An ultra-efficient pretreatment method adopted LPUV/CoFe2O4/PMS-based photolysis for accurate detection of Cd(II) and Pb(II) in water via SWASV.

• The influences of humus on the electroactivity of Cd(II) and Pb(II) were studied. • A LPUV/CoFe 2 O 4 /PMS-based pretreatment method was proposed for HMIs detection. • The effect of key pretreatment parameters on HMIs signal recovery was explored. • The roles of LPUV and CoFe 2 O 4 for signal recovery were determined. • The recovery mechanism of the SWASV signal was systematically investigated. Dissolved organic matter (DOM) is a widely occurring substance in rivers that can strongly complex with heavy metal ions (HMIs), severely interfering with the electrochemical signal of anodic stripping voltammetry (ASV) and reducing the detection accuracy of HMIs in water. In this study, we investigated a novel advanced oxidation process (AOP) that involves the activation of peroxymonosulfate (PMS) using low-pressure ultraviolet (LPUV) radiation and CoFe 2 O 4 photocatalysis. This novel AOP was used for the first time as an effective pretreatment method to break or weaken the complexation between HMIs and DOM, thereby restoring the electrochemical signals of HMIs. The key parameters, including the PMS concentration, CoFe 2 O 4 concentration, and photolysis time, were optimized to be 6 mg/L, 12 mg/L, and 30 s for eliminating DOM interference during the electrochemical analysis of HMIs via LPUV/CoFe 2 O 4 -based photolysis. Investigations of the microstructure, surface morphology, specific surface area, and pore volume of CoFe 2 O 4 were conducted to reveal the exceptional signal recovery capability of LPUV/CoFe 2 O 4 /PMS-based photolysis in mitigating interference from DOM during HMIs analysis. The PMS activation mechanism, which is critical to the signal recovery process, was elucidated by analyzing the reactive oxygen species (ROS) and the surface elemental composition of CoFe 2 O 4. Additionally, the degradation and transformation behavior of humus-HMIs complexes were analyzed to study the mechanism of ASV signal recovery further. Notably, the detection results of HMIs in actual water samples obtained using the proposed pretreatment method were compared with those obtained from ICP-MS, yielding an RMSE less than 0.04 μg/L, which indicated the satisfactory performance of the proposed pretreatment method for the ASV detection of HMIs in complex actual samples. [Display omitted] [ABSTRACT FROM AUTHOR]