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.

In this study, a series of g-C₃N₄ nanosheets were prepared by various thermal oxidative etching times from four different precursors (urea, melamine, dicyandiamide and thiourea). The physicochemical properties of these g-C₃N₄ nanosheets were analyzed in detail using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence emission spectra, Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis and ultraviolet-visible diffuse reflectance. The results revealed that the g-C₃N₄ nanosheets obtained a thinner layer thickness and larger specific surface area, with an extension of thermal oxidative etching time. Meanwhile, sulfamethazine (SMZ), one of the most widely used sulfonamides, was used to evaluate the photocatalyst activity of the g-C₃N₄ nanosheets prepared in this study. Compared to other g-C₃N₄ nanosheets, urea-derived g-C₃N₄ nanosheets under 330 min thermal oxidative etching showed the highest photocatalytic activity for SMZ under visible light. In conclusion, our study provides detailed insights into the synthesis and characterization of g-C₃N₄ nanosheets prepared from various precursors and highlights the importance of thermal oxidative etching time in determining the photocatalytic activity of these materials.

CWMFC is a novel technology that has been used for almost a decade for concurrent wastewater treatment and electricity generation in varying scopes of domestic, municipal, and industrial applications since its implementation in 2012. Its advantage of low-cost enhanced wastewater treatment and sustainable bioelectricity generation has gained considerable attention. Nevertheless, the overall efficiency of this novel technology is inclined by several operating factors and configuration strands, such as pH, sewage composition, organic loading, electrode material, filter media, electrogens, hydraulic retention time, and macrophytes. Here, we investigate the effect of the wetland plant component on the overall performance of CWMFCs. The macrophyte’s involvement in the oxygen input, nutrient uptake, and direct degradation of pollutants for the required treatment effect and bioelectricity production are discussed in more detail. The review identifies and compares planted and unplanted CWMFC with their efficiency on COD removal and electricity generation based on previous and recent studies.

Water pollution, driven by industrial wastewater, agricultural runoff, and domestic sewage, introduces organic pollutants (e.g., dyes and antibiotics) and heavy metal ions (e.g., Pb²⁺ and Cr(VI)), threatening ecosystems and human health. Although traditional water treatment technologies have now matured, they still have some deficiencies in terms of specific pollutants. Metal–organic frameworks (MOFs), particularly zeolite imidazole frame-67 (ZIF-67)—a cobalt-based MOF with high surface area, tunable pores, and robust chemical stability—show excellent adsorption capacity for pollutants and have emerged as promising candidates for water treatment due to their efficacy in adsorption, catalysis, and photocatalysis. This review examines ZIF-67’s synthesis, functionalization strategies, and applications in removing organic pollutants and heavy metals. It explores its mechanisms, composite designs, and recyclability, while highlighting challenges and future directions for developing efficient, sustainable water treatment technologies.

Metal–organic frameworks (MOFs) have garnered significant attention for water purification in recent years. In particular, UiO-66 (a member of the UiO-MOF family, developed at the University of Oslo) has emerged as a promising water purification material. UiO-66 exhibits excellent adsorption through electrostatic interaction, π–π stacking and Lewis acid–base coordination mechanisms. The photocatalytic degradation property was enhanced through metal doping, composite with semiconductor materials, defect engineering, etc., and the removal efficiency of pollutants was significantly improved. This review systematically describes the structure of UiO-66 and the synthesis methods of UiO-66, including solvothermal, microwave-assisted, mechanized and electrochemical methods, as well as the application of UiO-66 in the adsorption and photocatalytic degradation of various pollutants.