A dual-oxidant compounding technology based on calcium peroxide and persulfate for polycyclic aromatic hydrocarbons removal in soil

Polycyclic aromatic hydrocarbons (PAHs) pollution in soil is a serious threat to ecology and human health, so it is necessary to develop green and sustainable remediation technology. In this study, a dual-oxidant compounding reagent containing sodium persulfate (Na 2 S 2 O 8 ) and calcium peroxide (CaO 2 ) were developed, and iron (II) ferrous sulfate heptahydrate (FeSO 4 ∙7H 2 O) and potassium citrate monohydrate (K 3 C 6 H 5 O 7 ) were used as activator and chelating agent, respectively, to explore the removal efficiency of PAHs with different molecular weights in soil. It was found that when the concentration of persulfate ion (S 2 O 8 2− ) was 0.2 mol∙kg −1 , CaO 2 dosage was 20 g∙kg −1 , Fe 2+ /S 2 O 8 2− ratio was 1/2, Fe 2+ /C 6 H 5 O 7 3− ratio was 1/2, and soil-water ratio was 1:1, the removal percentage of total PAHs was 73.90%, and were 47.41%, 69.00% and 78.05% for LMW-PAHs, MMW-PAHs, and HMW-PAHs, respectively. The response surface methodology (RSM) was used to further optimize the reaction conditions. A dual-oxidant reagent package (1 kg) containing 125 g CaO 2 , 176 g FeSO 4 ∙7H 2 O, 297 g Na 2 S 2 O 8 , and 406 g K 3 C 6 H 5 O 7 was prepared. Under normal temperature and neutral pH, this dual-oxidant reagent package was applied to farmland soil and reacted for 2 d, the removal percentage of total PAHs (1208.77 μg∙kg −1 ) in soil was 47.23%, and was 79.01% for HMW-PAHs. Then a new integrated fertilization-attenuation-growth promotion technology was developed, which can remove PAHs and maintain soil fertility. The total PAHs can be removed effectively by this integrated technology, and vegetables could be safely grown in the soil after remediation. This study provides theoretical support for the development new PAHs-contaminated soil remediation technology, and also provides a reference for the safe production of crops. • A CaO 2 -persulfate dual-oxidant compounding reagent package was prepared. • Removal percentage of PAHs with different molecular weights was as high as 74%. • The effects of different factors on the removal of PAHs were investigated. • RSM optimization for PAHs removal by dual-oxidant compounding reagent were determined. • A new fertilization-attenuation-promotion technology was developed.