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Something you might want to consider is that production of NaOH is tied to the production of elemental chlorine, and predictions are that the demand for chlorine will remain flat over the next several years while the demand for sodium hydroxide will rise (Chemical Marketing Reporter, vol 243, no 14, April 1993).  It's counterintuitive, but this means that the demand for sodium hydroxide may drive the production and use of chlorine.  Low prices for chlorine don't encourage efficient use.  Neutralized caustic isn't much of an environmental burden but inefficient use of chlorine, especially in the chlorinated organic compound chain, is.  

Chlorine and NaOH are mostly produced using diaphragm cells these days.  In the bad old days, production of these compounds resulted in a lot of releases of mercury.

Hydrogen chloride is partially produced from elemental chlorine but the vast majority of it is recovered from processes where chlorinated compounds are converted to non-chlorinated compounds and HCl is released.  

Kirsten Sinclair Rosselot, P.E.
Process Profiles
P.O. Box 8264
Calabasas, CA 91372-8264



On 06/14/99 10:41:28 you wrote:
>At Sandia National Laboratories (SNL), we are working with our 
>Microelectronics Development Laboratory, to reduce their water consumption 
>and waste production. (This is a joint effort between the P2 and water 
>conservation groups at SNL). One of the opportunities we are investigating 
>is replacing the cation and anion resins (used to produce the ultra-pure 
>water they require) with an Electro Deionization (EDI) process. EDI is a 
>combination of ion exchange and electro dialysis technologies, in which 
>cations and anions are continuously separated and removed from the water. 
>It eliminates the need to regenerate the resins with concentrated acid or 
>base (50%) solutions. This is currently done on-site, so replacement with 
>EDI would also eliminate a sodium hydroxide and hydrochloric acid storage 
>tank, associated piping and controls and safety hazards. The cost savings, 
>based on water, wastewater, chemicals and reduced labor, however, are 
>modest. (P/B ~ 5 years). We are in process of quantifying ancillary 
>benefits (i.e. safety, TRI reporting requirement).
>We would also like to consider global life-cycle impacts of eliminating 
>sodium hydroxide and hydrochloric acid use to justify the project. Does 
>anyone have information on the environmental burden (and cost, if possible) 
>of producing sodium hydroxide and hydrochloric acid (water use, energy use, 
>waste production, air emissions, etc.) ?
>Jack Mizner 
>SNL Pollution Prevention 
>(505) 845-3576