Filter aids diatomaceous earth

Caution The catalyst is ojten pyrophoric and should be kept moistened with alcohol. Celite is a diatomaceous earth filter aid. 

Procedure Prepare a 50% (w/w) sample solution in water. Adjust the pH to 7.0 0.2 with 1% sodium hydroxide or 1% hydrochloric acid. Filter through a 0.45-pim pore-size membrane filter, using a vacuum and a diatomaceous earth filter aid (1% on solids) if necessary. Discard the first portion of the filtrate if it is cloudy. Determine the density and concentration of solids, in grams per milliliters, refractometrically. Rinse the measuring cell three times with the sample solution, and then fill the cell. Measure absorbancy (As) at 420 nm Calculate the color in ICUMSA units (IU) as follows ... 

Again acidify the solution with Dowex 50 and filter as before. Neutralize the filtrate with calcium hydroxide and add enough excess to saturate the solution. Add 20 mg. of diatomaceous earth filter aid per liter of solution. In a fine sintered-glass filtering funnel, slurry 100 mg. of the filter aid per square centimeter of filter surface. Suck most of the water from the slurry through the funnel, but before the slurry is quite dry, filter the per bromate solution through it. Wash with saturated calcium hydroxide. 

Fig. 4. Hydraulic characteristics of various diatomaceous earth filter aids.

Diatomaceous earth filter aids are widely used in industrial filtration operations, and have evolved as an integral part in many other processes. Besides turbidities naturally occurring as a result of processing, diatomaceous earth filter aids are used to remove... 

CELITE Manville s registered trade name for its line of diatomaceous earth filter aids and fillers (5). 

Diatomaceous Earth Filter aids of diatomaceous earth have a dry bulk density of 128 to 320 kg/m (8 to 20 Ib/ft ), contain particles mostly smaller than 50 jxm, and produce a cake with porosity in the range of 0.9 (volume of voids/total filter-cake volume). The high porosity (compared with a porosity of 0.38 for randomly packed uniform spheres and 0.2 to 0.3 for a ical filter cake) is indicative of its filter-aid abihty. Different methods of processing the crude diatomite result in a series of filter aids having a wide range of permeability. 

An ammonium polysulfide solution is prepared as in Section 3-A above to this solution is added 3.00 g K2PdCl4 (9.18 mmole) dissolved in 10 mL water. After shaking for 2 minutes, the initial black precipitate redissolves, and the solution is filtered through diatomaceous earth (filter aid or Celite) prewashed with ammonium hydroxide. The filtrate is stoppered and the reaction allowed to proceed 5 days at room temperature (ca. 22°). At this time, the solution is noticeably lighter in color and the product has precipitated. After filtration, the complex is washed with water, ethanol, diethyl ether, carbon disulfide, and... 

Polarimetry (589 nm) White sugar do not require clarification Raw sugar, brown and yellow sugars addition of lead subacetate, along with a diatomaceous earth filter aid, with filtration to obtain a clear solution of little color. Subacetate can be replaced by an aluminum salt or ultrafiltration, but for raw cane sugar these reagents do not provide satisfactory clarification... 

The imreacted zircon and impurities can be removed, with diflBculty, by filtration and diatomaceous earth filter aids are beneficial. 

Concentrates containing up to 80 per cent uranium are first dissolved by nitric acid in stainless-steel, steam-heated, stirred vessels. The slurry is then fed to a bank of rotary vacuum filters where silica and small amounts of other insoluble impurities are removed. These filters are of the pre-coat type, the filter medium being a 2 in. layer of diatomaceous earth filter-aid, supported on cloth and removed to the extent of a few thousandths of an inch at each revolution. Washing takes place on the drum, the washings being mixed with the main filtrate to provide a clear hquor for TBP extraction at a uranium concentration of 300 g/1. and a free acidity of up to 3N. 

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