Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

Kumar, K. Vasanth; Gadipelli, Srinivas; Wood, Barbara A.; Ramisetty, Kiran A.; Stewart, Andrew; Howard, Christopher A.; Brett, Dan J. L.; Rodriguez-Reinoso, F.

doi:10.1039/c9ta00287a

Cited by 194 publications

(88 citation statements)

References 112 publications

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“…64,65 Better correlation coefficient r 2 = 0.991 for the Langmuir model ( Figure 3f) supported our hypothesis that uranyl molecules were diffused through the NNRG and allowed monolayer adsorption on the finite number of identical sites of NNRG. 65,67,70 Freundlich model with poor correlation coefficient r 2 =0.514 (Figure 3f), further confirmed that multilayer adsorption was not happening. Sips model (Langmuir-Freundlich model) with moderate fitting and evaluated value of n = 1.03 suggested adsorption of ~1 uranyl molecule per free adsorbent site ( Figure 3f).…”

Section: Isotherms For Uranium Adsorptionmentioning

confidence: 60%

“…71 The discrepancies here in pK1 fitted q e (233.7 mg/g) and q e(exp) (297 mg/g), shows an underestimation of binding sites, suggesting the rate of reaction is not diffusion controlled and adsorption here cannot be classified as truly pseudo 1 st order. 67,70,71 Whereas, the adsorption capacity obtained from pK2 fitting q e = 259.4 mg/g is relatively closer to the true adsorption capacity at equilibrium (297 mg/g). The adsorption is driven by the pseudo 2 nd order kinetics and the rate limiting step in attaining the equilibrium is chemisorption involving the valence forces through the exchange of electrons between NNRG and U, complexation, coordination and/or chelation.…”

Section: Kinetics Of Uranium Adsorptionmentioning

confidence: 62%

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Polymer Nanorings with Uranium Specific Clefts for Selective Recovery of Uranium from Acidic Effluents via Reductive Adsorption

et al. 2020

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Nanostructured polymeric materials, functionalized with appropriate receptor have opened up newer possibilities for designing a reagent that shows analyte-specific recognition and efficient scavenging of an analyte that has either detrimental influence for human physiology and environment or for its recovery for further value addition. Higher active surface area, morphological diversity, synthetic tuneability for desired surface functionalization, and the ease of regeneration of nanostructured material for further use have provided such material with a distinct edge over conventional reagents. Use of biodegradable polymeric backbone has an added significance owing to the recent concern over the impact of polymer on the environment. Functionalization of biodegradable sodium alginate with AENA (6.85 % grafting) as the receptor functionality led to a unique open framework nanoring (NNRG) morphology with a favourable spatial orientation for specific recognition and efficient binding to uranyl ions (U) in an aqueous medium over a varied pH range. Nanoring morphology was confirmed by TEM and AFM images. The nano-scale design maximizes the surface area for the molecular scavenger. A combination of all these features along with the reversible binding phenomenon has made NNRG as a superior reagent for specific, efficient uptake of UO 2 2+ species from an acidic (pH 3-4) solution and compares better than all existing UO 2 2+-scavengers reported till date. This could be utilized for recovery of uranyl species from a synthetic acidic effluent of the nuclear power. Results of the U uptake experiments reveal a maximum adsorption capacity of 268 mg of U per g of NNRG in synthetic nuclear effluent. XPS studies revealed a reductive complexation process and stabilization of U(IV)-species in adsorbed uranium species (U@NNRG).

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Section: Isotherms For Uranium Adsorptionmentioning

confidence: 60%

Section: Kinetics Of Uranium Adsorptionmentioning

confidence: 62%

Polymer Nanorings with Uranium Specific Clefts for Selective Recovery of Uranium from Acidic Effluents via Reductive Adsorption

et al. 2020

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“…The binding isotherms were calculated using the SigmaPlot 12 (Systat Software Inc., Richmond, CA, USA). Non-linear least-square fitting was applied to the averaged experimental data, using a simple Langmuir isotherm model [21,22]:…”

Section: Equilibrium Batch Rebindingmentioning

confidence: 99%

Delayed Addition of Template Molecules Enhances the Binding Properties of Diclofenac-Imprinted Polymers

et al. 2020

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It has been reported that in the molecular imprinting technique, the use of preformed oligomers instead of functional monomers increases the stability of the non-covalent interactions with the template molecule, providing a sharp gain in terms of binding properties for the resulting imprinted polymer. Based on this theory, we assumed that the delayed addition of template molecules to a polymerization mixture enhances the binding properties of the resulting polymer. To verify this hypothesis, we imprinted several mixtures of 4-vinylpyridine/ethylene dimethacrylate (1:6 mol/mol) in acetonitrile by adding diclofenac progressively later from the beginning of the polymerization process. After polymerization, the binding isotherms of imprinted and non-imprinted materials were measured in acetonitrile by partition equilibrium experiments. Binding data confirm our hypothesis, as imprinted polymers prepared by delayed addition, with delay times of 5 and 10 min, showed higher binding affinity (Keq = 1.37 × 104 L mol−1 and 1.80 × 104 L mol−1) than the polymer obtained in the presence of template at the beginning (Keq = 5.30 × 103 L mol−1). Similarly, an increase in the imprinting factor measured vs. the non-imprinted polymer in the binding selectivity with respect to mefenamic acid was observed. We believe that the delayed addition approach could be useful in prepar imprinted polymers with higher binding affinity and increased binding selectivity in cases of difficult imprinting polymerization.

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“…Porous materials possess extensive interior for carrying out a wide variety of chemical processes in confined space. These include adsorption, [1][2][3] catalysis, [4][5][6] and ion transport, [7][8][9] during which the formation of new chemical bonds and the variation of intermolecular interactions constantly perturb the are responsive to even subtle changes in pore environment, making architectural damage a common cause of material deterioration in prolonged use.…”

Section: Introductionmentioning

confidence: 99%

Circumventing Wear and Tear of Adaptive Porous Materials

Canossa

Wuttke

2020

Adv Funct Materials

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The assessment of the architectural stability of molecular porous materials is not yet a common practice, but critical to their understanding and development. The conformational adaptation of porous materials to guest binding and other chemical dynamics poses a risk of architectural damage, leading to performance deterioration during their prolonged usage. The deformation of the framework backbone and the disconnection of building units are driven by chemical, mechanical, and thermal perturbations, and can be quantitatively described by the term connection completeness. Analytical means that can be used to measure this parameter are presented in order to provide a standard, practical protocol for evaluating architectural damage made to framework materials. Preventive and remedial strategies are proposed for enhancing the architectural integrity of frameworks without compromising their functional mechanisms, paving the way to the design of robust yet adaptive materials. In this way, the discussion on architectural stability is initiated, and readers are encouraged to carefully characterize molecular porous materials for a better understanding of their structure-property relationship.

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Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

Cited by 194 publications

References 112 publications

Polymer Nanorings with Uranium Specific Clefts for Selective Recovery of Uranium from Acidic Effluents via Reductive Adsorption

Polymer Nanorings with Uranium Specific Clefts for Selective Recovery of Uranium from Acidic Effluents via Reductive Adsorption

Delayed Addition of Template Molecules Enhances the Binding Properties of Diclofenac-Imprinted Polymers

Circumventing Wear and Tear of Adaptive Porous Materials

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