Ion exchange in natural zeolite packed column

Abstract

Turkish natural clinoptilolites were examined to evaluate their ion exchange performance for the removal of copper, nickel and cobalt ions by performing both batch and packed column experiments.Initial metal solutions were prepared using metal nitrate solutions at various concentrations.All of the experiments were carried out at 29oC.Before performing the ion exchange experiments zeolites were characterized and their clinoptilolite contents were determined quantitatively as 80 and 64 % for zeolites named as CP1 and CP2, respectively.The copper exchange capacities of CP1 and CP2 were determined from equilibrium studies as 10.01 mg (0.32 meq) Cu2+ / g CP1 and 8.33 mg (0.262 meq) Cu2+ / g CP2. Ion exchange capacity of CP2 zeolite was determined as 6.64 mg (0.226 meq) Ni2+ / g and 4.55 mg (0.154 meq) Co2+ / g.The equilibrium behaviour of the system was best described by Langmuir model.Experiments were designed to investigate the optimum parameters and significance of the interactions between these parameters.In column studies, the parameters such as packing height, inlet metal concentration and flow rate were investigated.The concentration of the metals in the sample solutions which were taken from the exit of the ion exchange column at specific time intervals were analyzed by using Optical Emission Spectrometry (ICP-OES).Afterwards, by making use of the data obtained from ICP-OES, breakthrough curves were constructed.By the help of these curves, breakthrough capacity and ion exchange capacity of natural zeolites were calculated.The ion exchange capacity of CP2 zeolite was calculated as 8.04 mg Cu2+/g CP2, which was consistent with the capacity calculated from batch experiments, 8.33 mg Cu2+/g CP2.Also, breakthrough points were determined. Furthermore, solid phase was also analysed for determining its crystal structure and chemical composition using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) devices (Philips XL 30S FEG).In addition to these, natural zeolite particles which have been ion exchanged throughout this process were regenerated using 0.2M and 1.7M of NaCl solutions.According to regeneration studies, it was determined that 94 and 95% of copper were recovered within the first 100 minutes for both experiments.After the experiments were performed, model equations were applied to the system in order to be able to investigate the dynamic behavior of the system.As a result of this simulation, breakthrough was well predicted.