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Article

Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

1
Department of Science, University Centre of Defence at the Spanish Air Force Academy, Ministry of Defence-Technical University of Cartagena, C/Coronel López Peña s/n, Santiago de la Ribera, 30720 Murcia, Spain
2
Campus Alfonso XIII, Technical University of Cartagena, 30203 Cartagena, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Zhenli He
Water 2021, 13(13), 1757; https://doi.org/10.3390/w13131757
Received: 22 May 2021 / Revised: 13 June 2021 / Accepted: 22 June 2021 / Published: 25 June 2021
(This article belongs to the Special Issue Remediation of Contaminated or Degraded Soil and Water Resources)
This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increased. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters. View Full-Text
Keywords: adsorption; magnetic nanoparticles; nitrate; pollutant removal; water remediation adsorption; magnetic nanoparticles; nitrate; pollutant removal; water remediation
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MDPI and ACS Style

Vicente-Martínez, Y.; Caravaca, M.; Soto-Meca, A.; Martín-Pereira, M.Á.; García-Onsurbe, M.d.C. Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters. Water 2021, 13, 1757. https://doi.org/10.3390/w13131757

AMA Style

Vicente-Martínez Y, Caravaca M, Soto-Meca A, Martín-Pereira MÁ, García-Onsurbe MdC. Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters. Water. 2021; 13(13):1757. https://doi.org/10.3390/w13131757

Chicago/Turabian Style

Vicente-Martínez, Yesica, Manuel Caravaca, Antonio Soto-Meca, Miguel Á. Martín-Pereira, and María d.C. García-Onsurbe 2021. "Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters" Water 13, no. 13: 1757. https://doi.org/10.3390/w13131757

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