Experimental study of high-voltage pulse blasting-electrokinetic method for remediation of Cr, Cd and pyrene...

Soil co-contaminated with organic pollutants like pyrene and heavy metals present significant challenges for remediation. Existing technologies are generally ineffective at simultaneously removing both types of contaminants. This study proposes a novel approach-high-voltage pulsed blasting (HVPB) coupled with electrokinetic remediation (EKR)-for the treatment of soil co-contaminated with Cr, Cd and pyrene. Laboratory-scale experiments were conducted to evaluate the removal efficiency and underlying mechanisms of this method. HVPB generated strong oxidizing species, including ·OH and O₃, which effectively degraded pyrene. Under conditions of 40 kV discharge voltage, 7 cm electrode spacing, and 10 % soil moisture content, pyrene degradation efficiency reached 76.1 % after 33 discharges. Moreover, HVPB fractured soil particles and enlarged their specific surface area, exposing contaminants trapped within soil lattices to pore water or particle surfaces. HVPB also facilitated the oxidation of immobile Cr(III) into the more mobile Cr(VI), thereby increasing the proportion of exchangeable heavy metals. After 7 h of EKR with prior HVPB treatment (2 V/cm voltage gradient, 0.5 mol/L acetic acid as the electrolyte, and EKG electrodes), the removal efficiencies of Cr(VI), Cr(III), and Cd reached 96.4 %, 87.0 %, and 70.2 %, respectively. Compared with conventional enhanced EKR, this approach markedly shortened treatment time, reduced energy consumption, and improved removal efficiency. The proposed HVPB-EKR method provides an efficient and low-carbon strategy for the rapid remediation of soil co-contaminated with PHAs and heavy metals.