OXIDATION PERFORMANCE OF NITRILOTRIS(METHYLENE PHOSPHONIC ACID)BY POTASSIUM PERMANGANATE
Organic pollutants could be degraded by KMnO4,and the oxidation process of phosphonates by KMnO4 is still unclear.Herein,using nitrilotris(methylene phosphonic acid,NTMP)as a model pollutant,radical capture experiments and electron paramagnetic resonance(EPR)were used to explore the dominant active oxidizing species in KMnO4 system,and the effects of solution chemical properties(such as pH,coexisting substances,actual water body,etc.)on the degradation of NTMP by KMnO4 were investigated.The results showed that direct oxidation of KMnO4 was the dominant pathway for NTMP degradation,and its degradation was greatly influenced by pH value.The best oxidation performance of NTMP by KMnO4 was obtained at pH=5.0,and 51.4％of NTMP was oxidized into PO4,much higher than that in UV/H2O2 and UV/potassium persulfate(PDS)system.No obvious inhibition on the degradation of NTMP was observed in the presence of coexisting substances in water(i.e.,SO4-,NO3,HCO3,and humic acid).In addition,KMnO4 also showed a high degradation efficiency on NTMP in actual wastewater,and its selectivity was better than that of free radical systems.The results provide an important reference for the efficient removal of phosphonates from actual wastewater.
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