Surface Charge Density Determination in Water Based Magnetic Colloids: a Comparative Study

Campos, Alex Fabiano Cortez; Medeiros, Webert Costa de; Aquino, Renata; Depeyrot, J.

doi:10.1590/1980-5373-mr-2017-0649

Cited by 11 publications

(5 citation statements)

References 23 publications

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“…K eq + and K eq − respectively denote the surface stability constants, while the on the lined species belong to the solid phase. The pKa of and are respectively 1.44, and 4.66 [ 28 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

Statistical optimization of amorphous iron phosphate: inorganic sol–gel synthesis-sodium potential insertion

et al. 2021

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Iron phosphate, Fe2 (HPO4)3*4H2O, is synthesized at ambient temperature, using the inorganic sol–gel method coupled to the microwave route. The experimental conditions for the gelling of Fe (III)-H3PO4 system are previously defined. Potentiometric Time Titration (PTT) and Potentiometric Mass Titration (PMT) investigate the acid–base surface chemistry of obtained phosphate. Variations of surface charge with the contact time, Q a function of T, are examined for time contact varying in the range 0–72 h. The mass suspensions used for this purpose are 0.75, 1.25 and 2.5 g L−1. The point of zero charge (PZC) and isoelectric point (IEP) are defined using the derivative method examining the variations $$\frac{{{\text{dpH}}}}{{{\text{d}}t}} = f\left( {{\text{pH}}} \right)$$ dpH d t = f pH , at lower contact time. A shift is observed for PZC and IEP towards low values that are found to be 2.2 ± 0.2 and 1.8 ± 0.1, respectively. In acidic conditions, the surface charge behavior of synthesized phosphate is dominated by $$\overline{{ > {\text{POH}}}}$$ > POH ¯ group which pKa = 2.45 ± 0.15. Q against T titration method is performed for synthesized Fe2 (HPO4)3*4H2O in NaCl electrolytes. The maximal surface charge (Q) is achieved at the low solid suspension. Hence, for m = 0.75 g L−1, Q value of 50 coulombs is carried at μ = 0.1 and pH around 12, while charge value around 22 coulombs is reached in the pH range: 3–10. The effect of activation time, Q and pH on sodium insertion in iron phosphate, were fully evaluated. To determine the optimal conditions of the studied process, mathematical models are used develop response surfaces in order to characterize the most significant sodium interactions according to the variation of the pH, Q, the contact time and the contents of the synthesized material.

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Section: Resultsmentioning

confidence: 99%

Statistical optimization of amorphous iron phosphate: inorganic sol–gel synthesis-sodium potential insertion

et al. 2021

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“…Figure 6 shows the zeta potential as a function of pH for the PACo–Lys and PACo samples ( Figure 6 a), and the PACoM and PACoM–Lys samples ( Figure 6 b). The pH dependence of the zeta potential of the precursor nanoparticles has been already explored [ 34 , 35 ], and it is related to the number of ≡FeOH 2 + and ≡FeO − surface sites, which are predominant in acidic and alkaline mediums, respectively. In the case of the nanoadsorbents, the charge regulation may be explained based on the balance of the deprotonation of carboxyl groups (pKa~2.2) and ammonium groups (pKa~9.1 and ~10.8) of the L-lysine layer.…”

Section: Resultsmentioning

confidence: 99%

L-Lysine-Coated Magnetic Core–Shell Nanoparticles for the Removal of Acetylsalicylic Acid from Aqueous Solutions

et al. 2023

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Nanotechnologies based on magnetic materials have been successfully used as efficient and reusable strategies to remove pharmaceutical residuals from water. This paper focuses on the fabrication, characterization, and application of ferrite-based magnetic nanoparticles functionalized with L-lysine as potential nanoadsorbents to remove acetylsalicylic acid (ASA) from water. The proposed nanomaterials are composed of highly magnetic and chemically stable core–shell nanoparticles covered with an adsorptive layer of L-lysine (CoFe2O4–g-Fe2O3–Lys). The nanoadsorbents were elaborated using the coprecipitation method in an alkaline medium, leading to nanoparticles with two different mean sizes (13.5 nm and 8.5 nm). The samples were characterized by XRD, TEM, FTIR, XPS, Zetametry, BET, and SQUID magnetometry. The influence of time, pH, and pollutant concentration was evaluated from batch studies using 1.33 g/L of the nanoadsorbents. The Freundlich isotherm best adjusted the adsorption data. The adsorption process exhibited a pseudo-second-order kinetic behavior. The optimal pH for adsorption was around 4-6, with a maximum adsorption capacity of 16.4 mg/g after 150 min of contact time. Regeneration tests also showed that the proposed nanomaterials are reusable. The set of results proved that the nanoadsorbents can be potentially used to remove ASA from water and provide relevant information for their application in large-scale designs.

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“…However, a charge density as large as has been reported in magnetic nanoparticles suspended in polar solvents. If such large charge densities can be realised in particles of radius , the parameter for such particles is (Brown et al 2013; Campos et al 2017). The parameter is much smaller, about for particles with diameter , charge density 1 C m and , where is expressed in .…”

Section: Discussionmentioning

confidence: 99%

A suspension of conducting particles in a magnetic field – the particle stress

Kumaran

2020

J. Fluid Mech.

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Surface Charge Density Determination in Water Based Magnetic Colloids: a Comparative Study

Cited by 11 publications

References 23 publications

Statistical optimization of amorphous iron phosphate: inorganic sol–gel synthesis-sodium potential insertion

Statistical optimization of amorphous iron phosphate: inorganic sol–gel synthesis-sodium potential insertion

L-Lysine-Coated Magnetic Core–Shell Nanoparticles for the Removal of Acetylsalicylic Acid from Aqueous Solutions

A suspension of conducting particles in a magnetic field – the particle stress

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