REMOVAL OF AQUEOUS HG(II) ON THE BIMETALLIC CATALYST SURFACE SUPPORTED BY ZEOLITE IMIDAZOLATE FRAMEWORK DERIVED CO@NC

Abstract

Mercury (Hg) is a toxic chemical derived from both human activities and natural sources. It has adverse effects on the environment and human health. Recognizing these concerns, the maximum permissible concentration for this chemical in drinking water was denoted as 6 µg/L by the World Health Organization (WHO). Many studies have been dedicated to addressing mercury contamination issues in the past. However, the catalytic removal approach is considered the most suitable method due to its balance of cost-effectiveness and removal efficiency. The effectiveness of materials for the sorptive removal of aqueous contaminants in environmental treatment technologies heavily relies on their ability to be reused. In this study, Zeolitic Imidazolate Framework-67 (ZIF- 67) derived Cobalt N-Doped Carbon (Co@NC) and metal-impregnated (Ru, Pt, and Pd) Co@NC have been synthesized and tested for the effective and sustainable removal of aqueous Hg(II) and its reusability by thermal desorption. Reduced Co@NC can efficiently remove Hg(II), while the metal impregnation enhances Hg(II) reduction to Hg(0) on the catalyst surface. Non-noble metal ZIF- derived Co@NC efficiently treated water contaminated with low Hg(II) concentration. An optimization study revealed that Pd is the most influential metal for Hg(II) reduction, resulting in the fastest catalytic removal kinetics (0.2028 g (mg min)-1). The adsorbed Hg on Pd(4%)-Co@NC and Co@NC surfaces can be recovered via thermal desorption at 500 o C. The catalyst retained its reactivity and stability throughout 5 consecutive cycles, successfully eliminating all Hg species from the water. Co@NC displayed notable promise as a sustainable catalyst for Hg(II) removal in wastewater treatment technologies, emphasizing its enduring effectiveness and capacity for reuse.