Study On The Efficacy And Mechanism Of Different Forms Of Iron-activated Persulfate Degradation Of Organophosphorus Flame Retardant Triphenyl Phosphate In Water

Triphenyl phosphate?TPhP?is a kind of organophosphorus flame retardant and is often used as a fire retardant additive or plasticizer.TPhP is widely used and con-stantly detected in different environmental media,and its environmental risks have gradually attracted people's attention.It has been found that TPhP has neurotoxicity,carcinogenicity,and developmental toxicity.However,TPhP can not be effectively removed in the sewage treatment process,so it is needed to develop the effective and economical treatment technology to eliminate TPhP in the water environment.Hydroxyl radicals?HO·?and sulfate radicals?SO₄·^-?with high oxidation poten-tial generated in advanced oxidation processes?AOPs?can degrade various organic pollutants.Compared with HO·,SO₄·^-based AOPs is more selective and can be ap-plied in a wide pH range.In addition,SO₄·^-has a longer half-life that is more condu-cive to the degradation of contaminants.Therefore,this paper used SO₄·^-based AOPs to degrade TPhP in water environment by different forms of iro n-activated persulfate.The effects and mechanisms of ferrous ions(Fe²⁺)activated potassium persulfate?PS?and cobalt ferrite?CoFe₂O₄?activated monopotassium peroxydissulfate?PMS?to d e-grade TPhP were investigated.Main research contents and results are as follows:?1?In the experiment of Fe²⁺activated PS degradation of TPhP,the effects of cat-alyst concentration,oxidant concentration,initial pH value,anions and humic acids?HA?on the degradation of TPhP in water environment were studied.The results showed that the removal of TPhP increased with the increase of catalyst and oxidant dosage;pH value?4-9?had little effect on the degradation of TPhP;HA promoted TPhP degradation.Anions?Cl^-and NO₃^-?were not significantly inhibited TPhP de g-radation.However,the effect of HCO₃^-on the degradation of TPhP is related to co n-centration.In addition,the removal of TPhP in various natural water matrices was studied to better understand the feasibility of AOPs to eliminate TPhP from natural water.Lower TPhP removal in these aqueous matrices indicated that a high oxidant dose and/or long reaction time was required to achieve efficient removal and high mineralization.Free radical quenching experiments and electron paramagnetic res o-nance?EPR?spectroscopy analys is showed that SO₄·^-radicals were responsible for the degradation of TPhP in the Fe²⁺/PS process.The degradation products of TPhP were identified by LC-MS/MS technology,and the possible transformation pathway was proposed accordingly.?2?In the experiment of CoFe₂O₄ activated PMS degradation of TPhP,the effects of PMS and CoFe₂O₄,initial pH,HA and anions?Cl^-,NO₃^-and HCO₃^-?on the degra-dation of TPhP were systematically studied.The results showed that the degradation of TPhP decreased with the increase of CoFe₂O₄ dose,and the degradation of TPhP in-creased with the increase of PMS concentration.The optimal pH value of TPhP de g-radation was 7.0.HA(2-20 mg L^-1),which is a representative organic natural sub-stance present in the environment,inhibited the removal of TPhP.The anions of Cl^-,NO₃^-and HCO₃^-inhibited the degradation of TPhP.Free radical identification experi-ments show that SO₄·^-is the main radical in TPhP degradation.In addition,the trans-formation products of TPhP were identified by LC-MS technology,and the possible transformation pathway of TPhP was proposed.