<b>MER</b> Zeolite with Remarkable Pb<sup>2+</sup> and Cd<sup>2+</sup> Removal Capability Cost-Effectively Synthesized from Postprocessed Natural Stellerite
Yufei Wang, Shuang Liu, Junyao Pan, Haoyang Zhang, Binyu Wang, Wenfu Yan
Abstract
MER zeolite, a low-silica zeolite with an 8-membered ring aluminosilicate framework, has been recognized as a promising material in sorption, separation, and ion-exchange applications. Herein, we developed a cost-effective and rapid method to convert parent zeolite H- STI, which was derived from natural stellerite, into MER zeolite through interzeolite conversion with a crystallization time of 8 h. This MER zeolite exhibits high efficiency in removing Pb 2+ and Cd 2+ from simulated heavy metal wastewater over a pH range of 3–8. It also shows excellent selectivity in the presence of competitive cations, including Na +, K +, Ca 2+, Mg 2+, Zn 2+, Cu 2+, and Co 2+ . At 25 °C, with a MER -S dosage of 1/3000 g·mL –1 for Pb 2+ and 1/500 g·mL –1 for Cd 2+, the removal efficiencies were 99.7 and 99.9%, respectively. The distribution coefficients were 1097 L·g –1 for Pb 2+ and 550 L·g –1 for Cd 2+, and the sorption capacities reached 513 mg·g –1 for Pb 2+ and 171 mg·g –1 for Cd 2+, indicating that the product MER zeolite is one of the highest sorbents for Pb 2+ and Cd 2+ reported for zeolitic materials. The sorption for Pb 2+ and Cd 2+ both follows the chemisorption-dominated mechanism, driven by the ion-exchange process between the K + in the channels MER -S and the Pb 2+ or Cd 2+ in solution. This work highlights the potential of rapidly synthesized MER zeolite for the effective removal of heavy metal cations, emphasizing its performance and practical applicability.