The Oxidative Immobilization Of Phosphonate By Simulated Solar Light Mediated Peroxi-Coagulation Process Sustained By The Iron-Air Fuel Cell

Phosphonates are an important type of phosphorus-containing compounds and is of primary concern due to its eutrophication potential. Herein, we achieved simultaneously oxidative immobilization of phosphorus from ethylene diamine tetra (methylene phosphonic acid) (EDTMP) in the simulated solar light mediated peroxicoagulation process sustained by the iron-air fuel cell (IAFC). The integration of simulated solar light irradiation with IAFC could enhance the oxidation capacity, yield of iron ions and power density output. The highest total phosphorus (TP) removal efficiency (approximately 100%) could be obtained at pH 4.0 owing to the synergistic action of coprecipitation and oxidation of EDTMP to orthophosphate (o-PO4), accompanying the optimum power density of 2459 mW m- 2 at 2086 mA m- 2. The center dot OH mediated oxidation and photodegradation of Fe(III)-EDTMP complex via ligand-to-metal charge transfer reaction worked together to transform EDTMP into oPO4. In the precipitate, the immobilized phosphorus existed mainly in the forms of organic phosphorus and oPO4. The presence of oxalic and citric acid enhanced the yield of center dot OH, but the formation of soluble Fe(III)carboxylate complexes negatively affected the TP removal due to the decreased precipitation capacity. Contrastly, the observed decrease in TP removal caused by humic acid was ascribed to its scavenging effect toward center dot OH. In general, this study proposed an energy efficient and environmental friendly approach for mitigating the potential risk of phosphonates to environmental safety.