Banca de DEFESA: LUCAS GORITO DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LUCAS GORITO DOS SANTOS
DATE: 28/03/2024
TIME: 14:00
LOCAL: https://conferenciaweb.rnp.br/webconf/wagner-27
TITLE:

REMOVAL OF NITRATE FROM AQUEOUS SOLUTIONS BY ADSORPTION PROCESSES ON CLAY-CARBON COMPOSITES

PAGES: 124
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:

Nitrate is a species in all surface and groundwater due to its high solubility in aqueous medium. Excess nitrate in aquatic environments threatens ecosystems and human health by contributing to eutrophication, causing severe methemoglobinemia (blue baby syndrome), and being associated with the formation of nitrosamines (carcinogens). Aiming at the adsorption of nitrate in aqueous solutions, it was proposed to prepare adsorbents from the following raw materials: (1) Glycerol; (2) Clay/sewage sludge composite (LDE₁-TechPhos). The raw material (1) was hydrothermally carbonized in the presence of H₂SO₄(l) (95-99%) and FeCl₃(s), followed by pyrolysis under N_2(g) (ultra-pure) flow giving rise to CG0. Solids (1 – CG0) and (2 - LDE₁-TechPhos) were subjected to pyrolysis under NH_3(g) flow (ammonization) at different temperatures (T= 400, 600 or 800°C) and concentrations (30% NH₄OH and 5% NH₃/He, respectively), resulting in CG0₁-NH₃-T and LDE₁-NH₃-T, respectively. LDE₁-TechPhos presented low carbon content (11.2%) and oxygenated functional groups with low thermal stability, leading to adsorbents (LDE₁-NH₃-T) with limited porous structure (<34m²/g) and no adsorption capacity for nitrate (<0.1 mg/g). CG0 presented a high surface area (652 m²/g), low content of iron species (<1.1% Fe), oxygenated groups (carboxylic and sulfonated), and low pHPCZ (1.1). CG0 did not show adsorption capacity during the preliminary tests, however, the ammonization stage created a removal capacity in the glycerol activated carbons (0.2-2.8mg/g). At 400°C, the ammonization of CG0 promoted the insertion of groups N2 (amino/imine/amide - 92.1%) and N1 (pyridine - 7.9%) without increasing the pH_PCZ. At 600°C, groups N1 (pyridine - 66.8%) were predominant, added to N3 (pyrrole/lactam/pyridone/aniline – 30.7%), N5 (Pyridine oxide – 2.5%) and the elevation of your pH_PCZ (3.2). The increase in pyridine content accompanied the elevation in nitrate adsorption capacity (400°C = 0.2 mg/g and 600°C = 2.0 mg/g). At 800°C there was no insertion of nitrogenous groups due to the previous evolution of carboxylic groups (≤600°C), however, we had an increase in surface area (1034 m²/g), pH_PCZ (3.4) and greater capacity of nitrate retention (2.8 mg/g). The central composite face-centered design indicated the ideal dosage (2.0 g/L) for removing nitrate (3-30mg/L NO₃^-) by using CG0₁-NH₃-600 or CG0₁-NH₃-800. Kinetic adsorption studies for CG0₁-NH₃-600 (0.9 ± 0.1 mg/g) and CG0₁-NH₃-800 (2.1 mg/g) indicated adsorption equilibria in 60 min, both demonstrated better adjustment with the Pseudo-second order kinetic model (chemisorption). The study of adsorption isotherms indicated a better fit of the Langmuir model for CG0₁-NH₃-600 (Q_max=1.2mg/g) and Freundlich model for CG0₁-NH₃-800 (Q_max=2.4 mg/g). The intraparticle diffusion results indicated that nitrate adsorption in an aqueous medium was governed by more than one process (hydrogen bonding, electrostatic interaction, complexation and/or ion exchange) in both adsorbents (CG0₁-NH₃-600 and CG0₁-NH₃-800). Alternatively, ammonization (800°C) applied to commercial carbon (CCC -> CC-NH₃-800), which did not show nitrate adsorption capacity in our preliminary tests, generated a response of 1.1mg/g.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1601156 - WAGNER ALVES CARVALHO
Membro Titular - Examinador(a) Externo ao Programa - 163.918.148-21 - ANTÔNIO CARLOS FERREIRA BATISTA - IF UBERAB
Membro Titular - Examinador(a) Externo à Instituição - DENISE DE CASTRO BERTAGNOLLI
Membro Suplente - Examinador(a) Interno ao Programa - 1543683 - IVANISE GAUBEUR
Membro Suplente - Examinador(a) Externo ao Programa - 031.146.687-71 - GEÓRGIA CHRISTINA LABUTO ARAÚJO - UNIFESP