Hydrogen peroxide decomposition in an environmentally friendly pickling solution for AISI 316L stainless steel

Abstract

There is increasing interest in the utilization of ecological bath solutions for the pickling of stainless steel (SS), because conventional nitric (HNO3) and hydrofluoric (HF) acid mixtures generate high NOx emissions. A mixture of hydrogen peroxide (H 2O2), sulfuric acid (H2SO 4), and HF has been tested in this study as an environmentally friendly pickling solution for AISI 316L SS (UNS S31603 . The decomposition of H2O2 and the H 2SO4-HF-H2O2 mixture was assessed at different temperatures from 25°C to 60°C, with ferric ion contents from 0 to 40 g/L, with and without stirring of the aqueous acid mixture. Me p-Toluene sulfonic, 3-hydroxybenzoic, and 4-dodecylbenzene sulfonic acids were tested as stabilizers for H 2O2. The AISI 316L SS pickling rate found at 50°C was 2.35 × 103 mg/dm2-day (mdd) and 0.12 × 103 mdd, respectively, in the absence and presence of 40 g/L ferric ion. © 2005, NACE International.