Removal of organic micropollutants from water by sonophotolytic-activated persulfate process

The present study focuses on the improvement of the efficiency of water treatment by coupling irradiation with ultraviolet (UV) light-emitting diodes and high-frequency ultrasound (US) for activation of persulfate (PS). Organic micropollutants (atrazine, bisphenol A and carbamazepine) were sequentially treated in aqueous solution at non-adjusted pH and initial concentration of 20 μM in a batch sonophotoreactor. The hybrid oxidation system (UV/US/PS) showed the highest efficiency (≥90%) for removing bisphenol A and carbamazepine within 40 min of treatment, whereas atrazine was degraded with comparable rates under UV/PS and UV/US/PS processes. In terms of removal efficiency, the applied systems for bisphenol A and carbamazepine can be arranged as follows: UV/US/PS > UV/PS > US/PS > UV/US ≈ UV ≈ US. Overall, the hybrid sonophotolytic method using high-frequency US appears to be a promising technique to activate PS for eliminating organic micropollutants from aqueous media. (paper)