Filtration of corrosive liquids

Filtration of corrosive liquids with suction. A strongly alkaline or acid suspension is best filtered through a sintered glass funnel. Alternatively, glass wool or asbestos may be plugged into the stem of a glass funnel or supported upon a Witt plate in a glass funnel. 

Benzylatnine. Warm an alcoholic suspension of 118-5 g. of finely-powdered benzyl phthalimide with 25 g. of 100 per cent, hydrazine hydrate (CAUTION corrosive liquid) a white, gelatinous precipitate is produced rapidly. Decompose the latter (when its formation appears complete) by heating with excess of hydrochloric acid on a steam bath. Collect the phthalyl hydrazide which separates by suction filtration, and wash it with a little water. Concentrate the filtrate by distillation to remove alcohol, cool, filter from the small amount of precipitated phthalyl hydrazide, render alkaline with excess of sodium hydroxide solution, and extract the liberated benzylamine with ether. Dry the ethereal solution with potassium hydroxide pellets, remove the solvent (compare Fig. //, 13, 4) on a water bath and finally distil the residue. Collect the benzylamine at 185-187° the 3ueld is 50 g. 

The open cell structure of carbon foam with its greater than 90% porosity and chemical inertness at temperatures below 500°C suggests its use as a filtration media for corrosive liquids and a dispersant for gases. 

An important application field for stainless steel fibers is the textile sector, in which 0., i to 6% of these fibers are incorporated to endow carpets, protective clothing etc. with an antistatic finish. A further application is protection against electromagnetic pulses, interference and charging. Tungsten fibers with a diameter of 12 pm are used for boron or SiC deposition and as light bulb filaments. Furthermore, metal fibers are used in the filtration of polymer melts and corrosive liquids, as well as for electrodes with high surface areas. 

In industrial filtration a common filter medium is canvas cloth, either duck or twill weave. Many different weights and patterns of weave are available for different services. Corrosive liquids require the use of other filter media, such as woolen cloth, metal cloth of monel or stainless steel, glass cloth, or paper. Synthetic fabrics like nylon, polypropylene, and various polyesters are also highly resistant chemically. 

Chemicaiiy-Resistant Fibers. Fibers with excellent chemical resistance to corrosive and/or chemical warfare agents or extreme pH conditions (eg, very acidic or very alkaline) were initially used for protective clothing. However, applications for filtration of gases and liquids in numerous industrial facilities are now more important. For example, PPS is suitable for use in filter fabrics for coal-fired boilers because of its outstanding chemical and heat resistance to acidic flue gases and its excellent durability imder these end use conditions. Many high tenacity fibers are also chemically inert or relatively unaffected under a variety of conditions. Aramids, gel spun polyethylene, polypropylene, fluorocarbon, and carbon fibers meet these criteria and have been used or are being considered for applications where chemical resistance is important. 

Another purpose of removing ionic species from the water or coolant loop is to maintain the desirable low ionic conductivity of these fluids to avoid shunt current, which is an internal short current (ionic) and also accelerates local corrosion. Typically, a bypass filtration loop through a deionizing (demineralizing) filter is used to continuously clean up a portion of the liquid. Replacement or regeneration of the ion filter or other filters is necessary to ensure the effectiveness of those filters. 

Filtration Principles and Practices Second Edition, edited by Michael J. Matteson and Clyde Orr Corrosion Mechanisms, edited by Florian Mansfeld Catalysis and Surface Properties of Liquid Metals and Alloys, Yoshisada Ogino... 

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