https://repositorio.ufu.br/handle/123456789/19021 Thu, 17 Sep 2026 12:06:40 GMT 2026-09-17T12:06:40Z https://repositorio.ufu.br/handle/123456789/50243 Title: Estudo da redução do teor de óxidos de ferro na produção industrial de ácido fosfórico Abstract: Phosphoric acid is the second most produced and consumed inorganic acid in the world and the most important chemical intermediate in the production of phosphate fertilizers, serving as raw material for all high concentration phosphates. The agronomic potential of fertilizers produced with phosphoric acid is highly dependent on its contaminant levels, especially iron oxides. The presence of various iron oxides on phosphate rocks or concentrates can generate fertilizers containing iron phosphates, which are partially soluble on neutral ammonium citrate (NAC) and water-insoluble, therefore of lesser agronomic and commercial value. Approximately 95% of the phosphate rocks used in Brazil originates from igneous mines, on which iron oxides are the main contaminants and its total removal during the rocks` beneficiation is technical and economically unfeasible. Aiming at improving the phosphoric acid quality for fertilizer production, as well as enabling the use of phosphate concentrates with high contaminant levels as raw material for its production, the present work had as objective the development of routes enabling the removal of iron oxides from the acid. Preliminary bench tests of 43 different purification routes led to 4 potential processes, which were mapped through the Central Composite Design (CCD) technique. The experimental designs results showed that up to 75% of the Fe2O3 was removed from phosphoric acid by the usage of aminotris(methylenephosphonic acid) on the defined temperature and precipitation time. To validate the developed route, a pilot test followed by two industrial trials conducted on a 900 t P2O5/day industrial site, on which were consumed 50 metric tons of test reagent. The trials indicated technical and industrial viability for the iron oxides removal thus leading to consequent purification of phosphoric acid. Mon, 30 Jul 2018 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50243 2018-07-30T00:00:00Z https://repositorio.ufu.br/handle/123456789/49834 Title: Application of membrane separation processes to purify and concentrate bioactive extracts from annatto seeds (Bixa orellana L.) Abstract: The growing demand for natural colorants and functional compounds highlights the strategic potential of annatto (Bixa orellana L.), especially due to the presence of bixin, norbixin, and phenolic compounds. However, conventional extraction and purification methods still present limitations regarding efficiency, sustainability, and environmental impact. In this context, membrane separation processes emerge as an innovative and environmentally responsible alternative, capable of producing purer, more stable extracts with higher added value, in line with current industrial and regulatory requirements. This study aimed to investigate the application of polymeric and ceramic membranes for the purification and concentration of bioactive compounds from annatto seed extracts, with emphasis on the influence of membrane structure and material on the retention efficiency of bixin, phenolic compounds, and the associated antioxidant potential. The methodology encompassed the production of alumina-based hollow fiber ceramic membranes, subsequently characterized in terms of morphology, mechanical strength, chemical stability, and filtration performance. In parallel, experiments were conducted using polymeric membranes in a dead-end configuration, with the aim of evaluating their selectivity and retention capacity of bioactive compounds. Furthermore, the use of natural deep eutectic solvents, classified as a green alternative, was investigated for bixin extraction, with results compared to those obtained by conventional solvents, such as ethanol and water. The resulting samples were analyzed using chromatographic techniques, including high-performance liquid chromatography and mass spectrometry, enabling the precise quantification of bixin and phenolic compounds. The main results revealed that polymeric membranes with a molecular weight cut-off (MWCO) of 5 kDa were able to retain up to 90% of bixin and approximately 54.2% of phenolics compounds. The microfiltration ceramic hollow fiber membranes showed similar performance, reaching retentions close to 90% of bixin and 47,53% of phenolics compounds. The final permeate fluxes with polymeric and ceramic membranes were of 10.72 and 9,26 L h-1 m-2, respectively. Thus, both membranes were efficient for the concentration of bioactive compounds from annatto seed extracts, which reinforces the role of additional retention mechanisms in addition to the pore size exclusion. Results regarding the use of natural deep eutectic solvents confirmed not only higher extraction efficiency but also demonstrated their ability to stabilize bixin, preventing its degradation and ensuring greater preservation of bioactive properties. In these trials, the maximum yield reached 2.31% (w/w), while the ethanol:water mixture (1:1 v/v) yielded only 0.0075% (w/w) for bixin extraction. In addition to the superior performance, the extracts obtained were richer in bixin and showed greater stability compared to those produced by conventional solvents, reinforcing both the technical feasibility and the environmentally sustainable contribution of green solvents over the evaluated alternatives. It is concluded that membrane separation processes associated with natural deep eutectic solvents represent a promising route for the valorization of annatto seeds, by combining technical efficiency, sustainability, and feasibility of industrial-scale application. This study contributes to broadening the understanding of the use of clean technologies in obtaining natural colorants and bioactive compounds, providing foundations for the development of innovative processes aimed at the food, pharmaceutical, and cosmetic industries. Wed, 29 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49834 2026-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/49147 Title: Investigação numérica e experimental de sistemas de concentração solar com lentes de Fresnel para desinfecção de água Abstract: Universal access to water is one of the United Nation’s 17 sustainable development goals and a fundamental human right. However, factors such as extreme poverty, geographical isolation, and climate change pose challenges to ensuring access to safe water for populations located mainly in rural communities in underdeveloped and developing countries. Among the existing technologies for water treatment in remote regions, solar water disinfection (SODIS) stands out, which can be intensified by solar concentrators that increase the intensity of sunlight, shortening the time required for exposure and increasing the rate of microorganism inactivation. This study evaluated the potential of alternative solar concentrators, such as point and linear Fresnel lenses, in photoactivated processes such as SODIS using computational fluid dynamics to solve the equations of momentum, radiation, and species transport. To this end, two experimental units and their respective computational models were developed and validated experimentally through actinometry with potassium ferrioxalate, and a simulation design was conducted to evaluate the effect of operational variables on the main responses that characterize the performance of these concentrators. A mechanistic model of E. coli disinfection based on the generation of reactive oxygen species (ROS) and inactivation of cell protection enzymes available in the literature was implemented in the computational models to enable the numerical evaluation of the performance of these Fresnel lens concentrator systems. The results obtained indicate that the computational models developed reproduced the radiation and velocity fields properly, and a high potential for radiation intensification in the reactors was observed using the lenses. In the linear Fresnel concentrator system, it was found that the recirculation flow rate has a small effect on the reaction rate within the range of 0.4 L·min-1 to 3.95 L·min-1, and the conversion depends mainly on the position of the reactor and solar irradiation. Disinfection kinetics results showed that for the point lens it is important to ensure adequate radiation distribution, while in the unit with a linear lens it is necessary to seek a balance between increasing the fluid’s residence time in the reactor and the fluid dynamics inside the tubular reactor. Both solar concentrator systems were able to substantially reduce the treatment time of conventional SODIS to just a few minutes of operation, based on the dimensions of the development of the experimental rigs. Tue, 29 Jul 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49147 2025-07-29T00:00:00Z https://repositorio.ufu.br/handle/123456789/48941 Title: Investigação da produção de Biohidrogênio por Fotofermentação utilizando Bactérias Púrpuras não Sulfurosas na presença de Barita e Basalto Abstract: Hydrogen stands out as a clean and promising fuel, especially when produced from biomass. The current study aimed to evaluate the biological production of hydrogen using rock (Basalt) and ore (Barite) in a fermentation medium, with the intention of favoring microbial activity or promoting cell stabilization and employing in the medium non-sulfur purple bacteria associated in a 1:1:1 ratio: Rhodobacter capsulatus, Rhodospirillum rubrum, and Rhodopseudomonas palustris. As carbon sources, lactose from whey permeate powder, a co-product of the agro-industry, and glucose P.A., both at a concentration of 20 g/L, were used. The control test with lactose resulted in a productivity of 16.67 ± 0.361 mmol H₂/(L·day)], higher than that of glucose [11.35 ± 0.363 mmol H₂/(L·day)]. The presence of Barite in the culture medium increased hydrogen productivity by 12-fold compared to the control [215.32 ± 3.22 mmol H₂/(L·day)], while Basalt resulted in a 6-fold increase [109.28 ± 4.53 mmol H₂/(L·day)]. The most efficient condition in terms of hydrogen productivity, among the lactose concentrations tested (15, 20, 25 and 30 g/L), using Barite and culture medium with molybdate, was 20 g/L. Next, a factorial design was carried out in which the inoculum density and Barite concentration were evaluated and validated. The central point (0.2 gvs/L of inoculum and 0.27 g/L of Barite) was considered operationally optimal, resulting in 213.40 ± 3.80 [mmol H₂/(L·day)]. The Basalt was also subjected to chemical treatments using NaOH, HCl, and H₂SO₄ to hydrogen productivity increases. Among the treatments evaluated, the treatment with NaOH showed the highest performance, resulting in a productivity of 185.23 ± 4.25 [mmol H₂/(L·day)], higher than the value observed in the control condition 124.95 ± 4.37 [mmol H₂/(L·day)]. Among the chemical treatments with NaOH evaluated (15, 20, 25 and 30%), using Basalt, the treatment with 20% NaOH presented the highest hydrogen productivity. Finally, after carrying out a factorial design in which the inoculum density and the concentration of the treated rock were evaluated and validated, the point corresponding to 0.230 gSV/L of inoculum and 0.365 g/L of treated rock was considered operationally optimal, resulting in a production of 193.89 ± 4.37 [mmol H₂/(L·day)]. Mon, 09 Feb 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48941 2026-02-09T00:00:00Z