Hang Cui,Xiaogang Gu,Shuguang Lu,Xiaori Fu,Xiang Zhang,George Y. Fu,Zhaofu Qiu,Qian Sui
Ethylbenzene (EB) degradation performance in (S,S)-ethylenediamine-N,N-disuccinic acid (EDDS) chelated Fe(III) activated sodium percarbonate (SPC) system was investigated in this study. The effects of various factors, such as the dosages of SPC and Fe(III), molar ratio of EDDS/Fe(III), anions (Cl − , HCO 3 − , SO 4 2− , and NO 3 − ) concentration, natural organic matters (NOM), and initial solution pH were evaluated. The results showed that the addition of EDDS remarkably improved the EB removal in Fe(III)/SPC system. Both HCO 3 − anions and NOM had significantly inhibitive effect, while the influence of SO 4 2− , Cl − and NO 3 − could be negligible on EB degradation. The EB removal was inhibited at extremely low and high initial solution pH. Moreover, the results of free radical probe tests, scavenger tests and electron paramagnetic resonance (EPR) detection indicated that OH was the predominant species responsible for EB degradation even though both OH and O 2 − were generated in the SPC/EDDS–Fe(III) system. The oxidation products were analyzed and possible EB degradation pathways were proposed. In conclusion, this study provides an important insight into the application of SPC/EDDS–Fe(III) system in the removal of EB contaminant, especially for in situ remediation of BTEX-contaminated groundwater.
CuMgFe layered double hydroxide (CuMgFe-LDH) was successfully synthesized and characterized as an efficient catalyst of persulfate (PS) for the degradation of ethylbenzene. Under the conditions of 0.2 g L −1 CuMgFe-LDH and 4.0 mmol L −1 persulfate at pH 7.6, the degradation efficiency of 0.08 mmol L −1 ethylbenzene was 93.7% with TOC removal efficiency of 65.2% in 24 h, and the concentration of Cu leached into the solution was as low as 0.095 mg L −1 after the reaction. The reuse of CuMgFe-LDH showed that the catalyst was highly stable after 5 recycles. Electron Spin Resonance (ESR) test and free radical quenching experiment indicated that SO 4 − and OH radicals were the dominant species accounted for the degradation of ethylbenzene in the CuMgFe-LDH/persulfate system. Catalytic mechanism of the formation of a complex of Cu(II) O 3 SOOSO 3 2− and the subsequent redox cycle of Cu(II)/Cu(III) accounted for the generation of radicals was proposed.
A high catalytic system using Cu layered double hydrotalcite (Cu(II)-Mg(II)-Fe(III)LDHs) and hydrogen peroxide (H 2 O 2 ) was developed for the degradation of ethylbenzene. It was identified that the degradation efficiency of ethylbenzene (0.08 mmol L −1 ) and TOC removal were 96.1% and 39.7% respectively in the presence of 0.1 g L −1 Cu(II)-Mg(II)-Fe(III)LDHs with (Cu 2+ + Mg 2+ )/Fe 3+ molar ratio of 5.0 and 0.16 mmol L −1 H 2 O 2 in 6.0 h. Based on ESR and XPS data, hydroxyl radicals (•OH) were the predominant free radical specials generated from the catalytic decomposition of H 2 O 2 for the degradation of ethylbenzene. The redox of Cu(II)/Cu(III) on the layered Cu(II)-Mg(II)-Fe(III)LDHs surface active sites accounted for the formation of •OH radicals and the cycle of Cu(II) in the Cu(II)-Mg(II)-Fe(III)LDHs/H 2 O 2 system were proposed.
危险品化学品经营许可证（带存储）