Purpose To comply with the effluent regulation of boron, replacement of boric acid with citric acid in a nickel electroplating bath is proposed. Although the bath avoids the discharge of boron, it increases the discharge of nickel owing to the chelating effect of citric acid, which disturbs the wastewater treatment. To balance this trade-off, the environmental impacts of a traditional nickel plating process (the Watts bath) and the citrate bath must be compared by life cycle assessment. Methods The life cycle impact assessment method was LIME2. To estimate the trade-off between boron and nickel discharge into wastewater, the characterization and damage factors on human toxicity and ecotoxicity were calculated. The processes were then compared using data from actual processes. The functional unit was Bplating per 1-kg part.Ĥ owever, the plating efficiency depends on the type, shape, and surface area of the part. The data of the citrate bath were modeled. In the modeling, the amounts of nickel chloride and nickel sulfate in the citrate bath were based on the Watts bath. Results and discussion In comparison with other chemicals, the calculated characterization and damage factors of boron and nickel were found to be reasonable. The integration results revealed that the citrate bath exerted greater environmental impact than the Watts bath. Although the Watts bath involved more environmentally damaging processes than the citrate bath, the sum of these impacts was much smaller than the impact of effluent from the citrate bath. Moreover, the environmental impact of effluent can be significantly reduced by flocculants, with almost no additional environmental impact incurred by the increased sludge. Conclusions The newly developed citrate plating bath exerts higher environmental impact than the traditional Watts bath because the environmental impacts of the release of nickel chelated with citric acid exceed the reduced boron emissions. Therefore, there is a trade-off between the two methods. When installing the citrate bath, the wastewater treatment must be altered to reduce the nickel emissions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.