| Abstract
| - Photodegradation of spent Bayer liquor has been carried out in an 18-L pilot-scale continuousannular photoreactor. The performance of the reactor was studied with respect to various processparameters such as the gas flow rate, liquid flow rate, initial solution pH, initial substrateconcentration, light intensity, and catalyst loading. The average reaction rate and overallconversion of Bayer liquor, in terms of total organic carbon, have been found to be stronglydependent on all of these parameters. Despite the very dark color and high initial pH (ca. 12)of the reaction mixture, significant conversion (25−35%) was achieved within about 2 h ofoperation, showing a considerable improvement over the existing industrial oxalate removalmethods. Notwithstanding the complex composition of the spent Bayer liquor, the rate datacould adequately be analyzed in terms of simple linear or hyperbolic-type kinetic expressions.
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