2.4. Effect of solution pH
The effect of initial solution pH was determined by agitating 50 mg of (ABP) sorbent and 50mL of dye
solution of initial basic dye concentration of 20 mg/L at different solution pH ranging from 2 to 10.
Agitation was provided for 1 h contact time which is sufficient to reach equilibrium with a constant
agitation speed of 600 rpm and 18±2°C. The pH was adjusted by adding a few drops of diluted NaOH or
HNO3.