After the optimum pH value was found, the effect of adsorbent
dosage was investigated. For the adsorbent dosage studies, 50 mL
of 2 104 mol dm3 RB19 was added to each Erlenmeyer flask
with different adsorbent amounts (0.01–0.04 g) at a constant pH.
After the equilibrium was reached, the concentration of the dye in
the solution was determined by using a UV–vis spectrophotometer.