Filter paper, surface area

If the filter s surface area is known, the straight line giving the volume filtered during a normal industrial filtration cycle may be plotted on logarithmic paper from two or three experimental... 

An important characteristic of solvents is rate of evaporation. Rates of solvent loss are controUed by the vapor pressure of the solvent(s) and temperature, partial pressure of the solvent over the surface, and thus the air-flow rate over the surface, and the ratio of surface area to volume. Tables of relative evaporation rates, in which -butyl acetate is the standard, are widely used in selecting solvents. These relative rates are deterrnined experimentally by comparing the times required to evaporate 90% of a weighed amount of solvent from filter paper under standard conditions as compared to the time for -butyl acetate. The rates are dependent on the standard conditions selected (6). Most tables of relative evaporation rates are said to be at 25°C. This, however, means that the air temperature was 25°C, not that the temperature of the evaporating solvent was 25°C. As solvents evaporate, temperature drops and the drop in temperature is greatest for solvents that evaporate most rapidly. 

Surface filters, if manufactured from the correct material, will not be affected by water in the oil. Water-resistant pleated-paper elements have much greater surface areas than the depth-type element and yield a much lower differential pressure when used as replacement elements in filters originally equipped with depth-type elements. Pleated-paper elements are available that will remove particle sizes down to a nominal one-half micron. 

The filter elements should remove particles of five microns, must be water-resistant, have a high flow rate capability with low pressure drop, possess high dirt-retention capacity, and be rupture-resistant. The clean pressure drop should not exceed five psig at 100 °F (38 °C). The elements must have a minimum collapse differential pressure of 50 psig. Pleated-paper elements are preferred—provided they meet these requirements. Usually, the pleated-paper element will yield the five psig clean drop when used in a filter that was sized to use depth-type elements. This result is due to the greater surface area of the pleated element, more than twice the area of a conventional stacked disc-type or other depth-type elements. 

Filtrier-erde, /. filtering earth. -flMche, /. filtering surface or area, -flasche, /. filtering flask, -gestell, n. filter stand, -hut, m. (paper) filtering funnel, -kessel, m. filtering boiler, -konus, m. filter cone, -korb, m. filtering basket, -nutsche, /. suction filter, -papier, n. filter paper, -papierstreifen, m. strip of filter paper, -platte, /. filter plate, -presse, /. filter press, -pumpe, /. filter... 

Some training in origami is de rigueur for chemists. It seems that the regular filter paper fold is inefficient, since very little of the paper is exposed. The idea here is to flute or corrugate the paper, increasing the surface area in contact with your filtrate. You ll have to do this several times to get good at it. 

The full potential use of biofilters for cleaning air from livestock buildings, treatment plants and emissions from chemical industry have yet to be exploited. The papers presented produced proof of the efficiency of these filters to remove odour emissions from odorous air streams. Research and Development work is required to reduce the costs of construction and to find materials to which will not deteriorate quickly. Work is required to reduce the large surface areas required at present. 

Approximately 7% of electric power in the United States goes into electrolytic chemical production. The electrolysis apparatus pictured here consists of a sheet of A1 foil taped or cemented to a wood surface. Any size will work, but an area about 15 cm on a side is convenient for a classroom demonstration. Tape to the metal foil (at one edge only) a sandwich consisting of filter paper,... 

Half an hour should be sufficient time for extraction offlavonol glycosides because of the high surface area of powdered material and the large volume of solvent. Another method of extraction is to add solvent to the sample in two to three aliquots, decant each through Whatman no. 1 filter paper at the end of a specified time, and combine the filtrates. 

Another possibility is the volatilisation of 210Po from soil or vegetation. In the laboratory, polonium is notorious for its ability to transfer from one surface to another. Abe Abe (1969) found that 60% of 210Po collected on a filter paper volatilised on heating to 200°C for one hour. The inventory of 210Po in topsoil is about 5000 times the inventory in air, when both are expressed per unit area of ground, so only a small degree of volatilisation or resuspension would materially increase the concentration in air. 

This filter paper is fragile when wet and must be supported. Glass filter paper has a high diffusion ratio giving an even flow throughout the filter matrix under negative pressure. An adequate flow rate is achieved with one hole 0.8 mm in diameter for an area 6 mm and a negative pressure of 15 psi (83 kN/m ). Under these conditions the precipitate is spread evenly over the surface of the Alter. 

Permeability-molecular surface area-in vitro-in silico model The permeability values obtained from the Caco-2 cell monolayers have been traditionally used to devise in silico models for the prediction of drug absorption. In this paper, the use of molecular surface areas as descriptors of permeability and solubility will be reviewed. Moreover, a virtual filter for the prediction of oral drug developability based on the successful combination of in vitro and in silico models of drug permeability and aqueous drug solubility will be discussed. 

Figure 1. Water uptake and changes in relative surface areas of Whatman / filter paper as a function of relative humidity. The adsorbates are n-decane (O) and mesitylene The numbers beside the points indicate the order of the...

The filter can consist of up to three elements. The outer element is a particulate filter, often made of glass fibre paper, pleated to increase surface area. The inner element is a vapour adsorbent, usually activated granular charcoal. The third element comprises various chemicals impregnated on to the charcoal, such as copper, chromium, silver and triethylenediamine (TEDA), to react with volatile chemical agents such as hydrogen cyanide and cyanogen chloride that are poorly adsorbed. 

---