Xuqian Wang,Wendan Zheng,Wenhua Tong,Aimin Zhang,Yongkui Zhang,Yabo Wang
Organophosphorus esters (OPEs) are important chemicals functioning as extractants, plasticizers, flame retardants, solvents, additives, etc., and are also recognized as hazardous organic liquids generated from industrial processes. Herein, we developed a CeO2-catalyzed degradation with simultaneous phosphorus immobilization technology to treat typical OPE solvents. Under the investigated reaction conditions of a temperature of 180 °C, a reaction time of 3 h, and a dosage of ball-milled CeO2 of 19.8 g mL–1 of the OPE, the model pollutant of tributyl phosphate (TBP) was efficiently degraded with phosphorus immobilization efficiency near 100%. Meanwhile, the mineralization efficiency of TBP was also as high as 98%, which was reflected by the chemical oxygen demand change of liquid products. Gaseous products generated from CeO2-catalyzed TBP degradation could also fulfill the requirements of an environmental standard. Further mechanism studies indicated that the surface oxygen vacancy in CeO2 induced the in situ formation of superoxide radicals, which dominated TBP degradation. During catalytic degradation, the P-containing species were mainly immobilized as cerium phosphate, while the hydrocarbon chains of TBP were degraded into small molecules and finally mineralized into inorganic species. The developed CeO2-catalyzed OPE degradation approach was also applicable to aromatic and halogenated OPEs, i.e., tricresyl phosphate and tris(2-chloroethyl) phosphate. This study provided a possible alternative for waste treatment of the waste of OPEs with low environmental risks.
He Liu,Jiahao Liang,Xiaodong Du,Rui Wang,Ting Tang,Xueqin Tao,Hua Yin,Zhi Dang,Guining Lu
Organophosphorus esters (OPEs), one kind of the emerging contaminants with high frequency of detection, is rather refractory in natural environment, thus posing great threat to human health. This study investigated the feasibility and mechanism of tris(2-chloroethyl) phosphate (TCEP) degradation in thermally activated persulfate (TAP) system. Influence of impact factors, such as PDS dosage, temperature, initial pH, and presence of natural water matrix (Cl − , NO 3 − , H 2 PO 4 − , NH 4 + , humic acid), were evaluated. Results showed that 100% degradation of TCEP can be achieved in TAP system in 40 min at 60 °C. SO 4 ·− as the dominant oxidant for TCEP degradation was proved by quenching experiment and verified by EPR analysis. Alkaline condition exerted great inhibitory effect by affecting the constituents of oxidative radicals. It is suggested that Cl − and H 2 PO 4 − at lower dosages promoted the degradation by stimulating ·OH production and forming oxidative radicals with better selectivity . Intermediates identified by high resolution mass spectrometer was suggested less toxic than TCEP by ECOSAR program. Meanwhile, the illustrated oxidation mechanism mainly involved radical attack at C Cl bond and cleavage of C O bond, as further confirmed by frontier electron density calculation and wavefunction analysis. Moreover, cyclic degradation of TCEP indicated the constant release of SO 4 ·− in 450 min, suggesting high efficiency and stability of PDS in TAP system. Four selected OPEs achieved complete removal in TAP system and their degradation discrepancy was further discussed based on the distinctive structures. Altogether, TAP technology can be used as an efficient method in TCEP removal with great potential for application.
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