A novel hydrogen peroxide stabilizer in descaling process of metal surface

A recently developed descaling process for metal surface, which utilizes sulphuric, hydrofluoric acid and hydrogen peroxide (H2O2), has attracted great attention in consideration of eco-friendly sustainable process development. However, the intrinsic presence of metal ions, especially Fe(III), dramatically accelerates H2O2 decomposition, resulting in undesirable economic losses and even paralysis of operation. In this study, the stability of H2O2 in aqueous descaling acid was assessed by varying the ferric content from 0 to 30 g/L and the temperature from 32 to 45 °C. The results showed that any minor fluctuation in either factors causes a big attenuation in the life span of H2O2, necessitating the addition of a stabilizer. Thereby, a comprehensive screening test for potential stabilizers was carried out for an attempt to decelerate the H2O2 decomposition. Among all prospects, 2-anilinoethanol (AE, 100 mg/L) showed the most prominent stabilizing potential by successfully extending the half-life of peroxide by a factor of 2.66 compared to a controlled condition. The feasibility of AE as a stabilizer was further explored by elucidating its fate with GC-MS and IC analyses. A series of aromatics and short-chain organic acids was identified as the reaction intermediates. Aniline, with great H2O2 stabilizing capacity, was a predominant byproduct, which could help explain the superb positive effect of AE.