Relationship between theoretical oxygen demand and photocatalytic chemicaloxygen demand for specific classes of organic chemicals

The oxidation behavior of twenty organic chemicals from four different clas ses (sugars, benzene derivatives, alcohols and carboxyl acids) were investi gated using the official chemical oxygen demand (COD) methods (i.e., perman ganate and dichromate methods) and their oxidation levels compared with the theoretical oxygen demand (ThOD) values. In addition, the correlation betw een the official COD and ThOD values was also examined using the CODMn, Cr method and their relative merits were considered. With the same set of samp les, this study also examined the relationship between ThOD values and the response values of a photocatalytic COD sensor which has been developed to overcome several of the problems associated with the official COD methods. The relationship of the response values determined by the photocatalytic CO D sensor to those ThOD values was obtained: r = 0.96 for the 20 organic che micals from each different chemical class.