Effect of sodium chloride on interactions of fulvic acid and fulvate with montmorillonite

Tombácz, Etelka; Gilde, Mária; Ábrahám, Imre; Szántó, F.

doi:10.1016/0169-1317(90)90016-i

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…Wang and coauthors − have shown that the abiotic synthesis of fulvic and humic acids on the surface of clay minerals can proceed through heterogeneous catalysis (autoxidation and surface polymerization) of polyacids, gallic acid among them. Tombácz and coworkers synthesized fulvic acid on montmorillonite by heterogeneous catalysis of gallic acid with average molecular weight of 840 g/mol as determined by vapor pressure osmometry …”

Section: Introductionmentioning

confidence: 99%

“…Tombácz and coworkers synthesized fulvic acid on montmorillonite by heterogeneous catalysis of gallic acid with average molecular weight of 840 g/mol as determined by vapor pressure osmometry. 28 Overall, our synthesis of core-shell PGA@MNPs for bio-application was inspired by the environmental process of surface induced polymerization of small organic acids possessing OH moieties. Based on the analogy to humic formation in the environment, the spontaneous formation of a polygallate (PGA) shell on the MNP cores is in fact a chemical transformation under mild conditions and it should result in a persistent coating.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of in Situ Surface Polymerization of Gallic Acid in an Environmental-Inspired Preparation of Carboxylated Core–Shell Magnetite Nanoparticles

et al. 2014

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Corresponding authorsM. Szekeres (szekeres@chem.u-szeged.hu) and E. Tombácz (tombacz@chem.u-szeged.hu) Graphical abstract AbstractMagnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in-situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The Polygallate on magnetite nanoparticles Humic matter on clays 2This is a PDF file of an unedited manuscript that has been accepted for publication. Final edited form is published in Langmuir, 2014, 30:15451−15461. http://dx.doi.org/10.1021/la5038102 present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-Vis (UVvisible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection) and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering and FTIR-ATR results revealed that prior to polymerization, the GA monomers became oxidized to polycarboxylic acids due to ring opening while Fe 3+ ions reduced to Fe 2+ . Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property and biomedical applicability of the particles will be published.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of in Situ Surface Polymerization of Gallic Acid in an Environmental-Inspired Preparation of Carboxylated Core–Shell Magnetite Nanoparticles

et al. 2014

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“…Adsorption isotherms of humic acid on alumina (54,67,68), iron oxides (69-72) and manganese (73) were reported as well as the adsorption onto clays (10,(74)(75)(76). It is commonly observed that the adsorption increases with decreasing pH and in most studies the adsorption was found to increase with increasing salt concentration.…”

Section: Adsorption Of Humic Acidmentioning

confidence: 99%