Deeolourization and COD removal fm synthetic wastewater containing Reactive Btilliant Orige K-R (RBOKR) dye using sonophotoeatalydc technology was investigated. Experimental results showed that this hybrid technology could eflleiently remove the eolour and aduce COD from the synthetic dye-cont aining wastewater, and that both processes fonowed pseudo first-order kinetics. At the condition of 0.1 m3 h-I airflow, 0.7S gdm-3 titanium dioxide and 0.5 mmol dm 3 RBOKR solution, the rate constants of decolourlzation and COD removal we 0.0750 d 0.0143 min-1 respectively for the sonophotoeatalytic process; 0.0197 d 0.0046 min respectively for the phot at Mytic process and 0.000S and 0.0001 min J respectively for the sonochieal process. The rate constants of sonophotocatalysis were greater than that of both the photocatalytic and sonochemical processes either in isohtion or as a sum of the individual prcess, indicating an appannt synergetic effect heeen the photo-and sono-processes.

Ag-TiO2 composite film supported on indium-tin oxide (ITO) glass was used as photoanodes to investigate the feasibility of a hybrid technology of Ag deposition combined with the application of an external electric field. The results showed that the deposited Ag and applied anodic bias have an apparent additive effect for suppressing the recombination between the photogenerated charge carriers and enhancing the photocatalytic oxidation of formic acid.

Degradation of formic acid was investigated using a novel photoelectrocatalytic reactor with a porous titanium plate as an air distributor as well as an electrode. By the comparison of the COD removal efficiencies from the solution containing formic acid for three processes, direct electro-oxidation, photocatalysis and photoelectrocatalysis, a significant photoelectrochemical synergetic effect was observed in the photoelectrocatalysis process. The synergetic effect was assessed with a new parameter, synergetic factor (SF). The effects of various operating conditions, such as applied cell voltage, treating time, airflow, initial pH value, catalyst amounts and conductivity of solution, on the SF were investigated as well. It was found that the SF was considerably dependent on these operating conditions, moreover, not simply proportional to them.

The photoelectrochemical degradation of methylene blue in aqueous solution was investigated with three-dimensional electrode-photocatalytic reactor. It was found that the methylene blue could be degraded more efficiently by photoelectrochemical process than by photocatalytic oxidation or electrochemical oxidation alone. The decolorization efficiency and COD reduction were 95% and 87% for a photoelectrochemical process, respectively, while they were only 78% and 68% for a single electrochemical process and 89% and 71% for a single photochemical process. The TOC reduction of the former also reached as high as about 81% within a reaction time of 30.0 min. And these degradation reactions conformed to pseudo-first-order kinetics.