Abstract
ABSTRACT
In metal degreasing, aqueous alkaline solutions can often be substituted for organic solvents. Such water-based degreasing agents should be formulated so that associated negative impacts on occupational health and the environment are minimized. With these goals in mind, a review and an evaluation of chemicals utilization in water-based degreasing agents has been carried out. These include strongly alkaline agents, sodium metasilicate, complexing agents, corrosion inhibitors, surfactants, organic solvents, bactericides, coloring agents, and perfumes. In a shop test a water-based degreasing agent formulated in accordance with these criteria has been shown to be able to degrease aluminum parts contaminated with oils from a draw process to an acceptable quality of cleanness before burnishing. By recycling the degreasing agent in a microfiltration unit it was possible to increase the service life of the bath 5 times, and to reduce the use of chemicals such as the builder component to 20%, the surfactant component to 30%, and water utilization for setting up baths to 20%. Further, process down time has been decreased for emptying and setting up baths thereby also reducing the attendant occupational health and safety risks. There is a need for further tests of other degreasing agents formulated with the same criteria for additional metals and metal parts with different contamination and cleanliness standards. New developments in microfiltration units should also be exploited.
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