PHOTOCATALYTIC DEGRADATION OF PCBS IN TIO2 AQUEOUS SUSPENSIONS

A generator-column technique was used to prepare aqueous solutions of PCBs. The degradation of 2-chlorobiphenyl, Aroclor 1248, Aroclor mixtu re (1221, 1016, 1254, and 1260) and St. Lawrence River water by simula ted sunlight or sunlight has been investigated in the presence of aque ous suspensions of TiO2. The effect of TiO2 concentration and pH on th e degradation rate of PCBs have been studied. The reaction rate follow ed apparent first-order kinetics and increased with increasing TiO2 co ncentration. The half-life of the degradation process for 2-chlorobiph enyl is 20 minutes at pH 10 and 9 minutes at pH 3 in the presence of 2 5 mg/L of TiO2. Less chlorinated PCBs decomposed faster than higher ch lorinated ones. The rate constants and half-lives of individual PCBs i n the commercial PCB mixture and St.Lawrence River water were also mea sured. (C) 1996 Elsevier Science Ltd