Banca de DEFESA: Natália Cristina Fernandes Machado

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Natália Cristina Fernandes Machado
DATE: 18/12/2020
TIME: 14:00
LOCAL: Portal RNP
TITLE:

Synthesis and characterization of the Fe/activated carbon composite from polystyrene foams: a new magnetic adsorbent for the removal of organic contaminants

 

KEY WORDS:

activated carbons, magnetism, composites, iron, adsorption

PAGES: 89
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química de Interfaces
SUMMARY:

Recently, activated carbons (CAs) derivated from plastic waste have been highlighted
in the removal of contaminants due to their excellent textural properties and high adsorption
capacity for organic contaminants. Obtaining CAs with magnetic properties makes them even
more attractive, due to the technical easiness to its removing from the bulk of aqueous
solutions. In this sense, two CAs, magnetic (CAM) and a non-magnetic (CA), are synthesized
from expanded polystyrene (EPS) residues. Both are prepared through of carbonization of
EPS dissolved in ethyl acetate (containing iron (III) tris(acetylacetonate) for magnetic), with
chemical activation by KOH at 800 ºC. This work reports for the first time the direct synthesis
of a magnetic activated carbon composite derivated from PS.
The materials are characterized by N2 adsorption/desorption, X-ray diffraction,
thermogravimetry, scanning electron microscopy (SEM), Mössbauer spectroscopy and zeta
potential. The iron phases present in the CAM are: Fe0, Fe3C and Fe3O4; being the last one
responsible for the material's magnetism. The high specific surface areas and the total volume
of CAM pores are highlighted and are equal to 672.41 m2/g and 0.345 cm3/g, respectively.
Despite of the lower values of these textural properties in relation to CA, these are still situated
among the highest valeus found in the literature of magnetic composites.
Considering the application of CAs, the materials are evaluated in the removal of the
following contaminants: methylene blue (AM), indigo carmine (IC) and hydroxybenzene
(FE). For CAM, the maximum adsorbed amounts of AM, IC and FE correspond to 275, 536
and 116 mg/g in the optimal pH. In the optimal pH and at 25 °C, the kinetics and adsorption
isotherms are studied and the thermodynamic properties are calculated by a model from
statistical mechanics. Finally, the capacity of regeneration of the CAs as adsorbents is
available in 5 cycles, with emphasis on CAM that retain 60% of its removal capacity, while
CA is able to retain only 20%

BANKING MEMBERS:
Externo à Instituição - JOÃO PAULO CAMPOS TRIGUEIRO - IFMG
Interno - PATTERSON PATRICIO DE SOUZA
Presidente - PAULO FERNANDO RIBEIRO ORTEGA
Interna - PRISCILA PEREIRA SILVA CALDEIRA