Banca de DEFESA: Helzalyce Rocha Novaes

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Helzalyce Rocha Novaes
DATE: 27/10/2023
TIME: 14:30
LOCAL: Sala de Informática do PTARH com Transmissão pela Plataforma MS Teams
TITLE:

Cylindrospermopsin removal onto activated carbons synthesized from coconut shell.

KEY WORDS:

adsorption, activated carbon, cylindrospermopsins, fixed bed adsorption columns, rapid small-scale column tests (ERCER), oxidation of activated carbons.

PAGES: 115
BIG AREA: Engenharias
AREA: Engenharia Sanitária
SUBÁREA: Recursos Hídricos
SUMMARY:

Cylindrospermopsin (CYN) is a toxic metabolite produced by several species of cyanobacteria. CYN can be dissolved in high proportions in aquatic environments, including water sources for human supply, thus representing a challenge for water treatment plants (WTPs). Therefore, it is necessary to use advanced drinking water treatment methods in addition to conventional systems. Amongst them, adsorption onto activated carbon (AC) has proven to be a promising and cost-effective alternative. So, the present work evaluated CYN adsorption onto two ACs with different acidic degrees. The adsorbents were synthesized as follows. Firstly, a starting mesopore-rich AC was prepared by chemical activation of coconut shells with H3PO4. Then, this AC was submitted to (i) treatment with HNO3, which gave rise to an AC rich in acidic oxygenated functional groups (ACOx); (ii) a heat treatment at 850 °C under an inert atmosphere, which rendered a much less acidic AC (ACHT). The kinetic tests were carried out in two study waters with different matrices: ultrapure water and ultrafiltered surface water from Lake Paranoá WTP (Brasília - DF). Equilibrium adsorption tests were carried out only in the ultrapure water matrix. The AC with the best performance in adsorption tests was also evaluated in the granular form through rapid small-scale column tests (RSSCTs). In both study waters, ACOx and ACHT fitted slightly better the pseudo-second-order model. Also, film diffusion was the limiting phase for toxin adsorption in the initial contact hours, followed by intraparticle distribution close to the equilibrium condition. The equilibrium adsorption data fitted the Langmuir isotherm model the better for both ACs. Despite its lower porosity and specific surface area, ACHT yielded better results in terms of kinetics and adsorption capacity (k2 ultrapure water = 0.0083 min-1; k2 ultrafiltered Lake Paranoá water = 0.025 min-1; qmax ultrapure water = 2.52 µg/mg). The RSSCT tests were conducted with ACHT in the ultrafiltered Lake Paranoá water matrix. The estimated breakthrough for a full-scale adsorption column was 28.4 days, for an initial toxin concentration of 15 µg/L and an empty bed contact time (EBCT) of 10 minutes.

COMMITTEE MEMBERS:
Externa à Instituição - EDUMAR RAMOS CABRAL COELHO - UFES
Interna - 1122604 - CRISTINA CELIA SILVEIRA BRANDAO
Interna - 1509161 - RAQUEL MORAES SOARES
Presidente - 1646057 - YOVANKA PEREZ GINORIS