Pore clogging

Existing statistical methods permit prediction of macroscopic results of the processes without complete description of the microscopic phenomena. They are helpful in establishing the hydrodynamic relations of liquid flow through porous bodies, the evaluation of filtration quality with pore clogging, description of particle distributions and in obtaining geometrical parameters of random layers of solid particles. 

Nonwoven filter media are mostly used for filter medium filtration with pore clogging. Because of the relatively low cost of this medium, it is often replaced after pore clogging. In some cases, nonwoven media are used for cake filtration. In this case, cake removal is so difficult that it must be removed altogether from the filter medium. Nonwoven filter media can be prepared so that pore sizes decrease in the direction from the surface of the filter media contacting suspension to the surface contacting the supporting device. This decreases the hydraulic resistance of... 

Salicylic acid is used to treat acne, warts, dandruff, psoriasis, and similar conditions. In the treatment of acne, it slows the shedding of skin cells in hair follicles, so they do not clog the pores and cause pimples. It also has a keratolytic effect—it causes dead skin cells to slough off— which removes the top layer of skin and clears existing pore clogs. 

Anaerobic processes are less likely to produce pore-clogging biomass and... 

At a given pore size of the support a certain minimum concentration is necessary to obtain a gel layer, otherwise pore clogging will occur. With an increase in the sol concentration the casting rate increases. Typical concentrations used are from 0.7-1.2 mol AlOOH/L (see (5) below). 

Pad conditioning serves to reverse the pore-clogging process, and there are two general approaches that seek to apply any of several pad-conditioning methods. One approach consists of concurrent pad conditioning. In this... 

The pore clogging period is shortened when the concentration of solids is increased [5] and with larger (secondary) particle size. If the concentration and/or the particle size is large enough, pore clogging hardly occurs and a gel film is immediately formed. 

Glycolic acid (8%) softens the skin, prevents pores clogging up, stimulates epidermal turnover (pH 4)... 

Tangential Flow Hundreds of Manufacturing scale May High viscosity or pore clogging ... 

To overcome such limitations, Imura et al. covered the surface of a silica gel with sulfonated cross-linked polystyrene [5]. After adsorption of styrene, divinyl-benzene, and r-butyl peroxide and subsequent free-radical polymerization, the acid groups are introduced via classical sulfonation. Control of the thickness of the crosslinked polymer layer on the surface is essential to prevent pore clogging. This sulfonated polystyrene-Si02 hybrid material preserves a large specific surface area, with a typical ion-exchange capacity of 1.8 meq g. Alternatively, a sulfonated layer can be deposited on silica by copolymerization of silica-supported methacrylate and potassium p-styrene sulfonate [6]. 

Particle sizing by filtration was unsuccessful because of pore clogging of the Nuclepore membrane. Results of filtration experiments confirm the results of work cited previously and lead to two major conclusions (1) vacuum membrane filtration is not an acceptable means of particle sizing and (2) membranes with pore sizes of 1 /xm or less should be used for suspended-solids analysis. 

Catalyst particle with pores clogged with polymer... 

Metallic filter media may be used either for cake filtration or depth filtration, i.e., pore clogging. Regeneration of media may be achieved by dissolving solid particles inside the pores or by back thrust of filtrate. 

To prevent pore clogging in the filter medium when handling relatively low solids concentrations (e.g., 0.1-1% by volume), general practice is to increase the solids concentration in thickeners before the suspension is fed to the filter. 

Acne is a common disorder with important psychosocial effects. It occurs in predisposed individuals when sebum production increases. Proliferation of the microorganism Propionibacterium acnes in the sebum alters it and causes pore clogging. Lesions are noninflammatory (comedones, also known as blackheads and whiteheads) or inflammatory (papules, pustules, or nodules). The extent and severity of the lesions varies, from a few comedones to the strongly inflammatory acne conglobata. 

A slight decrease in solvent flux was also observed after 50 h of continuous operation at transmembrane pressure of 0.5 bar. This observation can be explained by the internal pore clogging and external surface fouling due to insoluble iron oxide/hydroxide precipitation that reduced the pore size of the membrane. Such phenomena have been extensively studied and reported in the literature (Tansel et al., 2000). Taking into account the adverse effects on the permeation property that occurred for long duration of membrane operation, the Hagen-Poiseuille equation is written as follow ... 

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