Then pH adjustments were made with sodium hydroxide or nitric acid. The flask opening

was then covered with parafilm to maintain a closed system with a limited amount of

dissolved oxygen (DO). In a system designed for NASA, oxygen would be a limiting

factor due to the problem of continually supplying oxygen for water treatment for long

duration space flight. The flasks were placed within a box containing four magnetic

mixers relatively equidistant from a single 4-Watt UV lamp. The UV exposure time was

two hours and the percent destruction was calculated by comparing the initial and final

absorbance readings using a Hach DR/4000U (Loveland, Colorado) Spectrophotometer at

RR's peak absorption wavelength of 538 nm. The spectrophotometer gave a linear

response across the concentration range for each dye. The UV intensity (mW/ cm2) was

varied by changing the position of the mixers in regard to the lamp and by the use of

additional lamps. UV intensity (wavelengths between 320 to 380 nm) was measured with

a VWR Ultraviolet Light Meter (Atlanta, GA). Each mixer was placed where the desired

UV intensity was achieved at the mixer's center.

 The adsorption studies were performed as follows: 30 mg of gel was added to 100

mL of 10 mg/L CV solution with no bicarbonate added. The studies were conducted at a

pH of 4, using nitric acid and sodium hydroxide for the pH adjustments. The flasks were

covered with parafilm and placed in a box with no penetration of light and allowed to mix

for 24 hours. The percent adsorbed was calculated from the absorbance reading at a

wavelength of 590 nm.

 The BET (Brunauer, Emmett, and Teller equation) surface area and pore volume

analysis was performed on a Quantachrome NOVA 1200 Gas Sorption Analyzer

(Boynton Beach, FL). The powdered samples were outgassed at 110 C for