Synthesis of Glue-Free NaA Zeolite Granules from Natural Kaolin for the Adsorption of Pb(II) Ions in Aqueous Solution Using a Fixed-Bed Column Study

NaA zeolite-coated metakaolin granules (MKG@NaA) were successfully synthesized from kaolin mineral by primary growth in the hydrothermal reaction without using glue or a seed crystal. The XRD and SEM analysis results revealed that a layer of NaA zeolite with a typical cubic shape and high crystallinity formed on the surface of kaolin granules. The obtained material was used as an adsorbent for lead metal ion Pb­(II) adsorption studies in a fixed-bed column configuration. The operation factors such as the solution inflow rate, Pb­(II) concentration, and column height were investigated. The results showed that the adsorption capacity of the material increased with increasing column height and initial concentration of the influent and decreased with increasing flow rate. With the test parameters at the Pb­(II) concentration of 100 mg·L–1, the adsorbent bed height of 8.1 cm, and the inflow rate of 2.5 mL·min–1, the lead ion adsorption capacity was 118.5 mg·g–1. The Thomas, Yoon–Nelson, and bed depth service time models were applied to describe the breakthrough curves for Pb­(II) ion removal by a fix-bed column using the MKG@NaA absorbent and to predict the column performance under different experimental conditions with good linearity (R 2 > 0.95).