Improvements in Waste Minimization, Process Safety, and Running Costs by Integrated Process Development

Abstract

By the development of a new recycling process for spent acid in the manufacture of the 1-chloro-2,4-dinitrobenzene (CDNB) effective improvements in the waste balance and the process safety were achieved. Under the old process, the sulfuric acid generated could not be sold to the low strength sulfuric-acid market, because it had a high concentration of organic contaminants. The resulting waste stream had long been a costly issue. A laboratory feasibility study followed by pilot evaluation qualified continuous extraction as an appropriate technology for purifying the acid. With the change from a batch extraction process to a continuous extraction on a column, the quality of the acid could be improved such that use without further regeneration is possible now. Thus, the continuous extraction column offered improved efficiency, safety, and product consistency as compared to the corresponding batch process.