Equilibrium, kinetic, and thermodynamic studies of the Ca2+ and Mg2+ ions removal from water by Duolite C206A

The uptake of Ca2+ and Mg2+ ions from synthetic aqueous solutions by Duolite C206A was studied in static-batch mode. Results revealed that there is no need of pH adjustment. The equilibrium is reached after 30min with 0.5g of resin at 25 degrees C. Equilibrium data were well fitted by Langmuir isotherm model. Maximum uptake capacities Q(max) were about 23.04mg Mg2+/g and 64.10mg Ca2+/g. The pseudo-second-order model was found as the best to explain the ions exchange kinetics effectively. The uptake of Ca2+ and Mg2+ ions by Duolite C206A is exothermic and the process is spontaneous.