Minerals and Rocks

Natural Egyptian kaolinite was used as a stating material in the synthesis of Na-A zeolites under different conditions. The synthetic Na-A zeolites were characterized by XRD and SEM; surface area was measured using N2 adsorption and the BET equation. The effects of different parameters such as contact time, initial iron concentration and adsorbent mass in the uptake of iron by the synthetic zeolites were studied. For Na-A zeolite prepared after fusion of kaolinite (ZAF), the maximum removed amount of iron (5.62 mg/g) occurred after 5 min of contact time and decreased to 4.66 at equilibrium, while Na-A zeolite prepared after calcination of kaolinite (ZAC) removed an amount of 3.9 mg/g after 5 min and reaching the maximum value (4.3 mg/g) after 8 h. By increasing the adsorbent mass from 0.4 g to 0.6 g, the removal efficiency of iron increased from 45 % to 87.6 % for ZAF and from 35 % to 86.7 % for ZAC by keeping the other experimental conditions constant. The Langmuir model gave a better fit than the Freundlich model for the synthetic zeolites. Adsorption kinetic data correlated well with pseudo-second-order model, which suggested that the uptake process might be chemical sorption in the synthetic zeolites. Response surface modeling (RSM) including a central composite rotatable statistical design (CCRD) of second order quadratic polynomial model was used to detect the optimum conditions for the maximum removal of iron. Based on the polynomial model, the removal efficiency of iron could be enhanced Based on the polynomial model, the removal efficiency of iron could be enhanced in ZAF and ZAC through a series of suggested solutions.