Different kinds of persulfate activation with base for the oxidation and mechanism of BDE209 in a spiked soil system

The feasibility of using base persulfate (PS) and coupled with other activation methods (heat, ultrasonic and Fe2+gluconate) was first explored for the removal of decabromodiphenyl ether (BDE209) in a soil system, and various factors were also investigated. The results showed that the removal of BDE209 followed a pseudo-first-order model. Interestingly, the rate constant (k1) indicated a good power exponential relationship with initial PS (k1=0.018×[PS]00.437, R2=0.983, [PS]0=0.02–0.5M) or BDE209 (k1=0.029×e−0.038×[BDE209]0, R2=0.999, [BDE209]0=10–50mgkg−1) concentration, respectively. Additionally, k1 well fitted the Arrhenius equation at the temperature range of 25 to 55°C, and the calculated activation energy (Ea) approximately was 41.2kJmol−1. The removal efficiency could be enhanced in the presence of ultrasound due to increasing the amount of BDE209 molecules desorbed from soil and organic matters. Finally, nine intermediate products were identified during the heat and base co-activated PS oxidation process, and the possible reaction pathways were further proposed. Conditions: [BDE209]0=20mgkg−1, [PS]0=0.2M, pH0=12.2, reaction time=360min. [Display omitted] •Effective oxidation of BDE209 was achieved by base and coupled with other activation of PS.•The removal of BDE209 followed a pseudo-first-order kinetics pattern.•Hydroxyl radical was identified as predominant oxidizing species.•Intermediate products during the heat and base co-activated PS oxidation were determined.•The potential reaction pathway and mechanism were proposed.