Electrochemical detection of Hg(II) in complexed soil samples using an innovative pretreatment approach based on oxygen vacancy-rich ZnCo2O4 nanocages membrane and peroxymonosulfate activation

Accurate detection of Hg(II) in soil is critical due to their severe environmental and heath risks. However, interference from soil organic matter, particularly humic acid (HA), complicates electrochemical detection by forming stable complexes with Hg(II), suppressing signal in square wave anodic stripping voltammetry (SWASV). This study introduces a novel pretreatment method using oxygen vacancy-rich ZnCo 2 O 4 nanocages (OVs-ZnCo 2 O 4 HNCs) to activate peroxymonosulfate (PMS) and generate sulfate radicals (·SO 4 − ). These radicals disrupt HA-Hg(II) complexes, restoring Hg(II) to its free, electroactive state for accurate detection. Optimized parameters, including ZnCo 2 O 4 loading (9 mg), PMS concentration (6 mg/L), and activation pH (3), enabled maximum signal recovery within 1.5 min. Comprehensive characterization confirmed the efficient catalytic activity of OVs-ZnCo 2 O 4 HNCs. The method demonstrated high sensitivity (LOD = 0.27 μg/L) and robustness in real soil samples, highlighting its potential for environmental monitoring and heavy metal analysis.