Proton magnetic resonance studies of the structure of water in Dowex 50W

Howery, Darryl G.; Shore, Lawrence; Kohn, Barry H.

doi:10.1021/j100648a021

Cited by 11 publications

(11 citation statements)

References 17 publications

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“…The binding site in both Amberlyst ® -15 and AG ® 50W-X4 is a sulfonate group [101], whereas the findings presented here indicate that carboxylate groups are mainly responsible for binding in glucose hydrochar and especially AA-hydrochar. The sulfonic acid group is at least 1000× stronger than the carboxylic acid group, meaning that this difference could explain sorption behavior and the need for alkali activation.…”

Section: Custom-synthesis Of Hydrochar For Heavy Metal Adsorptionmentioning

confidence: 50%

“…Interestingly, AG ® 50W-X4 far exceeds all other sorbents on effectiveness per acid site, with nearly two Cu ions associated with every acid site ( Figure 6). The difference between AG ® 50W-X4 and Amberlyst ® -15 is noteworthy as both sorbents are described in the literature as polymerized styrene backbones with periodic sulfonic acid group substitution [101]. The difference in their performance must be due either to (1) the ability of the sorbent to hold charge, which could be saturated for Amberlyst ® -15 limiting its sorption capacity, (2) differences in acid site accessibility in the swollen resins and hydrochars, or (3) differences in the spatial proximity of the acid binding groups in the different sorbents.…”

Section: Custom-synthesis Of Hydrochar For Heavy Metal Adsorptionmentioning

confidence: 99%

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Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

et al. 2020

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A model hydrochar was synthesized from glucose at 180 °C and its Cu(II) sorption capacity was studied experimentally and computationally as an example of molecular-level adsorbent design. The sorption capacity of the glucose hydrochar was less than detection limits (3 mg g−1) and increased significantly with simple alkali treatments with hydroxide and carbonate salts of K and Na. Sorption capacity depended on the salt used for alkali treatment, with hydroxides leading to greater improvement than carbonates and K+ more than Na+. Subsequent zeta potential and infrared spectroscopy analysis implicated the importance of electrostatic interactions in Cu(II) sorption to the hydrochar surface. Computational modeling using Density Functional Theory (DFT) rationalized the binding as electrostatic interactions with carboxylate groups; similarly, DFT calculations were consistent with the finding that K+ was more effective than Na+ at activating the hydrochar. Based on this finding, custom-synthesized hydrochars were synthesized from glucose-acrylic acid and glucose-vinyl sulfonic acid precursors, with subsequent improvements in Cu(II) adsorption capacity. The performance of these hydrochars was compared with ion exchange resins, with the finding that Cu(II)-binding site stoichiometry is superior in the hydrochars compared with the resins, offering potential for future improvements in hydrochar design.

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Section: Custom-synthesis Of Hydrochar For Heavy Metal Adsorptionmentioning

confidence: 50%

Section: Custom-synthesis Of Hydrochar For Heavy Metal Adsorptionmentioning

confidence: 99%

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

et al. 2020

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“…23–26 These studies, however, did not address the dynamics of water lying outside the polymers or tissues.…”

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confidence: 99%

Impact of Hydrophilic Surfaces on Interfacial Water Dynamics Probed with NMR Spectroscopy

Yoo

Paranji

Pollack

2011

J. Phys. Chem. Lett.

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In suspensions of Nafion beads and of cationic gel beads, NMR spectroscopy showed two water–proton resonances, one representing intimate water layers next to the polymer surface, the other corresponding to water lying beyond. Both resonances show notably shorter spin–lattice relaxation times (T1) and smaller self-diffusion coefficients (D) indicating slower dynamics than bulk water. These findings confirm the existence of highly restricted water layers adsorbed onto hydrophilic surfaces and dynamically stable water beyond the first hydration layers. Thus, aqueous regions on the order of micrometers are dynamically different from bulk water.

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“…Thus, the technique can be used for the characterization of cation and anion resins. Properties such as crosslinking, homogeneity, internal concentration of counterions, rate of exchange of water, hydration of counterions in the resin phase, and similarities between concentrated homogeneous solutions of electrolytes and the heterogeneous water-resin system have been evaluated (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). In some More recently, NMR has been used to study macroreticular (porous) ion exchange resins (18)(19)(20).…”

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confidence: 99%

Nuclear magnetic resonance study of the interaction between cation exchange resins and alcohol and water-alcohol mixtures

Casey¹,

Pietrzyk²

1973

Anal. Chem.

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Nuclear magnetic resonance data are reported for hydrogen-form, strongly acidic, cation exchange resins in water, methanol, ethanol, n-propanol, n-butanol, and water-alcohol mixtures. Gel and macroreticular (porous) type resins were investigated. The effect of crosslinking was considered in the gel type resin. A downfield shift in the peak for internal solvent was observed as a function of type of solvent. This behavior is discussed in terms of solvation of the sulfonic acid exchange sites on the resin. An observed shift for the interior solvent NMR peak in mixed solvent is discussed as a function of solvent composition. Comparison is made to p-toluenesulfonic acid in mixed solvent. Supporting data collected in mixed solvents were solvent uptake and solvent preference. Effects due to particle size, type of resin, and broadening are discussed. of these investigations, mixed solvents have been considered (9-11). Macro water levels in ion exchange res-1 Present address, American Machine and Foundry Company,

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Proton magnetic resonance studies of the structure of water in Dowex 50W

Cited by 11 publications

References 17 publications

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

Impact of Hydrophilic Surfaces on Interfacial Water Dynamics Probed with NMR Spectroscopy

Nuclear magnetic resonance study of the interaction between cation exchange resins and alcohol and water-alcohol mixtures

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