A combination of ultrasound and oxidative enzyme: sono-biodegradation of substituted phenols

Sonolysis, enzyme treatment, and a combination of the two processes were tested for the degradation of substituted phenols (phenol, p-chlorophenol, p-bromophenol, p-iodophenol, p-methoxyphenol, p-cresol and p-nitrophenol) in aqueous medium. These organic pollutants are divided into three groups according to their degradation behaviour. In group (I), p-nitrophenol, horseradish peroxidase (HRP) in presence of hydrogen peroxide had a negligible effect on its decomposition. The combined method showed the same effect as sonolysis. Therefore, it is convenient to degrade p-nitrophenol by ultrasonic waves alone. In group (II), p-methoxyphenol and p-cresol, the combined method was approximately the same as enzyme treatment. It means that, the ultrasound had a negligible effect and the enzyme treatment alone was more favourable. Phenol and its halogenated compounds (choloro, bromo and iodo) were placed in group (III) and showed different behaviour than the two mentioned cases. The combined method was more efficient than the sonolysis and enzyme treatment individually. It should be noted that the effect of enzyme on this group (III) was in the medium level in compare of the two other groups (I and II) which the enzyme had a lower and higher effects respectively.