The performance of chlorobenzene degradation in groundwater: comparison of hydrogen peroxide, nanoscale calcium peroxide and sodium percarbonate activated with ferrous iron

Abstract

The chlorobenzene (CB) degradation performances by various oxidants, including hydrogen peroxide (H2O2), nanoscale calcium peroxide (nCaO2) and sodium percarbonate (SPC), activated with ferrous iron (Fe(II)) were investigated and thoroughly compared. The results showed that all tested systems had strong abilities to degrade CB. The CB removal rate increased with increasing dosages of oxidants or Fe(II) because the generation of reactive oxygen species could be promoted with the chemical dosages' increase. Response surface and contour plots showed that CB could achieve a better removal performance at the same H2O2 and Fe(II) molar content, but the Fe(II) dosage was higher than that of oxidants in the nCaO2 and SPC systems. The optimal molar ratios of H2O2/Fe(II)/CB, nCaO2/Fe(II)/CB and SPC /Fe(II)/CB were 5.2/7.6/1, 8/8/1, and 4.5/8/1, respectively, in which 98.1%, 98%, and 96.4% CB removals could be obtained in 30 min reaction. The optimal pH condition was around 3, while CB removal rates were less than 20% in all three systems when the initial pH was adjusted to 9. The oxidative hydroxyl radicals (HO•) and singlet oxygen (1O2) had been detected by the electron paramagnetic resonance test. Based upon the results of liquid chromatograph-mass spectrometer analysis, the pathways of CB degradation were proposed, in which 1O2 roles were elaborated innovatively in the CB degradation mechanism. The CB degradation performance was significantly affected in actual groundwater, while increasing the molar ratio of oxidant/Fe(II)/CB was an effective way to overcome the adverse effects caused by the complex of actual groundwater matrix.

Current Challenges and Advancements on the Management of Water Retreatment in Different Production Operations of Shale Reservoirs

“…Therefore, the use of treated water to continue the operations should be strictly promoted by the World Health Organization to [31][32][33][34][35][36][37][38][39][40]. These hazardous materials consisted of solid and heavy metals, chemical agents in produced water that might be highly toxic to the environment [41][42][43][44][45][46][47][48][49][50][51].…”

A Pandoraea sp. strain efficiently degrades chlorobenzene via monooxygenation pathways with high potential for groundwater bioremediation

“…Chlorobenzene (CB), as a signi cant chemical production intermediate and solvent, is widely used in the pesticide, plastic, pharmaceutical and dye industries (Sun et al 2021). While chlorobenzene is a toxic and harmful volatile organic compound (VOC) that has been listed as a priority control pollutant by the U.S. EPA.…”

Hydrogen peroxide electrosynthesis using commercial carbon blacks as catalysts: the influence of surface properties and adsorption performance

“…As a recognized green chemical oxidant, H 2 O 2 is widely used in the fields of industrial bleaching, 1 chemical synthesis, 2 medical disinfection 3 and environmental purification 4 . The global demand for H 2 O 2 is progressively increasing and is expected to increase to 6 million tons in 2024 5 .…”