A stock solution of 1000 mg/L of Cr was obtained by dissolving potassium dichromate (Merck Company) in distilled water.
The test solutions of various concentration ranges from 10 to 100 mg/L were prepared from the stock solution. The solution
pH was adjusted using 0.1 M HNO3 and 0.1 M NaOH at the beginning of the experiment and not controlled afterward.
The conical flasks (250 mL) were shaken at 120 rpm in a temperature controlled rotatory shaker.