resumo
The efficient removal of the antibiotic ciprofloxacin (CIP) from aqueous samples using magnetic nanosorbents prepared using three sulfated polysaccharides, kappa-, iota-, and lambda-carrageenan and an alkoxysilane agent containing a reactive epoxide ring is described. The prepared nanosorbents were characterized in detail using FTIR spectroscopy, solid-state Si-29 and C-13 NMR spectroscopy and elemental microanalysis. The synthesis method was more effective for incorporating higher amounts of kappa-carrageenan in the siliceous shells. Although being less sulfated, kappa-carrageenan is cheaper than the other carrageenan tested. The CIP adsorption was a cooperative process, well described by the Dubinin-Radushkevich isotherm, with maximum adsorption capacities of 878, 969 and 865 mg/g for kappa-, iota-, and lambda-carrageenan sorbents, respectively. Overall, the produced magnetic nanosorbents are among the best magnetic systems with high adsorptive efficiency for CIP. It is suggested that protonated CIP molecules are exchanged with ester sulfate counterions of carrageenan at the particles' surface as the main pathway for CIP adsorption. The adsorption process was exothermic and entropically favorable for the three sorbents. However, at 298 K, the adsorption was spontaneous for kappa-carrageenan-based sorbents and non-spontaneous for iota- and lambda-carrageenan particles. The magnetic sorbents could be reused and maintained their ability towards CIP removal up to four cycles. The removal efficiency in wastewater was enhanced with the sorbent dose. [GRAPHICS] .
palavras-chave
HOSPITAL WASTE-WATER; ACTIVATED CARBON; AQUEOUS-SOLUTIONS; REMOVAL; SORPTION; NANOCOMPOSITE; OPTIMIZATION; ANTIBIOTICS; SURFACE; SPECTROSCOPY
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Soares, SF; Nogueira, J; Trindade, T; Daniel-da-Silva, AL
nossos autores
Ana Luísa Daniel da Silva
Investigador Principal
João Nogueira
Bolseiro de investigação
Sofia Soares
Investigador Júnior
Tito Trindade
Professor CatedráticoProjectos
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)
Projeto de Investigação Exploratória: Ana Luísa Silva (IF/00405/2014)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). The authors thank the RNME (National Electronic Microscopy Network) for microscopy facilities. S. F. Soares thanks the FundacAo para a Ciencia e Tecnologia (FCT) for the PhD Grant SFRH/BD/121366/2016. J. Nogueira thanks the FundacAo para a Ciencia e Tecnologia (FCT) for the PhD Grant SFRH/BD/146249/2019. A. L. D.-d.-S. acknowledges FCT for the research contract under the Program' Investigador FCT' 2014 and for funding from the project IF/00405/2014.