Interface quartz/water

Previously, we have proposed that SFG intensity due to interfacial water at quartz/ water interfaces reflects the number of oriented water molecules within the electric double layer and, in turn, the double layer thickness based on the p H dependence of the SFG intensity [10] and a linear relation between the SFG intensity and (ionic strength) [12]. In the case of the Pt/electrolyte solution interface the drop in the potential profile in the vicinity ofelectrode become precipitous as the electrode becomes more highly charged. Thus, the ordered water layer in the vicinity of the electrode surface becomes thiimer as the electrode is more highly charged. Since the number of ordered water molecules becomes smaller, the SFG intensity should become weaker at potentials away from the pzc. This is contrary to the experimental result. 

Du, Q., Freysz, E. and Shen, Y. R. (1994) Vibrational spectra of water molecules at quartz/water interfaces. Phys. Rev. Lett., 72, 238-241. 

Forciniti, D., and Hamilton, W. A. (2005). Surface enrichment of proteins at quartz/water interfaces a neutron reflectivity study. J. Col. Interface Sci. 285,458-468. 

Fig. 7.12 Heterogeneity of the H2O-VUV process generation of different reaction zones during 1 72 nm irradiation of water containing dissolved organic matter. Total oxygen depletion at the Suprasil quartz/water interface was...

The contact-free photoreactors include the vertical falling film design (Fig. 8-5), the inchned flat bed system (Fig. 8-6) and the batch photoreactor (Figs. 8-7 and 8-8). These reactor configurations do not have a quartz/water interface (as in situations A, B, C, Fig. 8-3), so that the problems related to fouling and film formation are effectively circumvented. Such photoreactor types are even suited for the UV treatment of suspensions and cloudy wastewaters (cf Kim and Thomanetz, 1995). 

The internal transmittance of quartz and Suprasil quartz is related to the thickness of the sample according to the Beer-Lamhert law, decreasing with increasing thickness of the quartz layer. Flow-through photoreactors (cf. Fig. 8-3) require quartz sleeves for lamp protection and hence suffer from radiation losses due to reflectance at the air (gas)/quartz and quartz/water interfaces (cf. Fig. 3-11). Reflection losses depend on the magnitude of the refraction index n and are usually in the range of about 7 to 8% for n=1.45 (Bolton, 1999, Braun et ah, 1991, Scaiano, 1989). Thus, a maximum transmittance T of quartz materials of 93% can be reached. The application of the Fresnel Law was demonstrated by Bolton (2000). 

During the design experiments, many observations regarding the future engineering concept can be gathered, for example, concerning the formation of inner filters or films on the quartz/water interface. 

Lin L-S, Johnston CT, Blatchley III ER (1999) Inorganic Fouling at Quartz Water Interfaces in Ultraviolet Photoreactors — II. Temporal and Spatial Distributions, Wat. 

Figure 3.14. Adsorption isothenn of 0104 at the quartz-water interface at pH 4 bulk solution. T = 300 K. ksnc = 290 nm. (From Mifflin et al., 2003 copyright 2003 American Chemical Society.)...

Mifflin, A. L., Gerth, K. A., and Geiger, F. M. (2003). Kinetics of cluomate adsorption and desorption at fused quartz/water interfaces studied by second hannonic generation. J. Phys. Chem. A 107, 9620-9627. 

Figure 14. Reflectivity functions for two double layer samples with different air/film (uppermost layer) surface roughness mimicking the type of layers in a GIXAS cell geometry. The high frequency oscillations are finite thickness oscillations due to the second 1 pm water layer. Substrate (quartz)/water and water/film interfaces have rms roughness = 0.0. X-ray energy is 7100 eV. The arrows indicate the approximate positions of the vacuum/material interface critical reflectivity angles for the different layer materials.

Figure 5.18. Volume fraction profiles obtained by neutron reflectivity for poly(ethylene oxide) adsorbed at the quartz/water interface. The vertical dashed line indicates the position of the quartz/water boundary. Dashed lines on the volume fiiaction curve show the limits of uncertainty at long distances from the boundary. After Lee et al. (1990).

Adeagbo, W.A., N.L. Doltsinis, K. Klevakina, and J. Renner, Transport processes at alpha-quartz-water interfaces Insights fix>m first-principles molecular dynamics simulations. Chem-physchem, 2008. 9(7) p. 994-1002. 

Fig. 4 Fresnel factors calculated for ssp- and sps-polarization at (a, c) fused quartz/air interface and (b, d) fused quartz/water interface, respectively, as function of incident angle for visible beam (ru is, 800 nm). The incident angle for IR beam (roiR, 3300 nm) is fixed at 50°.

There is a great interest in the nature of the interface between water and silicate minerals (see for example Davis and Hayes (1986)). Much of the chemical activity in soils, sediments and porous rocks occurs at such an interface. Experimentally, it is very difficult to examine this interface because it is such a small part of the liquid-solid system. Hydrated smectites and vermiculites have water between all of the silicate layers and therefore the percentage of the sample which is interface is enormously larger than the interface between, for example, a grsin of quartz in contact with liquid water. Another way to look at this is that the surface are of a quartz sand is probably much less than 1 m gram while a typical smectite has a surface area of as much as 800 m /gram. For these, and other reasons, intercalated clays have been extensively studied. 

The reports were that water condensed from the vapor phase into 10-100-/im quartz or pyrex capillaries had physical properties distinctly different from those of bulk liquid water. Confirmations came from a variety of laboratories around the world (see the August 1971 issue of Journal of Colloid Interface Science), and it was proposed that a new phase of water had been found many called this water polywater rather than the original Deijaguin term, anomalous water. There were confirming theoretical calculations (see Refs. 121, 122) Eventually, however, it was determined that the micro-amoimts of water that could be isolated from small capillaries was always contaminated by salts and other impurities leached from the walls. The nonexistence of anomalous or poly water as a new, pure phase of water was acknowledged in 1974 by Deijaguin and co-workers [123]. There is a mass of fascinating anecdotal history omitted here for lack of space but told very well by Frank [124]. 

Metal-solution interface, quantum mechanical calculations for (Kripsonsov), 174 Metal-water affinity, 177 Micro-balance, quartz crystal, 578 Microwave circuit, 446 for Faraday rotation, 454 Microwave conductivity... 

Quantum chemical calculations, 172 Quantum chemical method, calculations of the adsorption of water by, 172 Quantum mechanical calculations for the metal-solution interface (Kripsonsov), 174 and water adsorption, 76 Quartz crystal micro-balance, used for electronically conducting polymer formation, 578... 

Intetfacial Water Structure at Po/ywViy/ Alcohol (PVA) Gel/Quartz Interfaces 89... 

Interfacial Water Structure at Po/yw ny/ Alcohol (PVA) Cel/Quartz Interfaces 91... 

Although the total intensity of the SFG spectra decreased as the pressure on the PVA gel was increased, the intensity ratio between the peaks corresponding to icelike water and liquid-like water was almost constant. Since the OTS-modified quartz surface was hydrophobic, the water squeezed from the bulk gel was ice-like at the PVA gel/OTS-modified quartz interface. 

These results at the interfaces between the PVA gel and quartz surfaces, with and without modification by OTS, suggest that the weakly hydrogen bonded, that is, liquid-like , water plays an important role for the low friction at the PVA gel/quartz interface. 

The structure of water at the PVA/quartz interface was investigated by SFG spectroscopy. Two broad peaks were observed in the OH-stretching region at 3200 and 3400 cm , due to ice-like and liquid-like water, respectively, in both cases. The relative intensity of the SFG signal due to liquid-like water increased when the PVA gel was pressed against the quartz surface. No such increase of the liquid-like water was observed when the PVA gel was contacted to the hydro-phobic OTS-modified quartz surface where friction was high. These results suggest the important role of water structure for low friction at the polymer gel/solid interfaces. 

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