3. Materials and methods
3.1. Materials
Synthetic colored wastewater containing an organic model pollutant
(Reactive Yellow 84), commonly used as a textile dye,
was obtained from Boyakhsaz Company, Iran. Other chemicals
potassium peroxydisulfate (K2S2O8), sulfuric acid and sodium
hydroxide were of laboratory reagent grade (Merck Co.,
Germany) and used without further purification.
3.2. Experimental procedure
The total solution volume for all applied experiments was 500 ml,
and process duration was 120 min. The temperature was controlled
through a thermostat. The required amounts of RY84
from stock solution into the reactor and then diluted with deionized
water to 250 mL.ThepHof each solutionwas adjusted to the
desired value by adding 0.1 mol/L NaOH or 0.1 mol/L H2SO4.
The reaction was started by adding different amounts of potassium
peroxydisulfate solution to the reactor after the pH was adjusted.
The start timewas recorded tomeasure the reaction period
when the potassiumperoxydisulfate solutionwas added. Samples
were periodically taken out of the reactor using a pipette and then
absorbancemeasurements of the reaction solutions were immediately
performed to avoid the experimental errors.
3.3. Analysis
Concentration of RY84 in solution at different times was obtained
by measuring the absorbance at maximum absorption
wavelength (226 nm) and the calculation of decolorization decay
was obtained from the calibration curve prepared earlier.
An UNICO (USA) UV spectrophotometer (model-2001SUV)
was employed for absorbance measurements by using a quartz
cell of path length 1 cm. The calibration curve equation of
RY84 dye was obtained to be YRY84 =13.8XRY84; R2 =
0.996; where YRY84 is the solution absorbance at 226 nm and
XRY84 the RY84 concentration in mgL1 and the range of concentration
was 0–50 mgL1.