NMR studies of water adsorbed on a number of silica surfaces

Pearson, R.T.; Derbyshire, W.

doi:10.1016/0021-9797(74)90007-1

Cited by 73 publications

(45 citation statements)

References 45 publications

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“…The precise thickness of this layer appears to be temperature dependent (Webber et al, 2007a;Liu et al, 2006;Petrov et al, 2007). This surface layer was observed and studied for both water (Hansen et al, 1996b;Jehng et al, 1996;Pearson and Derbyshire, 1974) for an echo time 2τ = 2 ms. In both graphs the calibration pore diameter was determined by nitrogen gas adsorption.…”

Section: Calibrationmentioning

confidence: 95%

Nuclear magnetic resonance cryoporometry

2008

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Nuclear Magnetic Resonance (NMR) cryoporometry is a technique for non-destructively determining pore size distributions in porous media through the observation of the depressed melting point of a confined liquid. It is suitable for measuring pore diameters in the range 2 nm -1 µm, depending on the absorbate. Whilst NMR cryoporometry is a pertabative measurement, the results are independent of spin interactions at the pore surface and so can offer direct measurements of pore volume as a function of pore diameter. Pore size distributions obtained with NMR cryoporometry have been shown to compare favourably with those from other methods such as gas adsorption, DSC thermoporosimetry, and SANS. The applications of NMR cryoporometry include studies of silica gels, bones, cements, rocks and many other porous materials. It is also possible to adapt the basic experiment to provide structural resolution in spatially dependent pore size distributions, or behavioural information about the confined liquid.

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Section: Calibrationmentioning

confidence: 95%

Nuclear magnetic resonance cryoporometry

2008

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“…the ratio of average pore length to thickness of the penetrated layer and a factor that allows for both tortuosity and varying type of hysteresis have been discussed by many authors with pore cross sections (44). The average value of q 2 for the various models (9,34,35,39,41), such as the hysteresis five sets of data on porous Vycor glass has been reported in T 2 may represent a supercooling and superheating in the as 5.9 (44), so q Å 2.43. The curve in Fig.…”

Section: Nmr Linewidthmentioning

confidence: 98%

Studies of Water Adsorbed in Porous Vycor Glass

Hirama¹,

Takahashi²,

Hino³

et al. 1996

Journal of Colloid and Interface Science

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“…4) the separate peaks of two independent phases of internal water are present at room temperature and they do not vanish when resin is heated up to 60 °C. The slow exchange between the phases in silica-gel was also observed by Pearson and Derbyshire (7). …”

Section: Discussionmentioning

confidence: 54%

Pulsed NMR study of thermal hysteresis in the swollen macroreticular and gel-type resins

Narȩbska¹,

Streich²

1980

Colloid Polymer Sci

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In the study of gel-water systems with the stationary and pulsed NMR method a thermal hysteresis in the proton signals and relaxation times were observed by a few authors. This phenomenon draws an attention, as it seems, to the accompanying sol-gel transition in polymer solution or it may counterpart the phase transition of water in gels below 0 °C.Woessner and Co.(1) studied the agar-water system and stated a pronounced hysteresis in spin-spin relaxation time at the temperature interval from 30 °C up to 100 °C. The same system and phenomenon were discussed by Palrna (2) on the ground of the hysteresis in signal line width and T1/T 2 ratio. The suggestion of Palma is that thermal hysteresis indicates the cooperative behaviour of polymer and water molecules. "The sol-gel transition is macromolecule-controlled but the structural information is carried by water molecules".Another mechanism is responsible for the hysteretic phenomena observed at the temperature range below 0 °C. Until now this phenomenon was observed on porous silica-gels and also on gels of polyethylene glycol (3) and collagen (4).Barnes (5), Morariu, and Mills (6), Pearson and Derbyshire (7) studied silica-gels and stressed the following experimental results: -hysteresis is not observed when the water coverage corresponds to one layer, -hysteresis appeares only if the diameters of pores in silica are in the range Of hundred of angstroms and it is absent when the size of pores corresponds to few diameters of a water molecule.The authors find the possible sources for the hysteresis in: movement of the solid-liquid boundary closer to silica surface as water progressively freezes (Morariu and Mills), in the disturbance of adsorption equilibrium by freezing of water on surface causing unfrozen water molecules move from pores to surface where pressure is lower and whereupon they freeze (Barnes) or in supercooling and superheating occurring with water of enhanced structural ordering inside the filled pores (Pearson and Derbyshire). The results of Mank (8) and Bie~kiewicz (4) add more information concerning the thermal hysteresis, observed in natural or synthetic polymers, however, there is no agreement as to the mechanism involved.In this publication we present data on low temperature hysteresis of T 2 time and FID (free induction decay) found in macropormls ion exchange resins of different porous structures. For comparison, the measurements performed with the gel-type (nonporous) ion exchange resins have also been presented.The spin-echo technique was applied. The macroporous resins have also been investigated by Doskocilova (10) and Frankel (11, 12) with the high resolution NMR method. Experimental MaterialsThree macroreticular (also called macroporous) cation exchange resins: Amberlyst 15, Amberlite 200, Amberlite 252 (R6hm and Haas Co., Philadelphia, USA) and four geltype cation exchange resins: Zerolit 225 X1, X4-5, X20 M67

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NMR studies of water adsorbed on a number of silica surfaces

Cited by 73 publications

References 45 publications

Nuclear magnetic resonance cryoporometry

Nuclear magnetic resonance cryoporometry

Studies of Water Adsorbed in Porous Vycor Glass

Pulsed NMR study of thermal hysteresis in the swollen macroreticular and gel-type resins

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