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Combined catalytic oxidation and activated carbon adsorption of dioxins



A mechanical mixture of lignite-based activated carbon (AC) and V2O5-TiO2-catalyst (CAT) is applied to destroy gas-phase polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) at high concentration (9.8 ng I-TEQ Nm−3). Even at low temperature (160°C), the mix of AC/CAT shows high removal efficiency (RE) and destruction efficiency (DE). Varying the proportions of catalyst to AC has slight effect only on the DE-value, but the RE-value augments with rising ratio of AC, benefiting from enhanced adsorption on AC. When temperature is 160°C and the proportion of AC and CAT is 3:2, with oxygen concentration rising from 0 to 20%, the DE-value even amplifies from 27 to 82%, by conversion of V4+OX into higher oxides. In the presence of ozone, PCDD/Fs are further broken down and the DE-values of high-chlorinated congeners surge. In the presence of ozone, AC breaks down to black brown flock, which contains more than 50 wt % carbons. Both reducing the content of AC and increasing the reaction temperature restrain the production of flock. The best condition occurred at 200°C in the presence of ozone with the DE of 98%, when the proportion of AC and CAT is 1:1. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 346–350, 2015