Phosphotungstic Acid to Remarkably Enhance Fe(III)/peroxymonosulfate for the Ultrafast Removal of Organic Pollutants

The heterogeneous photocatalyst could effectively enhance Fe(III)- activated peroxymonosulfate (PMS) to remove organic pollutants in wastewater, however, the homogeneous photocatalyst is little reported so far. In this work, the removal of organic pollutants in the Fe(III)/PMS system was developed under the both darkness and LED illumination, by the addition of phosphotungstic acid (HPW) as homogeneous photocatalyst. Important influencing factors were optimized in the both darkness and LED illumination, including Fe(III), PMS and HPW concentrations, and extra anions. The results showed that Rhodamine B removal by Fe(III)/PMS was significantly strengthened after introducing HPW. In addition, it maintained a wide pH range. The mechanism studies revealed that HPW enhancing Fe(III)/PMS achieved the physical behavior in the darkness, whereas the existence of radical and non-radical pathways were primarily contributed for removing organic pollutants by HPW boosting PMS under LED illumination. The different approaches could be easily achieved by simply switching between darkness and LED illumination. This study provided a new process for treating organic pollutants in wastewater.