mW/cm2. Based upon this undesirable change, crystal violet was excluded for future

destruction studies.

 Subsequently, the remaining dyes were evaluated for photolysis at various

concentrations (0.5 mg/L to 10 mg/L). At 0.5 mg/L, there was a 98% and 20% change

between the initial absorbance readings for MB and MG respectively, compared to their

final readings after two hours of UV exposure (0.45 mW/cm2) (Figure 4-2). Large

discrepancies were also observed at 1 mg/L and 2 mg/L. Therefore, MB and MG were

eliminated as viable candidates to investigate the photocatalytic ability of the composites.

For RR (see Figure 4-3), the largest change in absorbance was only 13% at a flux of 1.1

mW/cm2, the highest flux achievable. Thus, RR was chosen for the photocatalysis

studies. The amount of photolysis was not subtracted from the results of the destruction

studies.



 25

 c 0.45 mW/cm^2
 S20 -- 0.75 mW/cm^2
 0
 o1
 ] 1.1 mW/cm^2



 I 10
 )



 5



 RR CV MB MG
 Dye

Figure 4-1. Photolysis of dyes as a function of UV flux for 2 hours of exposure.