New hybrid nanocomposite of copper terephthalate MOF-graphene oxide: synthesis, characterization and application as adsorbents for toxic metal ion removal from Sungun acid mine drainage

Heavy metal sequestration from wastewater by metal-organic frameworks: a state-of-the-art review of recent progress

Metal-organic frameworks (MOFs) have emerged as highly promising adsorbents for removing heavy metals from wastewater due to their tunable structures, high surface areas, and exceptional adsorption capacities. This review meticulously examines and summarizes recent advancements in producing and utilizing MOF-based adsorbents for sequestering heavy metal ions from water. It begins by outlining and contrasting commonly employed methods for synthesizing MOFs, such as solvothermal, microwave, electrochemical, ultrasonic, and mechanochemical. Rather than delving into the specifics of adsorption process parameters, the focus shifts to analyzing the adsorption capabilities and underlying mechanisms against critical metal(loid) ions like chromium, arsenic, lead, cadmium, and mercury under various environmental conditions. Additionally, this article discusses strategies to optimize MOF performance, scale-up production, and address environmental implications. The comprehensive review aims to enhance the understanding of MOF-based adsorption for heavy metal remediation and stimulate further research in this critical field. In brief, this review article presents a comprehensive overview of the contemporary information on MOFs as an effective adsorbent and the challenges being faced by these adsorbents for heavy metal mitigation (including stability, cost, environmental issues, and optimization), targeting to develop a vital reference for future MOF research.

Progressive Insights into Metal-Organic Frameworks and Metal-Organic Framework-Membrane Composite Systems for Wastewater Management

The sustainable management of wastewater through recycling and utilization stands as a pressing concern in the trajectory of societal advancement. Prioritizing the elimination of diverse organic contaminants is paramount in wastewater treatment, garnering significant attention from researchers worldwide. Emerging metal-organic framework materials (MOFs), bridging organic and inorganic attributes, have surfaced as novel adsorbents, showcasing pivotal potential in wastewater remediation. Nevertheless, challenges like limited water stability, elevated dissolution rates, and inadequate hydrophobicity persist in the context of wastewater treatment. To enhance the performance of MOFs, they can be modified through chemical or physical methods, and combined with membrane materials as additives to create membrane composite materials. These membrane composites, derived from MOFs, exhibit remarkable characteristics including enhanced porosity, adjustable pore dimensions, superior permeability, optimal conductivity, and robust water stability. Their ability to effectively sequester organic compounds has spurred significant research in this field. This paper introduces methods for enhancing the performance of MOFs and explores their potential applications in water treatment. It delves into the detailed design, synthesis strategies, and fabrication of composite membranes using MOFs. Furthermore, it focuses on the application prospects, challenges, and opportunities associated with MOF composite membranes in water treatment.

Study of the synthesis, adsorption property, and photocatalytic activity of TiO2/coal gasification fine slag mesoporous silica glass microsphere composite

In this study, TiO₂/MSGM composite material with adsorption-photocatalytic properties was prepared by extracting mesoporous silica glass microsphere (MSGM) from coal gasification fine slag (CGFS) as a novel TiO₂ carrier. The results of characterization and properties of the composite showed that MSGM could improve the adsorption capacity and photocatalytic activity of the composite by improving the pore structure of the composite, hindering the growth of TiO₂ particles, increasing the phase transition temperature of TiO₂, enhancing the dispersion of TiO₂ particles. The sample 1:3-TiO₂/MSGM-2-500 prepared under the optimized conditions possesses satisfactory morphology characteristics, high adsorption capacity, and photocatalytic activity to rhodamine B (RhB). The synergistic effects of adsorption and photocatalytic significantly increase the total removal rate of RhB. This study not only provides a new direction for high-value-added resource utilization of CGFS but also gives a new kind of low-cost carrier material with adsorption property for TiO₂ loading to remove organic dye pollutants.

Graphene-Based Metal-Organic Framework Hybrids for Applications in Catalysis, Environmental, and Energy Technologies

Current energy and environmental challenges demand the development and design of multifunctional porous materials with tunable properties for catalysis, water purification, and energy conversion and storage. Because of their amenability to de novo reticular chemistry, metal-organic frameworks (MOFs) have become key materials in this area. However, their usefulness is often limited by low chemical stability, conductivity and inappropriate pore sizes. Conductive two-dimensional (2D) materials with robust structural skeletons and/or functionalized surfaces can form stabilizing interactions with MOF components, enabling the fabrication of MOF nanocomposites with tunable pore characteristics. Graphene and its functional derivatives are the largest class of 2D materials and possess remarkable compositional versatility, structural diversity, and controllable surface chemistry. Here, we critically review current knowledge concerning the growth, structure, and properties of graphene derivatives, MOFs, and their graphene@MOF composites as well as the associated structure-property-performance relationships. Synthetic strategies for preparing graphene@MOF composites and tuning their properties are also comprehensively reviewed together with their applications in gas storage/separation, water purification, catalysis (organo-, electro-, and photocatalysis), and electrochemical energy storage and conversion. Current challenges in the development of graphene@MOF hybrids and their practical applications are addressed, revealing areas for future investigation. We hope that this review will inspire further exploration of new graphene@MOF hybrids for energy, electronic, biomedical, and photocatalysis applications as well as studies on previously unreported properties of known hybrids to reveal potential "diamonds in the rough".

Adsorption characteristics of Pb(II), Cd(II) and Cu(II) on carbon nanotube-hydroxyapatite

Based on batch experiments, we investigate the adsorption characteristics of Pb(II), Cd(II) and Cu(II) on multi-walled carbon nanotube-hydroxyapatite (MWCNT-HAP) composites in detail and explore the effects of the solid-to-liquid ratio, pH, the ionic strength, reaction time and temperature on adsorption. The results show that the adsorption on MWCNT-HAP follows Pb(II)>Cu(II)>Cd(II). With an increasing solid-to-liquid ratio, the adsorption quantity of Pb(II), Cd(II) and Cu(II) on MWCNT-HAP decreases, whereas the removal efficiency increases. The optimal pH for adsorption is 4.0∼6.0. The effect of the ionic strength on the adsorption of Cd(II) is pronounced, whereas that on the adsorption of Pb(II) and Cu(II) is small. In the single-component system and ternary-component system, the adsorption processes for Pb(II), Cd(II) and Cu(II) on MWCNT-HAP have fast kinetics, and the pseudo-second-order kinetics model can well describe the adsorption kinetics of the three heavy metals. The adsorption of Pb(II), Cd(II) and Cu(II) on MWCNT-HAP is spontaneous and endothermic, and the Langmuir model can well simulate the isothermal adsorption of Pb(II) and Cu(II), whereas the Langmuir and Freundlich models can be used to describe the isothermal adsorption of Cd(II).

Recent progress in metal-organic framework/graphene-derived materials for energy storage and conversion: design, preparation, and application

Graphene or chemically modified graphene, because of its high specific surface area and abundant functional groups, provides an ideal template for the controllable growth of metal-organic framework (MOF) particles. The nanocomposite assembled from graphene and MOFs can effectively overcome the limitations of low stability and poor conductivity of MOFs, greatly widening their application in the field of electrochemistry. Furthermore, it can also be utilized as a versatile precursor due to the tunable structure and composition for various derivatives with sophisticated structures, showing their unique advantages and great potential in many applications, especially energy storage and conversion. Therefore, the related studies have been becoming a hot research topic and have achieved great progress. This review summarizes comprehensively the latest methods of synthesizing MOFs/graphene and their derivatives, and their application in energy storage and conversion with a detailed analysis of the structure-property relationship. Additionally, the current challenges and opportunities in this field will be discussed with an outlook also provided.

Recent Advances in Applications of Hybrid Graphene Materials for Metals Removal from Wastewater

The presence of traces of heavy metals in wastewater causes adverse health effects on humans and the ecosystem. Adsorption is a low cost and eco-friendly method for the removal of low concentrations of heavy metals from wastewater streams. Over the past several years, graphene-based materials have been researched as exceptional adsorbents. In this review, the applications of graphene oxide (GO), reduce graphene oxide (rGO), and graphene-based nanocomposites (GNCs) for the removal of various metals are analyzed. Firstly, the common synthesis routes for GO, rGO, and GNCs are discussed. Secondly, the available literature on the adsorption of heavy metals including arsenic, lead, cadmium, nickel, mercury, chromium and copper using graphene-based materials are reviewed and analyzed. The adsorption isotherms, kinetics, capacity, and removal efficiency for each metal on different graphene materials, as well as the effects of the synthesis method and the adsorption process conditions on the recyclability of the graphene materials, are discussed. Finally, future perspectives and trends in the field are also highlighted.

Metal-organic frameworks/carbon-based materials for environmental remediation: A state-of-the-art mini-review

In recent years, many research groups started to study the combination of metal-organic frameworks (MOFs) with nanocarbon materials, which showed the excellent improved performances than MOFs alone. The addition of carbon materials such as graphene oxides (GOs) and carbon nanotubes (CNTs) into MOFs can improve the physico-chemical properties of parent MOFs with excellent chemical robustness, high mechanical and distinguished electronic thermal robustness. These advantages facilitate the wider applications of MOFs/carbon materials (MOFs-C) in more research fields. This paper is devoted to reviewing the recent studies about the preparation and applications of MOFs-C in environmental remediation. This paper discusses the efficient adsorptive removal of a wide range of pollutants by MOFs-C, including organic contaminants and heavy metals from water as well as VOCs and some other toxic gases from atmospheric environment. Additionally, the catalytic performance of these nanocomposites for photocatalysis and Fenton-like oxidation of water pollutants is discussed in details. Meanwhile, the significant roles of nanocarbons and in-depth mechanisms for improved adsorption or catalysis are summarized. Finally, future perspectives on the development and application of MOFs-C composites for pollution remediation are presented at the end of this paper.

Self-assembled three-dimensional double network graphene oxide/polyacrylic acid hybrid aerogel for removal of Cu2+ from aqueous solution

Three-dimensional (3D) double network graphene oxide/polyacrylic acid (GO/PAA) hybrid aerogels were fabricated under mild conditions from the mixture of GO and acrylic acid (AA) monomers using a one-pot in situ solution polymerization process which included the polymerization of AA and the self-assembly of functional GO sheets. The PAA chains served as not only binder to assemble GO sheets into 3D framework but also modifier to provide more active functional groups. The adsorbents based on such material exhibited superior adsorption performance towards Cu²⁺ ions in aqueous media due to rich mesopores, high specific surface area, and abundant active sites. This work brings a new vision for assembling 3D porous graphene-based nanomaterials as adsorbents in environmental protection.