6.1.1. “Batch” process
In the batch process a certain amount of natural or modified zeolites is used, which are placed in contact with a solution of synthetic or real samples of water at certain times. Bach procedure is usually carried out at constant temperature and hydrodynamic conditions. The amount of immobilized ions on the zeolite is presented as equilibrium distribution of ions between the natural or modified zeolites and the solution.
The removal efficiency of metal ions by natural zeolite depends on the quantity and exchange capacity as well as the presence of other cations and anions in the treated water. With increasing concentration of metal ions in water the removal efficiency increases of theseionsusing naturalzeolite(from 500 mg/L to 1 g/L). Natural and modified zeolites are efficient at low concentrations of different metal ions like Zn2+ (concentration from 1 to 5 mg/L) and Fe3+ (concentrations from 0.2 to 2.0 mg/L) about 50-60%. In many studies revealed the values of the maximum capacity adsorption, Qmax for metal ions removal from synthetic and real water. On Figure 9 Qmax values on cations uptake from water by natural zeolites from different deposits are summarized [76].