Título da Tese: Fracionamento das proteínas da Moringa oleifera Lam e sua funcionalização com partículas magnéticas para tratamento de corantes em soluções aquosas.


Orientadora: Profa. Dra. Angélica Marquetotti Salcedo Vieira

Data da Defesa: 31/01/2020


The presence of synthetic dyes in industrial effluents that are discharged into water bodies without treatment, is a threat to the health of humans and animals by causing imbalance in aquatic ecosystems and trigger various environmental problems. Thus, the adsorption process has emerged as an alternative to conventional processes involving chemical coagulants and an efficient and low cost operation process.
This study aims to remove synthetic anionic dyes (Reactive Black 5, Amaranth,
Sunset Yellow and Brilliant Blue) from aqueous solution through coagulation/flocculation process with a new coagulant obtained from Moringa oleifera Lam. seeds proteins and functionalized with iron oxide nanoparticles.
The food dyes used were Amaranth (AM), Sunset Yellow (SY) and Brilliant Blue
(BB), donated by the company Duas Rodas Industrial Ltda. And the textile Reactive Black 5 dye was donated by the company Texpal Química Ltda. Moringa seeds used in the trials were from Aracaju-SE. From moringa seeds it was possible to extract the proteins based on their solubility, separating them in protein fractions Albumin (Alb) and Globulin (Glo) that were functionalized with magnetic nanoparticles. From the coagulants, it was possible to perform their characterization with scanning electron microscopy (SEM), x-ray spectroscopy by
energy dispersion (XED), Fourier transform infrared spectroscopy (FTIR), coagulant a dyes zeta potential and, finally, the vibration sample magnetometry analysis (VSM). The application of a magnetic field in the sedimentation allowed fast settlement of the dyes particles and their separation. Variation of parameters such as protein concentration, nanoparticles concentration, solution pH, dye concentration and alkalinizing influence were performed. Finally, the sedimentation time was analyzed with and without the magnetic field and the reuse of iron oxide nanoparticles.
As indicated in MEV analysis, Glo protein fraction is more homogeneous and, apparently, more rigid than Alb. This fact is due to the extraction method, which fractionates the proteins according to their solubility. Furthermore, MEV shows that the nanoparticles have an irregular shape resulting from the calcination of the material obtained from heating polyvinylalcohol (PVA) solution and iron nitrate solution. EDX and FTIR analysis are compatible with natural organic materials as in the case of the seeds, and the nanoparticles spectra indicate the predominance of iron and oxygen. The VSM proved the presence of a magnetic field from the iron oxide nanoparticles. Protein reading by Lowry showed that the
protein concentration of Alb and Glo fractions were 8404.60 and 3758.26 mg L-1, respectively. From these concentrations it was possible to calculate the volume used in the testes. Based on the RP5 dye assays performed it was possible to observe that the best magnetic nanoparticles concentration was 4 g L-1, and the protein fraction that shows the best results in color removal, taking into account the viability, was Albumin. These results were chosen as standards for other dyes assays. Thus, for AM and SY the best protein concentration was 150 mg L-1, for RB5 the best was 115 mg L-1 and for BB dye, 75 mg L-1. 10
Regarding dye concentration, the best removals for AM, SY and RB5 were at concentration 20 mg L-1, reaching values near of 85, 65 and 95%, respectively. A different behavior was found for BB dye removal, which obtained better results at the concentration of 100 mg L-1. The best pH values for RB5, AM, SY and BB were 6, 3, 5, 5, respectively. The sedimentation time results showed that it is possible to decrease it with the application of the magnetic field from 1 hour to 5 minutes and the magnetic nanoparticles reuse tests prove that these can be reused in new coagulation cycles without efficiency loss.
With the development of the present study, it was possible to determine the efficiency of Moringa oleifera Lam seeds proteins functionalized with iron oxide nanoparticles. The results obtained indicate that the protein albumin was the best result in the removal of RP5 dye. From this new coagulant, it was possible to apply a magnetic field during the sedimentation process of the formed particles, which accelerated the process and also increased the efficiency of dye removal. The amaranth dye had its removal increased from 45% to 86% and the sunset yellow from 15% to 69% with the presence of the magnetic field, whereas reactive black 5 reached 94% of removal and brilliant blue reached 52%. Also, the sedimentation time decreased from 30 to 5 minutes with magnetic sedimentation. Furthermore, the magnetic nanoparticles were recovered from the residual sludge and again applied in coagulation/flocculation cycles without loss of their efficiency.

KEYWORDS: protein, moringa, dye, nanoparticles.


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