carbon (particle diameter 300e500 mm) was added to 250 cm3
bottles containing 100.0 cm3 of reactive dye of varying concentration:
1.0 105e1.2 103 mol/dm3. The bottles were
sealed and placed in a thermostated shaker (GFL 1083, Germany)
for one week until equilibrium was achieved. The adsorption
behavior of the reactive dyes on the activated carbon
was studied at four temperatures (298, 308, 318, and 328 K).
The adsorption equilibrium isotherm experiments were
repeated in duplicate and the average values are reported.
2.4. Effect of solution pH and ionic strength on
reactive dye adsorption
The effect of solution pH and ionic strength on dye adsorption
was investigated according to the following procedure. A
mass of 0.250 g of dried activated carbon (300e500 mm particle
diameter) was added to a number of 250 cm3 glass bottles
containing 100.0 cm3 of 6.0 104 mol/dm3 dye solution.
The pH of the dye solutions was adjusted over the range pH
2epH 10 using 0.5 M HNO3 or 0.5 M NaOH solutions (prior
to the addition of the adsorbent). The bottles were sealed and
placed in the shaker at 25 1 C for seven days. The effect of
ionic strength on the adsorption of the dyes was investigated
according to the following procedure. A mass of 0.250 g of activated
carbon (300e500 mm particle diameter) was added to
1000 cm3 solutions of 6.0 104 mol/dm3 of dye with varying