Removal of aliphatic amino acids by hybrid organic–inorganic layered compounds

Silvério, Fabiano; Reis, Márcio José dos; Tronto, Jairo; Valim, João Barros

doi:10.1016/j.apsusc.2006.12.040

Cited by 26 publications

(10 citation statements)

References 29 publications

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“…Thus, they interact strongly with solids having positive structural or pH-dependent charges. Layered double hydroxides (LDHs), also known as anionic clays, have a permanent positive structural charge and are known to exchange many organic species effectively; they are receiving increasing amounts of attention. − We present here an experimental NMR study of the behavior of 13 C-enriched glutamate (Glu) adsorbed on the prototypical LDH, hydrotalcite [HT; nominally (Mg 2 Al)(OH) 6 A − , n H 2 O, where A − is a counteranion that may bear different charges] synthesized at pH values from 9.1 to 11.0. 13 C enrichment was used to allow for the collection of MAS NMR measurements under non-crossed-polarization (CP) conditions.…”

Section: Introductionmentioning

confidence: 99%

Preferential Adsorption of Lower-Charge Glutamate Ions on Layered Double Hydroxides: An NMR Investigation

2009

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13 C MAS NMR spectroscopy of isotopically enriched samples of the layered double hydroxide hydrotalcite (HT) [(Mg 2 Al)(OH) 6 A -,nH 2 O, where Ais a counteranion that may bear different charges] exchanged with glutamate (Glu) shows an unexpected preferential adsorption of the lower-charged species (Glu 1-) relative to the higher-charged species (Glu 2-) by a layered double hydroxide (LDH) compound. At pH 11.0, the Glu 1-/ Glu 2ratio is about 0.44, an order of magnitude greater than expected in solution. Previous studies of phosphate and carbonate exchange onto LDH compounds (refs 25 and 26) show a strong preference for the highercharged anion. The preference for Glu 1-, in which the amine site is protonated, may be due in part to -NH 3 + allowing for an energetically more favorable H-bonding network among the anions, the metal hydroxide substrate, and the interlayer and surface water molecules compared to -NH 2 . Changes in the pH and the pK a of Glu near the HT surface and due to nanoconfinement may also play important roles. These results suggest that the interactions dominating the exchange of amino acids and proteins onto LDH compounds may be quite different from those that control the exchange of small inorganic anions.

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Section: Introductionmentioning

confidence: 99%

Preferential Adsorption of Lower-Charge Glutamate Ions on Layered Double Hydroxides: An NMR Investigation

2009

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“…Wherein, the use of HT as a kind of adsorbent in the water treatment was focused by many researchers. As reported, many kinds of ions, such as inorganic anions (Kuzawa et al, 2006;Yoshioka et al, 2007), organic acids (Silverio et al, 2007), and colored organics (Orthman et al, 2007;Bouraada et al, 2007), may enter the interlayer space of HT and consequently be adsorbed. Especially, after calcinations, the reconstruction of the original hydrotalcite with the positive charge layers was obtained.…”

Section: Hydrotalcite-type (Ht) Adsorbent and Its Modificationmentioning

confidence: 99%

Research progress of novel adsorption processes in water purification: A review

2008

Journal of Environmental Sciences

395

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As an effective, efficient, and economic approach for water purification, adsorbents and adsorption processes have been widely studied and applied in different aspects for a long time. In the recent years, a lot of novel adsorption processes have been developed for enhancing the efficiency of removing the organic and inorganic contaminants from water. This article reviews some new adsorbents and advanced adsorption methods that specialize in their compositions, structures, functions, and characteristics used in water treatment. The review emphasizes adsorption/catalytic oxidation process, adsorption/catalytic reduction process, adsorption coupled with redox process, biomimetic sorbent and its sorption behaviors of POPs, and modified adsorbents and their water purification efficiency.

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“…When the Glu concentration is below 1.5 mmol/g, the magnitude of zeta potential decreases to about 25 mV, providing direct evidence for the interaction of glutamic acid with LDH. After the Glu concentration exceeds 1.5 mmol/g, the reduction of the positive zeta potential becomes much lower due to the ion-exchanging of nitrate ions by glutamic acid anions has reached equilibrium but larger glutamic acid anions may migrate into the diffuse layer while increasing the glutamic acid concentration …”

Section: Results and Discussionmentioning

confidence: 99%

“…After the Glu concentration exceeds 1.5 mmol/g, the reduction of the positive zeta potential becomes much lower due to the ion-exchanging of nitrate ions by glutamic acid anions has reached equilibrium but larger glutamic acid anions may migrate into the diffuse layer while increasing the glutamic acid concentration. 42 The purpose of modifying LDH with Glu is to improve the wettability of LDH by the AKD liquid. However, AKD is solid at room temperature and has high susceptibility to hydrolytic decomposition.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Alkyl Ketene Dimer Emulsions Stabilized by Layered Double Hydroxide Particles Modified with Glutamic Acid

Song

Liu

et al. 2017

Ind. Eng. Chem. Res.

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Alkyl ketene dimer (AKD) is commonly applied as oil-in-water emulsions in the papermaking industry. Herein a particle stabilized AKD emulsion was developed to avoid the adverse effect of surfactant, further improving the sizing performance and reducing the hydrolysis of AKD emulsions, where layered double hydroxide (LDH) particles were employed as a stabilizer of the AKD emulsions after being modified with glutamic acid (Glu). The success of the modification of LDH with Glu was evidenced by high-resolution transmission electron microscopy (HRTEM), zeta potential, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) studies. Furthermore, the impact of the modification on the wettability of LDH was analyzed. It was found that the hydrophilic LDH particles became partially hydrophobic after being modified with Glu (at 1.5 mmol/g) and, thus, promoted the formation of emulsions with fine and uniform droplets that resisted creaming/coalescence formation. The adsorption of the Glu-modified LDH particles on the AKD droplet surface improved the emulsion stability, which was verified by fluorescent confocal laser scanning microscopy. Meanwhile, by using Glu-modified LDH nanoparticles, the storage stability of AKD emulsion and its sizing performance on paper were also improved.

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Removal of aliphatic amino acids by hybrid organic–inorganic layered compounds

Cited by 26 publications

References 29 publications

Preferential Adsorption of Lower-Charge Glutamate Ions on Layered Double Hydroxides: An NMR Investigation

Preferential Adsorption of Lower-Charge Glutamate Ions on Layered Double Hydroxides: An NMR Investigation

Research progress of novel adsorption processes in water purification: A review

Alkyl Ketene Dimer Emulsions Stabilized by Layered Double Hydroxide Particles Modified with Glutamic Acid

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