Hydrodynamic cavitation activation of persulfate for the degradation of polycyclic aromatic hydrocarbons in marine sediments

Abstract

Hydrodynamic cavitation (HC) coupled with persulfate (PS)-based that resulted in the synergistic degradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated marine sediments. The effects of HC injection pressure and Σ[PAH]: [PS] on the rate and extent of PAH degradation were studied in the pressure range of 0.5–2.0 bar, PS concentration rage of 2 × 10−4 to 2 × 10−2 M or Σ[PAH]: [PS] of 1:10–1000, and reaction time of 20–60 min. A pseudo-first-order rate law fitted PAHs removal kinetics well. The degradation rate constant increased with injection pressure, reaching the maximum level at 0.5 bar, then decreased at injection pressure became greater than 0.5 bar. The results showed that PAH removal was 84% by the combined HC and PS process, whereas, HC alone only achieved a 43% removal of PAHs in marine sediments under the optimal inlet pressure of 0.5 bar at PS concentration of 2 × 10−2 M in 60 min. The HC‒PS system effectively removed PH, PY, FLU, BaA, and CH at 91, 99, 91, 84, and 90%, respectively. The maximum removal of 6-, 5-, 4-, 3-, and 2-ring PAHs was 89, 87, 84, 76, and 34%, respectively. Major reactive oxygen species (ROSs), namely, SO4−• and HO•, were responsible for PAHs degradation. Results clearly highlighted the feasibility of HC−PS system for the clean-up of PAHs-laden sediments in particular and other recalcitrant organic contaminants in general.