CHEM-BANK

Not all the cyanide that is absorbed by the body undergoes oxygen inhibition. It is known that 80% of the absorbed cyanide is detoxified in the liver by the enzyme mitochondrial rhodanase. The enzyme catalyzes the transfer of a sulfur atom to combine with the cyanide to form the less toxic thiocyanate, which is excreted in the urine. In high exposures to cyanide, the sulfur donors are rapidly depleted and cyanide metaboUsm is slowed (Pope and Rail, 1995). The half-life for the conversion of cyanide to thiocyanate from a nonlethal dose in humans is between 20 and 60 minutes (CHEM-BANK, 1999). 

In normal, healthy human organs, cyanide is present at concentrations ranging up to 0.5 mg/kg (CHEM-BANK, 1999) and the relative proportion of thiocyanate to cyanide in body fluids is about 1,000 1. Normal plasma thiocyanate levels are 0.01 mg/mL for both smokers and non-smokers. Lethal values of thiocyanates range from 0.05 to 0.2 mg/mL (Pope and Rail, 1995). Smokers are included in the data because heavy smoking increases the urinary concentrations of thiocyanate levels and can be misleading for cyanide exposure (Corn, 1993). 

Source Kirk-Othmer, 1979a Ullmann s, 1987 CHEM-BANK, 1999. 

CHEM-BANK. 1999. Sodium Cyanide, SUverPlatter Health Safety Publishing, Norwood, MA (CD-ROM). 

CHEM-BANK includes five important data banks with topics on chemical safety IRIS, RTTCS, HSDB, OHMTADS, and CHRIS. 

For turbulent flow through shallow tube banks, the average friction factor per row will be somewhat greater than indicated by Figs. 6-42 and 6-43, which are based on 10 or more rows depth. A 30 percent increase per row for 2 rows, 15 percent per row lor 3 rows and 7 percent per row for 4 rows can be taken as the maximum likely to be encountered (Boucher and Lapple, Chem. Eng. Prog., 44, 117—134 [1948]). 

For laminar flow of non-Newtouiau fluids across tube banks, see Adams and Bell Chem. Eng. Prog., 64, Symp. Ser, 82, 133-145 [1968]). 

For sieve trays, Chan and Fair [Ind. Eng. Chem. Pioc. Des. Dev., 23, 814 (1983)] used a data bank of larger-scale distillation column efficiencies to deduce the following expression for the product kcCi ... 

The method for estimating point efficiency, outhned here, is not the only approach available for sieve plates, and more mechanistic methods are under development. For example, Prado and Fair [Ind. Eng. Chem. Re.s., 29, 1031 (1990)] have proposed a method whereby bubbling and jetting are taken into account however the method has not been vahdated tor nonaqueous systems. Chen and Chuang [Ind. Eng. Chem. Re.s., 32, 701 (1993)] have proposed a more mechanistic model for predicting point efficiency, but it needs evaluation against a commercial scale distillation data bank. One can expect more development in this area of plate efficiency prediction. 

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