OCR Text |
Show necessary to directly measure the rate of excitation and efficiency of reaction for a variety of representative molecules before full-scale treatment system can be designed. For this reason, we are conducting a development program which includes a series of carefully designed laboratory studies. Experimental Design The photothermal detoxification process outlined above and illustrated in Figure 1 m a y be described mathematically as; [17] fr = exp[-(kgnd + <|>rkab)y (1) where fr is the fraction remaining, kgnd is the rate of ground state (purely thermal) oxidation (s_1), <|>r is the photochemical quantum yield, kab is the rate coefficient of ultra violet ( U V ) photon absorption (s*1), and t, is the mean residence time in the reactor (s). Equation 1 represents the global batch reactor perfonnance model for the photothermal detoxification process. In order to use Equation 1 to predict the performance of a prototype P D U , and hence aid in the interactive design of the prototype unit, typical values of k„nd, §T, and kab must be known. Therefore, the experimental portion of the current project will concentrate on obtaining these values. It has been shown that the rate of thermal oxidation may be described by relatively simple pseudo-first-order kinetic models.[19] Specifically, fr = exp(-kgndg (2) so, kgnd = lnd/y/t, (3) Therefore, kgnd may be found by measuring the fraction remaining following a purely thermal exposure of known duration. Furthermore, the temperature dependence of kgnd may be found from; kgnd = Aexp(-EyRT) (4) or, ln(kgnd) = ln(A) - E^RT (5) where A is the frequency factor (s'1), Ea is the molar activation energy (cal mol*1), R is the 6 III-19 |