RESUMO
Four lead dioxide electrodes on Ti substrates were prepared by thermal-deposition and electro-deposition. Scanning electron microscopy (SEM) was used to study the characterization of surface of electrodes. High performance liquid chromatograph was applied to detect the concentration of the aromatic hydroxylation 2,5-DHBA to determine the amount of .OH with 2-HBA as the capture matter. This study investigated effect of different coated electrodes and inhibitors on degradation of phenol by hydroxyl radicals generated by electrolysis in terms of the measurement of hydroxyl radicals and degradation of phenol. The experimental results show that the highest concentration of hydroxyl radicals generated by thermal-deposition, electro-deposition mingled with nothing, electro-deposition mingled with Bi or La were 0.781 micromol/L, 1.048 micromol/L, 1.838 micromol/L, 2.044 micromol/L, respectively. When phenol was electrolyzed by electrodes prepared by the four electrodes, the removal efficiencies of phenol at 1.5 h were 87.30%, 93.55%, 97.95% and 98.70%, and TOC removal efficiencies at 5 h were 86.76%, 94.26%, 98.53% and 99.60%, respectively. The highest concentration of hydroxyl radicals when CO3(2), PO4(3) or CH3COO-existed was no detected, 0.170 micromol/L, 0.270 micromol/L, and the removal efficiencies of phenol were 99.06%, 99.98% and 99.79%, respectively. The degradation of phenol with electrodes prepared by electro-deposition is better than the electrodes prepared by thermal-deposition, and the electrode mingled with La is better than the electrode mingled nothing and with Bi. The electrode mingled with La is the best. The degradation of phenol is inhibited when CO3(2-), PO4(3-) or CH3COO- exists, and the inhibiting effect of CO3(2-) is the strongest. The catalytic characteristics of electrodes and degradation of phenol by them are different when the electrodes are prepared by different methods or with different additives; the higher the concentration of hydroxyl is, the better the degradation of phenol is. Inhibitors capture hydroxyl radicals, and isn't in favor of degradation of phenol.
