Synthesis of fine Na-type zeolite grains from coal fly ash and the assessment of the adsorption capability of lead ions from aqueous solutions

Fine Na-type zeolite grains (ZE) were prepared by dry milling treatment (D-ZE) or wet milling treatment (W-ZE). Then, the prepared samples were characterized. The effective parameters of adsorption capacities including the initial concentration, adsorption temperature, pH, and contact time for lead-ion adsorption were determined. The results revealed that the adsorption capacity of lead ions was in the order of ZE (32.7 mg g−1) < D-ZE (70.7 mg g−1) < W-ZE (166.9 mg g−1). The results of the adsorption processes exhibited increased adsorption temperature, an increased pH of up to 5.0, and increased contact time. Pseudo-second-order model kinetic was observed, and the lead adsorbent isotherm followed the Langmuir and Freundlich models. Finally, one of the adsorption mechanisms was elucidated by analyzing the binding energy of lead (Pb) and lead (Pb) distribution before and after adsorption. Thus, the results serve as useful information for the adsorption of lead ions from aqueous solutions using ZE samples.