Diffusion Dialysis and Acid Recovery in Metal Operations. 2001.
TURI Technical Report No. 49
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File Synopsis: Acid baths are used within the electronics and metalworking and plating industries for a variety of metal etching and stripping processes. The bath removes unwanted substances such as metals from a product. These substances are then trapped within the bath usually in a dissolved state. With each use, the concentration of the contaminants increases. Once the contamination level reaches a point in which the bath is no longer functional for meeting process specifications, the bath is considered spent. The spent bath is then disposed, and fresh acid and possibly other additives are mixed together to create a new bath for processing. The spent bath containing several types of dissolved metals and other contaminants is then shipped off-site for treatment or treated on-site creating solid and liquid waste. The liquid waste is neutralized and released with discharge water, while the solid waste is sent for disposal or reprocessing. Innovative technologies are available for recycling a spent bath for reuse in order to provide for an increase in bath life. One of these technologies uses the concept of diffusion dialysis through anion exchange membranes, which is the method investigated in this research. Download file...