Fixed Bed Column Adsorption Studies Using Fly Ash for Removal of Cadmium from Aqueous Solution

In the present paper, adsorptive removal of cadmium from synthetic wastewater using a 2 cm diameter fly ash column was studied through three column adsorption experiments by varying column depths (10, 15 and 20 cm). Study results showed fly ash to be an effective adsorbent for cadmium removal. Column design parameters such as depth of adsorption zone (6 cm), critical bed depth (1.3 cm), adsorption capacity (480.82 mg/l) and adsorption rate constant (0.0111 l/mg min) are calculated using bed depth service time approach. Using the same method effect of varying flow rate (5, 8 and 10 ml/min) and initial cadmium concentration (15 and 20 mg/l) was studied and the corresponding model predicted service times conformed well with the experimentally obtained results from three more column studies. Negligible leaching of adsorbed cadmium from exposed fly ash column was observed during two desorption studies. © 2014, The Institution of Engineers (India).