• Clean Technology
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• v.11 no.1
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• pp.21-28
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• 2005

Nitric acid free pickling solution was applied to solve the severe environmental problems attributed to nitric acid during pickling process of stainless steel product. In points of pickling capability and erosion of stainless steel base metal, a solution contains I% of hydrochloric acid and 2% of hydrofluoric acid and hydrogen peroxide was revealed as the best alternative to conventional mixed acid of nitric acid and hydrofluoric acid. To keep the pickling capability, it was necessary to maintain the concentration ratio of hydrogen peroxide to hydrochloric acid above 0.5.