Diffusion mass load densities

Surface acoustic waves (SAW), which are sensitive to surface changes, are especially sensitive to mass loading and theoretically orders of magnitude more sensitive than bulk acoustic waves [43]. Adsorption of gas onto the device surface causes a perturbation in the propagation velocity of the surface acoustic wave, this effect can be used to observe very small changes in mass density of 10 g/cm (the film has to be deposited on a piezoelectric substrate). SAW device can be useful as sensors for vapour or solution species and as monitors for thin film properties such as diffusivity. They can be used for example as a mass sensor or microbalance to determine the adsorption isotherms of small thin film samples (only 0.2 cm of sample are required in the cell) [42]. 

Figure 12-4 displays the H2 density distribution obtained over the course of a simulation for the 1.51 wt. % and 6.5 wt. % H2 loadings. These distributions were obtained by determining the locations of the centers of mass of each H2 molecule at every MD step. In both cases, the calculated MD trajectories show that H2 molecules quickly diffuse around the exterior of the nanotube bundle. The adsorption process is highly dynamic on the exterior walls of the bundle. While molecules at the... 

We know that solubility of the solute(s) can be directly correlated to solvent density, as can diffusivity of the solute into and through the solvent.Typically, solubility increases with density, while diffusivity decreases. Density is strictly a function of temperature and pressure. Similarly, mass transfer increases with reduced solvent viscosity and increasing agitation t l generally, viscosity increases with temperature for a supercritical fluid.The rate of solvation is dependent on the concentrations of both the solvent and solute and the density and temperature of the solvent. Concentration is fixed by flow rate, solvent volume, and contaminant loading. Thus,... 

A load of solvent is spilled over a large area, resulting in a layer of liquid with an area density of 1 kg/m. The solvent has a vapor pressure of 10 kPa and an average molar mass of 100. Diffusivity is estimated at 10" m /s. Calculate the time of evaporation in the absence of any air currents. This is tire maximum to be expected. 

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