Banca de QUALIFICAÇÃO: ARIELLE JOICE FONSECA LOPES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : ARIELLE JOICE FONSECA LOPES
DATE: 06/10/2023
TIME: 09:30
LOCAL: Virtual
TITLE:

USE OF LIGNIN NANOPARTICLES FROM CORCOB AS STABILIZER OG OIL/WATER PICKERING EMULSIONS

KEY WORDS:

lignin, nanoparticles,  pickering emulsion.

PAGES: 68
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Tecnologia Química
SPECIALTY: Produtos Naturais
SUMMARY:

Plant biomass has three main structural components: cellulose, hemicellulose, and lignin. Cellulose-based products are widely consumed by the population, from packaging, and fuels to energy storage devices, while hemicellulose is used to obtain industrial solvents, such as furfural. Lignin has been applied to obtain heat and electricity in pulp and paper mills. However, it is estimated that the recommended energy of 15%-30% of Kraft lignin, the main lignin technique, is sufficient to maintain the operation of industrial pulp and paper plants, so there is a surplus of the biopolymer. Thus, the improvement of lignin and the development of new applications are na expanding field of research. In this context, the present work aims to add value to lignin, particularly as a stabilizer. The study investigates the performance of lignin nanoparticles as stabilizers of oil-water Pickering emulsions. To this end, corn cob lignin, obtained through alkaline removal, was used. To improve the emulsifying properties of the compound, Chemical oxidation and acetylation reactions were carried out, in addition to the addition of surfactante sodium dodecyl sulfate (SDS), to obtain four different types of lignin. Furthermore, Pickering emulsions were prepared with different concentrations of lignin nanoparticles and using diferente hydrophobic liquids: corn oil, toluene, and n-octanol, to evaluate both the performance of the lignin and the stability of the different systems. Initially, tests were carried out to characterize the lignins, such as their UV profile, FTIR spectra, and manipulation profile in the face of heating by Thermogravimetry. The results of these tests, supported by the literature, indicate the occurrence of the expected chemical modifications, observed by changes in the profile of oxidized, acetylated, and SDS lignins, compared to unmodified lignin. Then, to evaluate the performance of lignin nanoparticles, the average zeta potential and polydispersity of oxidized, acetylated, and SDS-added lignins, as well as the particle size after modification. The results demonstrate that modified lignins, in general, have a higher zeta potential in modulus than the unmodified one, as the latter presented potential of 0.18 and the others of -2.13, -20.44 and 0. 9. A similar increase was observed in polydispersity, which presented a rate of 38.3% in unmodified lignin, 41.1% in acetylated lignin, 94.65% in lignin with SDS and 30.3% in oxidized lignin, which was an exception to the increasing trend and presented values. Regarding size, there was an increase in the size of the modified lignins, which was not expected and may have resulted from particle agglomeration. After analyzing Pickering emulsions, the results show that, in general, the higher the lignin concentration, the more intense the color of the system, the higher the emulsification index, the smaller the diameter of the emulsion droplets, and the greater the number of microcapsules formed. , which converges to a high efficiency of the biopolymer in stabilizing the systems. Furthermore, regarding the systems, toluene had the best performance in emulsification rates, followed by corn oil and n-octanol. Comparing the types of lignins, it was found that the acetylated and surfactant lignins obtained higher emulsification rates and considerably smaller particle diameters compared to the oxidized and unmodified lignins, whose diameters reached twice the diameter of the acetylated lignin and with SDS, under the same conditions. Finally, we observed that almost all lignins led to the formation of PCL microcapsules, except acetylated lignin at a concentration of 1g/L, so that precipitate formation occurred. However, even in this case, increasing the lignin concentration to 2g/L made the formation of microcapsules possible. The sum of the results. The sum of the results converges to the conclusion that lignin has properties that favor its use as a surfactant and, in particular, enable the formation of biodegradable microcapsules, leaving open a field of possibilities for future work capable of developing uses and applications of microcapsules formed from lignin.

COMMITTEE MEMBERS:
Presidente - 1584174 - DOMINGOS FABIANO DE SANTANA SOUZA
Interno - 3304882 - CARLOS EDUARDO DE ARAÚJO PADILHA
Interno - 1547970 - JACKSON ARAUJO DE OLIVEIRA
Externo à Instituição - ANDERSON ALLES DE JESUS - UFMA