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

In this study, nano-CaO2 (nCaO(2)) was successfully synthesized and constituted the nCaO(2)/Fe(II) system applying to remediate BTEX, which are typical mixed pollutants in contaminated groundwater. The particle size of the synthesized nCaO(2) was 108.91 nm, and it displayed better BTEX remediation performance than that of commercial CaO2. The innovative generation pattern of hydroxyl radicals (HO) in the nCaO(2)/Fe(II) system has been investigated using benzoic acid as the HO probe, and the proper molar ratio of nCaO(2)/Fe(II) was optimized as 1/1. Over 90% of BTEX was removed in 180 min with the nCaO(2)/Fe(II)/BTEX molar ratio of 40/40/1. Further experiments evaluated the influence of co-existence of mixed pollutants chlorinated hydrocarbon compounds (CHCs) or surfactant constituents on BTEX remediation performance. The experimental results suggested that CHCs have limited influence on BTEX removal rate and surfactants have negative effects on BTEX remediation performance in the experimental conditions. In conclusion, the findings in this study could give some inspirations to apply the nCaO(2)/Fe(II) process in remediating co-existing pollutants in contaminated groundwater. Practitioner points nCaO(2)/Fe(II) system applied to remediate mixed contaminants. HO generation pattern of the nCaO(2)/Fe(II) system has been investigated. The influence of chloride hydrocarbon compounds have been studied. The effects of surfactants were evaluated.