Effective degradation of organophosphorus pesticide by photo-Fenton and in-situ recovery/utilization of the generated phosphorus: Dual function of iron ions.

• Organophosphorus pesticides degradation and in-situ phosphate recovery system was constructed. • The degradation efficiency of trichlorfon in this system surpassed 98% • Phosphorus from the degradation process was recovered in the form of vivianite with the overall recovery rate of 85.1%. • In this system, the toxicity of degradation byproduct was lower than trichlorfon, and iron in the photo-Fenton system is also recovered. • The recovered vivianite has great potential for water treatment. Efficient recovery and utilization of the generated phosphorus during the process of organophosphorus pesticides degradation is promising but still challenging. In this study, a photo-Fenton-crystallization sequential processes were developed to achieve the degradation of organophosphorus pesticides and simultaneous recovery/utilization of the generated phosphate. In this system, iron ions exhibited dual functionality: activator of the photo-Fenton reaction and crystallizing agent of the generated phosphate and the crystals obtained were proved to be vivianite by X-ray Diffraction and Scanning Electron Microscopy. The results showed that a trichlorfon degradation rate exceeding 90% and a vivianite yield of 85.1% was achieved. Parameters such as pH and the Fe-P ratio play pivotal roles in phosphorus recovery efficiency from wastewater. In addition, the toxicity of the degradation by-products was much less than that of trichlorfon by the Toxicity Estimation Software Tool. Additionally, the recovered vivianite exhibits advantageous catalytic properties to activate peroxymonosulfate for the degradation of different pollutants. This study provides a novel perspective for the treatment and utilization of organophosphorus pesticides. [ABSTRACT FROM AUTHOR]