Removal of Chromium (III) and Arsenic (III) by using Coal Ash as Adsorbent

The adsorption of Cr(III) and As(III) by using coal ash from thermal power plants in batch mode ,The effect of adsorbent agitation speed, dose, pH, contact time and agitation speed on the adsorption of Cr(III) and As(III) by coal ash is examined. Adsorption equilibrium was achieved in 50–55 min. The Langmuir, Temkin and Freundlich adsorption isotherms were used to observed sorption phenomena. The maximum Cr (III) removal was 2.62 mg of Cr per gram of coal ash and As (III) removal was 2.45 mg of As per gram of coal ash as evaluated from Langmuir isotherm. The heat of sorption was in the range 3.75–3.87 kJ/mol as calculated from Temkin isotherm. Best results were obtained at pH > 5. It is proposed that low rank coals ash can be used for removal of toxic metals like Chromium and Arsenic from industrial waste water effluents.