Caracterização e avaliação da atividade fotocatalítica de catalisadores baseados no TiO2, sintetizados mediante hidrólise em uma mistura de solventes

This study involved the synthesis of photocatalysts based on titanium dioxide (TiO2). The photocatalysts were synthesized by the sol-gel method using three different proportions of acetone (25%, 50% and 75% v/v) in water/acetone mixtures, in order to control the hydrolysis of the precursor of titanium (titanium tetraisopropoxide). Aiming to investigate the structural, morphological and electronic changes provoked by the use of the solvent mixtures, different methodologies were used to characterize the oxides, such as X-ray diffraction (XRD), RAMAN spectroscopy, UV-Vis diffuse reflectance spectroscopy, and measurements of specific surface area (BET). XRD combined to RAMAN analyses revealed that the products are two-phase highly crystalline oxides involving anatase as main phase and brookite. Besides, the refined XRD using the method of Rietveld demonstrated that the presence of acetone during the synthesis influenced in the composition of the crystalline phases, increasing the proportion of the brookite phase between 13 and 22%. The band gap energy of these oxides practically did not suffer changes as function of the synthesis conditions. As shown by the isotherm, these photocatalysts are mesoporous materials with mean diameter of pores of 7 nm and approximately 20% of porosity. The surface area of the oxides prepared by hydrolysis in presence of acetone was 12% higher compared to the bare oxide. After characterized, these oxides had their photocatalytic activities evaluated by photodegradation of the azo dyes Ponceau 4R (P4R), Tartrazine (TTZ) and Reactive Red 120 (RR120), and also by the ability to mediate the photocatalytic production of hydrogen. Using the most efficient photocatalyst, the mineralization achieved for the dyes P4R, RR120 and TTZ was of respectively 83%, 79% and 56% in 120 minutes of reaction, while the discoloration of P4R e RR120 reached 100% and 94% for TTZ. In addition, the same photocatalyst in the presence of 0.5% w/w of Platinum and suspended in a 5:1 v/v water/methanol mixture, produced 56 mmol of gaseous hydrogen in five hours of experiment, corresponding to a specific rate of hydrogen production of 139.5 mmol h-1 g-1.

Entre as tramas da indústria da moda: argumentos sobre o trabalho escravo contemporâneo na sociedade de consumo

Even after its abolition, the slave labor still exists in the world. In a new socio-historic context, the shackles and slave quarters have been left behind, nowadays the workers are tempted, subjected to degrading conditions and have their rights retrenched. The contemporary slave labor has been emerging as subject of research in the Organizational Studies since the early 2000s, calling attention to many gaps to be filled about the way organizations all around the world use this practice. Contemporary slave labor is found in many and various economic activities, since coal to textile industries or even stores. In this dissertation, we have incorporated the consumption dimension to the field of Organizational Studies, discussing the modern slavery, aiming to understand the consumers’ point of view about this topic, that is, we have researched the consumers’ interpretations concerning the slave labor in the fashion industry. Our objective is to analyze consumer’s argumentative construction in the decision of buying or not products made by industries from the fashion field that were denounced because of slave labor usage. We have adopted fashion industry as research focus because it obscures the reflection of the consumers that feel like in a new world while shopping, a world of beauty and fantasy, seeking their own satisfaction. Furthermore, the Brazilian fashion industry is one of the biggest of the world (ABIT, 2015), with a huge symbolic strength in the country. We have realized a qualitative research using semi-structured interviews with 35 consumers to identify their arguments according to the criteria defined by Liakopoulos (2002): data, propositions, guarantees, supports and refutations. The data are the statements used by the interviewees categorically, that is, those which are clear in the interviews. The propositions are what qualifies and justifies the used data. The guarantees are related to the nature of the data, they are what gives the sense to the data and are introduced implicitly in the interviewee speech. The supports are universal premises introduced in order to legitimate the arguments. The refutations, when present, counter the used arguments. As results, we’ve found consumers who developed arguments pro-consumption and anti-consumption and who have defended ideas about the responsibility of different actors for the existence of this practice and for the fight against it. From these two categories: (1) pro-consumption – consume despite the complaints and (2) anti-consumption – don’t consume, because of the accusations; we have identified the following argumentative lines: skepticism, faultfinding and moral engagement. By the end, we have presented the interviewees’ argumentative construction and the obtained results.