionally, we study the pH effect of the precursor solution (HAuCl4) on gold nanoparticles (AuNPs) formation. The morphological characterization allowed us to determine the percentage of Au atoms on the surface of the synthesized nanoparticles. Inductively coupled plasma mass spectrometry (ICP-MS) analysis determined the amount of gold deposited on the TiO2 surface, which ranged from 4.56 to 253.00 ng mm-2 depending on the system used. Based on Fourier-transform infrared spectroscopy (FTIR) and Raman analysis, it was possible to propose a photolysis mechanism for AuNP formation in accordance with the change in the binders. The different systems were subjected to hydrogen photogeneration by a water splitting process, resulting in 2.02 µmol cm-2 of hydrogen production for cysteine binder [Cys+HAuCl4-2.7]. There proved to be an excellent synergy between the morphological aspects, crystallinity, and stability of this arrangement.

A method for determining low levels of As and Cd by dispersive liquid-liquid microextraction (DLLME) and inductively coupled plasma mass spectrometry (ICP-MS) was proposed. The following parameters that affect extraction efficiency were investigated: type and volume of extraction solvent (1000 µL acetone), type and volume of dispersive solvent (75 µL carbon tetrachloride), amount of ammonium pyrrolidinedithiocarbamate and sodium diethyldithiocarbamate as chelating agents, sample mass (0.5 g in 10 mL ultrapure water), pH of sample solution (2.0) and number of washing steps (one). Accuracy was evaluated by analytes determination in sugar samples by ICP-MS after digestion by microwave-induced combustion (MIC). No significant difference was observed between results of the proposed DLLME method and MIC in the case of both analytes. Instrument calibration was performed by the standard addition method and good linearity was achieved. Limits of quantification (LOQs) were 0.7 and 0.2 ng g-1 for As and Cd, respectively. The main advantages of this method are relatively high sample mass, low dilution, suitable preconcentration factors and significantly low LOQs (ng g-1 range). When the proposed method was used for determining As and Cd in four sugar samples, their concentrations ranged from 1.13 to 2.95 ng g-1 and from 0.31 to 0.43 ng g-1, respectively.

In this work, a method using microwave-induced combustion (MIC) was optimized in order to obtain a fast, simple, efficient and greener sample preparation method for coal digestion and further determination of sulfur by inductively coupled plasma optical emission spectrometry (ICP OES). Accuracy was evaluated by comparison of the results with those obtained using elemental analysis by UV-fluorescence, microwave-assisted acid digestion with determination by ICP OES and by analysis of certified reference materials of coal. Some parameters that influence MIC method, such as the type and concentration of absorbing solution, the necessity of using a reflux step as well as the cooling time were carefully optimized. No statistical difference was observed for combustion without reflux followed by 5 min of cooling, in comparison to the reference values obtained by elemental analysis. Complete digestion was obtained with this fast and simple method (total digestion program required only 6 min) and using a diluted acid solution for quantitative recovery. The feasibility of digests for sulfur determination as sulfate by ion chromatography (IC) with conductivity detection was also demonstrated. The possibility of determining other elements, commonly monitored in coals, is another advantage of this high-efficiency digestion method (MIC) combined with the multielemental capacity of ICP OES or IC instruments.

Em termos ambientais, a expansão de áreas urbanas tornou-se um problema mais grave do que o crescimento demográfico em si. Para fazer frente a esse desafio, a Organização para a Cooperação e Desenvolvimento Econômico (OCDE) indica a necessidade de mudanças na gestão das cidades, com a adoção de estratégias participativas de intervenção como forma de reduzir os conflitos socioambientais e diminuir o efeito da poluição sobre o meio natural. Este artigo tem como pano de fundo a formulação de políticas para a ocupação de áreas de mananciais em contextos urbanos, tomando como estudo de caso a percepção da população residente e dos representantes das instituições de governo sobre a conservação de mananciais subterrâneos de formação cárstica na Região Metropolitana de Curitiba.

In environmental terms, the expansion of urban areas has become a problem that is more serious than that of population growth it self. To face this challenge, the Organization for Economic Cooperation and Development (OECD) indicates the need for changes in city management with the adoption of participative intervention as a strategy to reduce socio-environmental conflicts and control the effects of pollution on the natural environment. The background of this paper is the formulation of watershed occupation policies in urban contexts. The paper studies the perception of residents and representatives of government institutions about the conservation of karst groundwater in the Metropolitan Region of Curitiba.

A method based on pyrohydrolysis was proposed for cement sample preparation and further chloride determination by spectrophotometry using flow injection analysis. Analytical parameters were evaluated and, under the selected conditions, the calibration curve was linear in the range of 0.2 to 10.0 µg mL-1 with r2 = 0.998. The limit of detection was5 µg g-1 of chloride and the relative standard deviation was less than 7%. The proposed pyrohydrolysis method is relatively simple and can be used for sample preparation for further spectrophotometric determination of low concentrations of chloride in cement.

Currently, algae and algae products are extensively applied in the pharmaceutical, cosmetic and food industries. Algae are the main organisms that take up and store heavy metals. Therefore, the use of compounds derived from algae by the pharmaceutical industry should be closely monitored for possible contamination. The pollution generated by heavy metals released by industrial and domestic sources causes serious changes in the aquatic ecosystem, resulting in a loss of biological diversity and a magnification and bioaccumulation of toxic agents in the food chain. Since algae are at the bottom of the aquatic food chain, they are the most important vector for transfer of pollution to upper levels of the trophic chain in aquatic environments. Moreover, microalgae are also used for the bioremediation of wastewater, a process that does not produce secondary pollution, that enables efficient recycling of nutrients and that generates biomass useful for the production of bioactive compounds and biofuel.