Kinetics of Vapour Diffusion and Condensation in Natural Porous Cellulosic Fibre Web

Abstract

Vapour diffusion in a porous web material followed by its absorption or condensation is a typical process for all porous materials particularly on polymeric and natural basis. The description of kinetic weight increment increase during this process was proposed by use of a relatively simple function with adequately defined theoretical background. It was shown that this kinetic process is controlled by vapour diffusion through porous web material. This tool in connection with observations at different air relative humidity and with use of relatively simple technique enables one to evaluate the structure properties and its structure homogeneity, that is, the uniformity character of the porous stratified web material. Utilization of this description was demonstrated during moistening kinetics of paper web of different composition from primary and secondary fibres on lignocellulosic and only cellulosic basis with different ash content.

Cellulosic Sorption Filter Materials with Surface Flocculation Activity—A Hopeful Anticipation of Water Purification

“…This behaviour is similar as the kinetics of vapour diffusion and condensation in porous cellulosic fibre web formation, e.g. paper [19]. Therefore, it is possible to conclude that the adsorption process does not take place strictly on the surface of oxycellulose but instead is followed by diffusion to a limited depth of its cell-wall.…”

Mutual Competitive Absorption of Water and Essential Oils Molecules by Porose Ligno-Cellulosic Materials

“…with an increase of EO absorption a relative diffusivity of its molecules decrease independent of all other factors. Logically, an increasing of absorption retards the diffusivity of molecules [4]. As indicated Figure 3, an absorption capacity of water vapour for all pulp sorts is increased exponentially with increase of relative air humidity being influenced in small extent by pulp quality and presence of EO molecules.…”

“…Typical for paper and similar ligno-cellulosic materials is a porous non-oriented hypermolecular structure. Due to this structure and hydrophilic surface-molecular character of pore interface, ability to humidification with characteristic water vapour absorption kinetic [4] is typical for these materials. A lot of biomaterials applications especially a tremendous potential for biomedical applications and drug delivery systems are connected with water vapour and other liquid vapour absorption [5] [6].…”

“…Generally, vapour absorption of water and other liquids in porous materials is given by their microstructure and hypermolecular properties. It was shown [4] that the kinetics of important practical absorption vapour processes as vapour condensation and moistening of porous web material can be described using of relative simple function.…”

Modeling of Water Generation from Air Using Anhydrous Salts

“…Based on a kinetic process that is controlled by the vapor diffusion through the porous material, depending on the relative humidity, we can analyze and estimate the absorption rates and the rates of release of water vapor from the anhydrous salts. In this paper work, the model developed by Cesek et al [51] was considered, which originally was used to describe vapor absorption in porous cellulosic fiber web. The one-dimensional diffusion of molecules in the perpendicular direction of the porous material into thin layer (Figure 2) is described by Fick's first law as: From Figure 1A, following the system concept, the water vapor diffuses into the anhydrous salt layer (the adsorbent layer), filling the pores of the adsorbent, when the fan is on, allowing the air to flow through the adsorbent layer.…”