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Degradation efficiency of 4-bromo-2-chlorophenol (BCP) containing both chlorine and bromine substituents in Co/PMS process was investigated in the light of a wide range of substrate, oxidant, catalyst concentrations and pH value. The effects of chloride ion (Cl−) on degradation kinetics, total organic carbon (TOC) removal and intermediates formation during BCP depletion in Co/PMS system were studied. The kinetics results demonstrated that the dual effect of Cl− on BCP depletion in Co/PMS system due to different mechanisms involved. High concentrations of Cl− (>5 mM) can significantly promote the degradation of BCP, but did inhibit BCP mineralisation to a certain extent which was closely related to Cl− content. High degradation rates but lower mineralisation rates were found in the laboratory experiments, owing to the fact that BCP was mainly transformed to new halogenated intermediates instead of complete mineralisation. Gas chromatograph-mass spectrometer (GC-MS) data verified that a series of chlorinated by-products were formed during BCP decomposition process involving of the participation of Cl−. The proposed degradation pathways of BCP and its derivatives in presence of Cl− were discussed on the basis of intermediate products including the undesirable halogenated by-products recognised by GC-MS. These results might offer some new perspectives on the transformation fates of BCP by utilising Co/PMS regent. [ABSTRACT FROM AUTHOR]

The oxidation of sulfur dioxide (SO2) to sulfate in the atmosphere is an important concern in regional air quality, global climate change, and human health. While gas-phase and liquid-phase oxidation of SO2 are widely regarded as important sources of sulfate, the contribution of the heterogeneous oxidation process on particle surfaces is controversial. Recently, this heterogeneous chemistry has been considered to be an important mechanism that is missing in current models to explain sulfate concentrations observed in haze episodes in East Asia. Therefore, the heterogeneous oxidation of SO2 on particles under the conditions of complex air pollution needs to be reassessed. This review summarizes the fundamental understanding of the heterogeneous reactions of SO2 on solid particles such as mineral dust, black carbon, sea salts, organic aerosol, and so on. The factors affecting the mechanism and kinetics of the heterogeneous reactions of SO2, including coexisting components (O3, NO2, H2O2, NH3, and VOCs), reactive sites, surface properties, relative humidity, and illumination, are reviewed. Reactive oxygen species involved in the heterogeneous oxidation of SO2 on particles are discussed. To our knowledge, while previous reviews have appeared on the oxidation of SO2 in the aqueous-phase, this is the first review on the atmospheric heterogeneous reactions of SO2 on the surface of solid particles, which can be of help in understanding the sulfur cycle in the atmosphere and its environmental impacts. A number of recommendations for future research are also presented. [ABSTRACT FROM AUTHOR]

The removal of phenol compounds (such as phenol (Ph), 4-chlorophenol (4-CPh), and 4-phenolsulfonic acid (4-APS)) was studied using catalytic ozonation and cerium oxide (CeO2) as the catalyst. Conventional ozonation removes 40% and 30% of total organic carbon (TOC) for 4-CPh and 4-APS, respectively. The presence of the catalyst doubled the TOC removal in comparison with ozone alone. Chloride and sulfate ions, detached from the target compounds, did not affect the mineralization degree. The effect of ions was studied by adding NaCl and Na2SO4 during the ozonation of Ph with CeO2 as a catalyst. The O3-CeO2 process was responsible for 89% TOC removal, while the presence of NaCl and Na2SO4 decreased TOC removal by nearly 50%. Ozonation alone only removed 20% of TOC at 120 min with or without inorganic salts. The presence of salts in the Ph ozonation provoked in detrimental effect in comparison when inorganic ions were produced along with the decomposition of 4-CPh and 4-APS. [ABSTRACT FROM AUTHOR]

The removal of phenol compounds (such as phenol (Ph), 4-chlorophenol (4-CPh), and 4-phenolsulfonic acid (4-APS)) was studied using catalytic ozonation and cerium oxide (CeO2) as the catalyst. Conventional ozonation removes 40% and 30% of total organic carbon (TOC) for 4-CPh and 4-APS, respectively. The presence of the catalyst doubled the TOC removal in comparison with ozone alone. Chloride and sulfate ions, detached from the target compounds, did not affect the mineralization degree. The effect of ions was studied by adding NaCl and Na2SO4 during the ozonation of Ph with CeO2 as a catalyst. The O3-CeO2 process was responsible for 89% TOC removal, while the presence of NaCl and Na2SO4 decreased TOC removal by nearly 50%. Ozonation alone only removed 20% of TOC at 120 min with or without inorganic salts. The presence of salts in the Ph ozonation provoked in detrimental effect in comparison when inorganic ions were produced along with the decomposition of 4-CPh and 4-APS. [ABSTRACT FROM AUTHOR]