--- --- Run1


-- Run2


 0 100 200 300 400
 Time (minutes)

Figure 4-19. Column exhaustion curve for 30 A pellets (12% TiO2).

Table 4-2. Exhaustion (C/Co = 1) times (minutes) for column studies.
 Pellet Pore Size 140 A 30 A
 Run 1 Exhaustion Times 36 157
 26 48
 50 64
 27
 Run 2 Exhaustion Times 28 132
 35 128
 58 98
 65
 Average Exhaustion Time 40.6 104.5


500


 Both sets of pellets were examined during a column run after exhaustion of the

column and it was observed that the 30 A pellets were still white on the inside, revealing

that the total surface available for adsorption was not utilized. The 140 A pellets were

purple throughout their interior, revealing that the available space for adsorption had been

exhausted. Thus, the small pore size of the 30 A gels inhibits the transit of CV solution

through the porous matrix. Therefore, the 140 A sized gels exhibit the greatest efficiency

in utilizing its surface area for adsorption and its photocatalytic ability to regenerate.