Desenvolvimento e caracterização de micropartículas de amido reticuladas com agente fosfatado e avaliação da adsorção do azul de metileno

Starch has properties that make it one of the most studied biopolymers today. It is biodegradable, biocompatible, stable and non-toxic. This work has synthesis of starch and tapioca microparticles, through chemical modification by crosslinking with sodium tripolyphosphate agent in concentrations 7.5 and 15% (m / m). The amylose content was measured for starch and commercial cassava starch at 21.8% and 28.6%, respectively. According to the solubility index, processing in basic medium does not change the solubility of the material, but the addition of crosslinking agent increases this index, which changed from 12.8% for the control unprocessed, to 22.4% for the A5R15 sample. Soluble starch-based materials had a significant increase in the crosslinking density by increasing the concentration of crosslinker, from 1.4 in A5R7,5 sample, to 1.9 in A5R15. The cassava starch-based materials exhibited an opposite behavior: to increase the concentration of crosslinker crosslinking density decreased significantly in F5R7.5 from 2.9, to 1.9 in F5R15 sample. The point of zero charge (PZC) shows that below pH 4 the surface is positively charged. The surface area data is between 3,04 and 1,15 m2.g-1. The pore volume between 2.94 and 1.33 cm3.g-1 and pore size around 1.5 nm. The SEM indicates uneven distribution of microparticles, which are smooth, with no ridges. The maximum adsorption capacity of the materials were tested at pH 7.7 and for A5R15 and CA sample, at pH 2, 5, 6 and 9. It is noted that the processing in basic medium reduces the adsorption capacity of CA and CF in respect fo A and F. The adsorption in A5R15 sample has great dependency on the pH, reaching a value of 587 μg.g-1 in pH 7.7. The samples A5R15 and F5R7,5 adsorbed similar amounts, according to the statistical analysis, and significantly higher than their respective controls and showed lower desorption, indicating that the modification process was effective to control the release of methylene blue. The infrared spectra not show the characteristic bands of the phosphate bonds to the material formed, however, developments in hydroxyl characteristic band suggest modification in the way this group was linked after the reaction. After adsorption, the infrared spectra show different format in the band of hydroxyl. PCA analysis shows that the greatest changes observed in the IR spectra are observed in the region of 3500 cm-1. Thermal analysis showed three thermal events related to dehydration and material degradation. It is observed that the processing increases the temperature to the first mass loss, fixed at 12%, but not observed increased stability due to the presence of crosslinker or process.

Proposta de uma matriz de decisão em energia hidrelétrica com o uso do método multicritério, para formulação de políticas públicas no estado do Paraná

Brazil is internationally acknowledged for its renewable sources, most notably, hydroelectric power plant projects which correspond to 65% of electricity production supply to the National Interconnected System. The main question behind this research is: what are the weights and the relative importance of the variables which have influence on the decision making process for the expansion of hydroelectric generation projects in Parana? The main objective is to propose a multi-criteria decision procedure, in association with water sources options that take into consideration the weight and relative importance of the alternatives having influence on the decision by enterprises in the generation of electricity in the state of Paraná. As far as the approach to the problem is concerned, this research can be classified as having mixed methodologies, applying Content Analysis, Delphi technique and the Analytic Hierarchy Process. Following Delphi methodology, a group of 21 was selected for data collection, all of those linked to Paranaense hydroelectricity market. And the main result was the construction of a decision tree in which it was possible to identify the importance and relative weight of the elements associated with the four dimensions of energy. In environmental dimension, the highest relative weight was placed on the loading capacity of Parana system; the economic dimension, the amortization of investment; in social dimension, the generation of direct work places and in institutional dimension, the availability of suitable sources of financing. Policy makers and business managers make their decisions based on specific criteria related to the organization segment, market information, economic and political behavior among other indicators that guide them in dealing with the typical tradeoffs of projects in hydropower area. The results obtained in the decision tree show that the economic bias is still the main factor in making investment decisions. However, environmental impacts on the State loading capacity, income generation, providing opportunities for direct as well as indirect jobs. And at an institutional level, the absence of funding sources show that the perception of experts is focused on other issues beyond the logic behind development per se. The order of priority of variables in this study indicates that in the current environment of uncertainty in the Brazilian economy as many variables must be analyzed and compared in order to optimize the scarce resources available to expand local development in relation to Paranaense water matrix.