Efficient remediation of PAHs contaminated site soil using the novel slow-release oxidant material

Abstract

The eco-friendly slow-release material for persulfate (PS) using chitosan (CS) and urea (U) composite as frame structure (CS-U@PS) was firstly used to remediate the site soil contaminated by polycyclic aromatic hydrocarbons (PAHs) from Hefei city, China. The influences of glutaraldehyde dosage and urea dosage on the slow released properties of CS-U@PS was investigated and a longer release time of 190.0 d to 591.0 d was achieved, indicating the promising tunability according to the contents of pollutants in site soil. The effects of various factors (cross-linking agent dosage, initial PAHs concentration, CS-U@PS dosage, hydrogen peroxide dosage, etc.) on the degradation of soil spiked with PAHs (80 and 8 mg·kg−1) by CS-U@PS were studied, and the degradation pathway of PAHs was speculated. According to the EPR results, urea played an important role in promoting the 1O2 generation, which was the main reactive oxidative species. Finally, the long-term remediation of the industrial site soil with total PAHs of 553.2 mg·kg−1 was performed using 50 mg·g−1soil CS-U@PS and 90.22% removal rate was obtained after nine months. Moreover, the monitoring results of soil respiration gas show that, in addition to CO2, there is no additional greenhouse gas generated in the process of soil remediation, suggesting that the remediation of site soil using CS-U@PS has an excellent application prospect.