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A reduced graphene oxide (rGO) supported magnetite nanoparticle (nFe 3 O 4 ) composite (nFe 3 O 4 /rGO) was synthesized and shown for the first time to be an efficient persulfate activator to generate SO 4 − for trichloroethylene (TCE) degradation. The degradation efficiency of TCE (0.15 mmol L −1 ) was 98.6% within 5 min in the presence of 6.94 g L −1 nFe 3 O 4 /rGO with an optimum mass ratio of 1:4 and persulfate concentration of 3.0 mmol L −1 . By dispersing nFe 3 O 4 on the rGO surface, nanoparticle agglomeration was prevented and the aggregation of the rGO sheets was disrupted. Both the redox effect coupled in nFe 3 O 4 and the electron transfer by functional groups containing oxygen on the surface of rGO enhanced the SO 4 − generation. Given the identified free radical species and the characterization of the nFe 3 O 4 /rGO, a persulfate activation mechanism by nFe 3 O 4 /rGO for the degradation of TCE was interpreted. [ABSTRACT FROM AUTHOR]

The combination of surfactant enhanced soil washing and degradation of nitrobenzene (NB) in effluent with persulfate was investigated to remediate NB contaminated soil. Aqueous solution of sodium dodecylbenzenesulfonate (SDBS, 24.0 mmol L-1) was used at a given mass ratio of solution to soil (20:1) to extract NB contaminated soil (47.3 mg kg-1), resulting in NB desorption removal efficient of 76.8%. The washing effluent was treated in Fe2+/persulfate and Fe2+/H2O2 systems successively. The degradation removal of NB was 97.9%, being much higher than that of SDBS (51.6%) with addition of 40.0 mmol L-1 Fe2+ and 40.0 mmol L-1 persulfate after 15 min reaction. The preferential degradation was related to the lone pair electron of generated SO4•−, which preferably removes electrons from aromatic parts of NB over long alkyl chains of SDBS through hydrogen abstraction reactions. No preferential degradation was observed in •OH based oxidation because of its hydrogen abstraction or addition mechanism. The sustained SDBS could be reused for washing the contaminated soil. The combination of the effective surfactant-enhanced washing and the preferential degradation of NB with Fe2+/persulfate provide a useful option to remediate NB contaminated soil. [ABSTRACT FROM AUTHOR]

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15 mmol L −1 ) was 99.4% in the presence of nZVI/BC (4.5 mmol L −1 , nZVI to BC mass ratio was 1:5) and persulfate (4.5 mmol L −1 ) within 5 min, which was significantly higher than that (56.6%) in nZVI–persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO 4 - generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe 2+ /Fe 3+ (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO 4 - in nZVI/BC–persulfate system were clarified. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]