Quantitative analysis of iron residue in potassium hydroxide: A time-dependent study

Iron (Fe) contamination in potassium hydroxide (KOH) poses a significant challenge for the reliability of membrane based alkaline electrolysis systems (AEMWE) due to its influence on electrocatalytic behaviour and system stability. The dissolution of Fe from cell components or as an electrolyte impurity can affect membrane resistivity, produce short circuit pathways, and result in anomalous deposition within the system. The objective of this study is to compare various benchmark purification methods and develop a simple, effective, and accelerated protocol for Fe removal using a 3 electrode Pt-mesh setup. Fe residues in KOH were quantified using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) over a 24-h pre-electrolysis period. The results indicated that Fe levels dropped significantly within the first two hours of pre-electrolysis. By combining acid washing and holding at open-circuit potential (OCP) in Fe-free KOH, Pt mesh was shown to be capable of reducing Fe levels in contaminated KOH solutions to near-zero levels within 2 h. • Pre-electrolysis protocol reduces Fe in KOH to near zero levels in under 2 h. • Pt mesh is an effective and highly reusable electrode for purifying KOH. • Iron deposits onto Pt rapidly within the first 30 min of pre-electrolysis.