Banca de QUALIFICAÇÃO: LARISSA MAYARA DA SILVA GOMES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LARISSA MAYARA DA SILVA GOMES
DATE: 24/02/2025
TIME: 08:00
LOCAL: Auditório do DQ
TITLE:

DEVELOPMENT OF A SILICA-BASED MATERIAL AS A SUPPORT FOR CONTROLLED RELEASE OF CITRIC ACID IN PHYTOREMEDIATION PROCESSES IN SOILS CONTAMINATED BY NICKEL AND CHROMIUM

KEY WORDS:

Citric acid; Controlled release; Optimization of experiments; Silica; Thermal stability.

PAGES: 59
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SUMMARY:

Growing environmental contamination highlights the need to develop practices to mitigate the impacts of anthropogenic activity on natural resources. Among the most promising approaches, phytoremediation combines sustainability and economy in recovering soils contaminated by different pollutants. This work aims to develop a silica-based material to support the controlled release of citric acid (H3Cit) in the phytoremediation processes of soils contaminated by nickel and chromium. For the synthesis of the silica samples (Sil–H3Cit), a 23-factor design with a triplicate midpoint was carried out, totaling 27 experiments to evaluate the influence of the reaction parameters and optimize the synthesis conditions to obtain a material with more excellent thermal stability within the ranges studied. The infrared spectroscopic analysis of the samples (Sil–H3Cit) shows the presence of absorption peaks corresponding to the symmetrical (817 cm-1) and asymmetrical (1080 cm-1) stretching of the Si–O–Si bond, as well as peaks associated with the silanol group Si–OH (~3492 cm-1), confirming the formation of the silica samples. The characteristic acid carbonyl peaks in the 1690–1730 cm-1 region show the presence of citric acid in the silica matrices. A single mass loss event suggests that H3Cit is located in a single structural region in all the samples. In addition, the reduction in the onset temperature of the thermal event indicates that H3Cit interacts with the silica matrix by adsorption, which corroborates the objective of its controlled release. A statistical model was drawn up based on the data obtained from the thermogravimetric curves. The results, supported by the distribution of effects graph and the ANOVA analysis of variance (Prob > F = 0.0062), highlighted the number of moles of citric acid as the most influential factor in the response. The model showed a desirability of 91%, indicating high reliability. The conditions optimized to reach a thermal event end temperature of 263 °C were determined to be 6 moles of citric acid and 2 hours of reaction time at room temperature. The results highlight the potential application of the material for phytoremediation of contaminated soil.

COMMITTEE MEMBERS:
Interno - ***.826.764-** - FAUSTHON FRED DA SILVA - UFPB
Interno - JANDYSON MACHADO SANTOS
Externo à Instituição - LUIZ HENRIQUE VIEIRA LIMA - UFRPE
Presidente - MONICA FREIRE BELIAN