All used chemicals were of analytical grade and were used
without further purification. Phosphoric acid (85%), methanol,
toluene, acetic acid, diphenyl amine and sodium hydroxide were all
purchased from Frutarom. Potassium hydrogen phthalate (KHP)
and zinc chloride were purchased from Alfa Aeser, and sodium
nitrite from Avokado. Commercial granular activated carbon (CAC),
Aktivkohle (Hydraffin CC8X30), from Donau Carbon, with surface
area (1000 m2
/g), and particle size (0.5e2.5 mm)