Mineral Acid Purification Opportunities
Abstract
Extending the life of mineral acid baths is environmentally and economically attractive. There are technologies currently available that can offer these benefits. Two such technologies are diffusion dialysis and acid Sorption. These two competing technologies were objectively evaluated using bench scale equipment to compare their ability to remove metal contaminants and recover free acid from a contaminated mineral acid bath. This comparison provides some criteria for evaluation of each technology when applied to the recovery of hydrochloric acid (HCI) from iron (Fe) contaminated hydrochloric acid solutions. The solutions prepared in the laboratory for these tests closely approximate actual spent hydrochloric acid activation and cleaning baths. While the results indicate that both technologies are effective in recovering free acid and removing iron from the test solutions, there are distinct differences between the two. The diffusion dialysis system achieved acid recoveries averaging 97% and iron rejection averaging 86%. Acid sorption achieved acid recovery and iron removal efficiencies of approximately 96% and 45%, respectively. Conclusions for diffusion dialysis are: * the diffusion dialysis system has a higher HCI recovery efficiency per gram of acid fed to it, but because of the degree of osmosis occurring within the membrane stack during these tests, the diffusate acid concentration is approximately 55 - 60% of the feed acid concentration, * the diffusion dialysis system achieves greater percent rejection of the contaminant metal in the feed; approximately 52% higher than acid sorption in this case (osmosis acts to increase metal rejection) * fresh make up acid will be required when processing a work tank with a diffusion dialysis system (quantity will be dependent on system performance and the ability to minimize osmosis),
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1996
- Accession Number
- ADP017698
Entities
People
- David S. Roberts
- Wayne A. Kinnel
Organizations
- Concurrent Technologies Corporation