Biosensor for the evaluation of biochemical oxygen demand using photocatalytic pretreatment

A highly sensitive biochemical oxygen demand (BOD) sensor using photocatalytic pretreatment was developed to evaluate low BOD levels in river waters. The photocatalytic oxidation was carried out in a commercial TiO2 as a semiconductor and a 6 W black-light tube as light sources. The photocatalytic oxidation was investigated about the effects of irradiation times, TiO2 concentrations, and pH on the sensor response. The optimal irradiation time was 4 min. TiO2 concentrations gave the optimum response to the BOD sensor at 1% (w/v). The sensor response was increased with increasing pH. The sensor responses obtained by photocatalysis to river samples were higher than those obtained without photocatalysis. A fairly good correlation between the values obtained by the photocatalytic pretreatment method and BOD5 was acquired.