abstract
Graphene-based materials are attractive adsorbents for water decontamination. In this work, we have produced eco-friendly reduced graphene oxide (rGO)-based sorbents by the hydrothermal reduction of graphene oxide (GO) in presence of caffeic acid (CA) and further modification with chitosan (CA_CS). Scanning electron microscopy observations show porous macrostructures that turn more compact after CA or CA_CS modification. The specific surface area achieves a maximum value of 293 m(2) g(-1) for the pristine rGO foam. The macropores are mainly distributed in a range between 1-170 mu m. The Hg2+ removal efficiency of the rGO-based foams was investigated across several different parameters. The foam modified with caffeic acid exhibited the most promising performance, demonstrating the highest removal efficiency at pH 4-6, with a maximum sorption capacity of 2.79 mg/g as determined by the Sips equation. Kinetic analysis indicates that intraparticle diffusion and the sorption itself are the rate-limiting steps. The notable sorption efficiency, the low desorption rate, and the applicability in real complex water matrices, including tap water, position rGO_CA as a viable material for efficiently capturing Hg(II) from large volumes of water and securely storing it in a small solid volume.
keywords
AQUEOUS-SOLUTIONS; MERCURY IONS; REMOVAL; ADSORPTION; CHITOSAN; HG(II); GASES; ORDER; MODEL
subject category
Engineering
authors
Barra, A; Carvalho, A; Lopes, CB; Ruiz-Hitzky, E; Nunes, C; Ferreira, P
our authors
Ana Barra
Junior Researcher
Cláudia Batista Lopes
Assistant Researcher
Cláudia Nunes
Assistant Researcher
Paula Celeste da Silva Ferreira
Coordinating ResearcherGroups
G1 - Porous Materials and Nanosystems
G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy
Projects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MEC (PIDDAC). AB is thankful to FCT for grant SFRH/BD/148856/2019 and CBL for researcher contract (DOI 10.54499/2021.03739.CEECIND/CP1659/CT002). CN is grateful to Portuguese national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. E.R.-H. acknowledges financial support by the MCIN/AEI/10.13039/501100011033 (Spain, project PID2019-105479RB-I00). The authors want to acknowledge COST Action NETPORE, CA20126, supported by COST (European Cooperation in Science and Technology).