The destruction of benzene by calcium peroxide activated with Fe(II) in water

Abstract

The ability of Fe(II)-activated calcium peroxide (CaO2) to remove benzene is examined with a series of batch experiments. The results showed that benzene concentrations were reduced by 20 to 100% within 30 min. The magnitude of removal was dependent on the CaO2/Fe(II)/Benzene molar ratio, with much greater destruction observed for ratios of 4/4/1 or greater. An empirical equation was developed to quantify the destruction rate dependence on reagent composition. The presence of oxidative hydroxyl radicals (HO•) and reductive radicals (primarily O2•−) was identified by probe compound testing and electron paramagnetic resonance (EPR) tests. The results of the EPR tests indicated that the application of CaO2/Fe(II) enabled the radical intensity to remain steady for a relatively long time. The effect of initial solution pH was also investigated, and CaO2/Fe(II) enabled benzene removal over a wide pH range of 3.0~9.0. The results of radical scavenging tests showed that benzene removal occurred primarily by HO• oxidation in the CaO2/Fe(II) system, although reductive radicals also contributed. The intermediates in benzene destruction were identified to be phenol and biphenyl. The results indicate that Fe(II)-activated CaO2 is a feasible approach for treatment of benzene in contaminated groundwater remediation.

Generation of hydroxyl radicals by Fe-polyphenol-activated CaO2 as a potential treatment for soil-borne diseases

“…In addition, the hydroxyl radicals generated by the modified Fenton system using the Fe-CPP catalyst might contribute to the lethal oxidative damage to the bacterial cells 30 occurring in the studied soil. These results show that hydroxyl radicals were the major ROS in the Fe-CPP/CaO 2 and Fe(II)/CaO 2 systems and agree with those showing that hydroxyl radicals are the major ROS in Fe(II)/CaO 2 systems 31 .…”

The performance of nCaO2 for BTEX removal: Hydroxyl radical generation pattern and the influences of co‐existing environmental pollutants

“…Though CHCs or surfactants would affect the BTEX oxidation efficiency because that the presence of CHCs or surfactants could compete for with BTEX, the degradation of BTEX could be improved by the following technical methods: (a) increasing the amounts of nCaO 2 and Fe(II) to make the system produce enough , (b) adding Fe(II) in two or three stages rather than one stage to ensure the activity of catalyst, (c) optimizing the catalyst availability by chelating reagents (e.g., Fe(II) was used with EDTA) (Amina, Wu, Si, & Yousaf, ; Bai et al, ; Wang, Peng, Xie, Deng, & Deng, ; Xue et al, ; Xue, Lu, et al, ; Xue, Sui, et al, ). Further improving the efficiency of nCaO 2 /Fe(II) system by the above‐mentioned methods will be investigated in our future work.…”

Insight on the generation of reactive oxygen species in the CaO2/Fe(II) Fenton system and the hydroxyl radical advancing strategy

“…Similarly, Bogan et al [2] found that the removal efficiency was enhanced from 5% to 44% after the substitution of H 2 O 2 with CaO 2 in the treatment of polycyclic aromatic hydrocarbons (PAHs). Moreover, CaO 2 has been used in removing endocrine disrupting compounds, cable insulating oil, toluene, trichloroethylene, benzene, and other organics [3–7]. The treatment process using CaO 2 alone is relatively inefficient, and the introduction of Fe(II) can greatly accelerate the process [6,7].…”