Diatomaceous bleaching earth

FIGURE 7.10 Surface concentrations and their intensity distributions for (A) the acidic and (B) the basic sites of adsorbents used in frying oil. A, activated carbon B, alumina (basic) C, alumina (neutral) D, alumina (acidic) E, bleaching earth F, diatomaceous earth G, silica and H, magnesium silicate. 

Filtration Equipment Good filtration equipment and proper operation are essential if the filtration process is to be effective and economical. Modem-day bleaching earths should not, except in rare cases, require the use of filter aids such as diatomaceous earth. Rather, the clay is used as the precoat. According to Veldkamp (123), the two main objectives in precoat filtration are as follows ... 

Next, the refined oil is bleached (reacted with activated clays, diatomaceous earths, or recoverable silicas) to adsorb phospholipids, color pigments, soaps, peroxides, aldehydes, and other polar compounds, and is recovered by filtration. Spent bleaching earths in the filter cake contain pigments, occasional residual pesticides, aldehydes, and other compounds removed from the oil, and they often present disposal problems. 

Small areas Puddles of liquid can be absorbed by covering with absorbent material such as vermiculite, diatomaceous earth, clay, sponges, or towels. Place the absorbed material into containers lined with high-density polyethylene. Wash the area with copious amounts of soap and water or undiluted household bleach (see Section 16.5.3.1). If bleach is used, then rewash the area with soap and water. Collect and containerize the rinseate in containers lined with high-density polyethylene. 

The military also identifies the following "nonstandard" decontaminants Detrochlorite (thickened bleach mixture of diatomaceous earth, anionic wetting agent, calcium hypochlorite, and water), 3% aqueous peracetic acid solution, 1% aqueous hyamine solution, and a 10% aqueous sodium or potassium hydroxide solution. 

Bleaching is carried out under a vacuum of 20-25 mmHg and at a temperature of 95-110°C with retention time of 30-45 min (47). The slurry containing the oil and earth is then filtered to recover a clear, light orange color pretreated oil. Usually a small amount of diatomaceous earth is used to precoat the filter leaves to improve the filtration process. As a quality precaution, the filtered oil is polished through another security filter bag in series, to trap any earth particles that escape through the first filter. This is essential as the presence of spent earth particles in the pretreated oil reduces the oxidative stability of the final RBD oil (46). The spent... 

Small Areas Puddles of liquid must be contained by covering with vermiculite, diatomaceous earth, clay, fine sand, sponges, paper towels or cloth towels. Place the absorbed material into containers with a high-density polyethylene liner. Decontaminate the area with a fresh solution of HTH pool bleach in denatured alcohol (approximately 9 percent by weight) followed by decontamination with copious amounts of aqueous sodium hydroxide solution (a minimum of 10 percent by weight). Vigorous off-gassing may... 

For direct saponification routes to soap, once a fat blend has been selected then particularly for toilet soap formulations, some method of raw material pretreatment is often applied. Commonly used methods involve bleaching, either with diatomaceous earth or activated carbon and, less commonly, deodorization... 

Bleach Filtration. The discussion of brine treatment in Section 7.5 covered the characteristics of the particles formed by chemical precipitation and the types of filter used to remove them. As that discussion would indicate, the particles found in bleach solutions are not easy to filter. Filter aids are necessary, and pressure-leaf filters are commonly used. Figure 15.17 shows a typical skid-mounted unit. Pumps and bleach filter bodies and plates should be titanium. Nonmetallic components are PVC or PTFE. Other components of the system (e.g., filter aid tanks) may be FRP. Filter aids should be diatomaceous earth or Perlite (Section 7.5.4.2). 

The wax is harvested by removing the honey and melting the comb in hot water. Further purification is done by filtration or centrifugation. B. is yellow and can be bleached by sunlight or diatomaceous earth to a white wax. 

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