Sustainable Application of ZIF-8 for Heavy-Metal Removal in Aqueous Solutions

Water is life, and clean-water demand is increasing daily as a result of rapid population growth and industrial evolution. Nevertheless, due to the inadequate supply and availability of new water sources, there is a need for effective, sustainable removal of contaminants for wastewater reuse. Several treatment approaches that include chemical, physical, and biological methods have been thoroughly tested, with biological treatment being regarded as the most cost-effective and environmentally friendly method. However, the presence of heavy metals and complicated chemicals that are nonbiodegradable limits the use of this cost-effective approach. In this paper, we review the sustainable application of a cheap, water-stable metal-organic framework, the zeolitic imidazolate framework (ZIF-8), with an easier synthesis approach for heavy-metal removal in aqueous solutions. In this review, we discuss the removal efficiency in terms of adsorption capacity, describe the underlying mechanism behind the adsorption capacity of ZIF-8, present a sustainable synthesis approach, and make vital suggestions to aid in the future application of ZIF-8 for the removal of heavy metals.