Chloride ion (Cl) is one of the most common anions in the aqueous environment. A mathematical model was developed to determine and quantify the impact of Cl on the oxidization rate of organic compounds at the beginning stage of the UV/persulfate (PS) and UV/HO processes. We examined two cases for the UV/PS process: (1) when the target organic compounds react only with sulfate radicals, the ratio of the destruction rate of the target organic compound when Cl is present to the rate when Cl is not present (designated as r/ r) is no larger than 1.942%; and (2) when the target organic compounds can react with sulfate radicals, hydroxyl radicals and chlorine radicals, r/ r, can be no larger than 60%. Hence, Cl significantly reduces the organic destruction rate in the UV/PS process. In the UV/HO process, we found that Cl has a negligible effect on the organic-contaminant oxidation rate. Our simulation results agree with the experimental results very well. Accordingly, our mathematical model is a reliable method for determining whether Cl will adversely impact organic compounds destruction by the UV/PS and UV/HO processes.

Increasing numbers of cement furnaces have applied selective catalytic reduction (SCR) units for advanced treatment of NO in the flue gas. However, the SCR catalysts may face various poisons, such as acidic, alkaline, and heavy metal species, in the fly ash. In this work, we studied the deactivation mechanisms of multipoisons (Ca, Pb, and S) on the CeO2–WO3/TiO2 catalyst, using the in situ diffuse reflectance infrared Fourier transform spectroscopy method. Calcium promoted the conversion of Ce­(III) to Ce­(IV) and, thus, (i) suppressed the redox cycle, (ii) decreased the NO adsorption (monodentate NO3 – and bridged NO2 –), and (iii) enriched the Lewis acid sites. Pb­(IV) blocked Ce2(WO4)3, aggravating the electronegativity of W6+, which inhibited (i) the binding stability of tungsten and ammonia species, (ii) bridged NO3 – (bonded to tungsten), and (iii) the Brønsted acid sites. The multipoisoning processes enriched O2– by repairing partial surface oxygen defects, which suppressed O2 2– and O–. Sulfur occupied the surface base sites and formed PbSO4 after Ce2(WO4)3 was saturated.

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