Studies on the removal of phosphate in water through adsorption using a novel Zn-MOF and its derived materials

Metal-Organic Frameworks-Derived Nanocarbon Materials and Nanometal Oxides for Photocatalytic Applications

Harnessing low-density solar energy and converting it into high-density chemical energy through photocatalysis has emerged as a promising avenue for the production of chemicals and remediation of environmental pollution, which contributes to alleviating the overreliance on fossil fuels. In recent years, metal-organic frameworks (MOFs) have gained widespread application in the field of photocatalysis due to their photostability, tunable structures, and responsiveness in the visible light range. However, most MOFs exhibit relatively low response to light, limiting their practical applications. MOFs-derived nanomaterials not only retain the inherent advantages of pristine MOFs but also show enhanced light adsorption and responsiveness. This review categorizes and summarizes MOFs-derived nanomaterials, including nanocarbons and nanometal oxides, providing representative examples for the synthetic strategies of each category. Subsequently, the recent research progress on MOFs-derived materials in photocatalytic applications are systematically introduced, specifically in the areas of photocatalytic water splitting to H2, photocatalytic CO2 reduction, and photocatalytic water treatment. The corresponding mechanisms involved in each photocatalytic reaction are elaborated in detail. Finally, the review discusses the challenges and further directions faced by MOFs-derived nanomaterials in the field of photocatalysis, highlighting their potential role in advancing sustainable energy production and environmental remediation.

Selective Phosphate Adsorption Using Topologically Regulated Binary-Defect Metal-Organic Frameworks: Essential Role of Interfacial Electron Mobility

Metal-organic framework (MOF)-modified biochars (BC) have gained recognition as potent adsorbents for phosphate. However, essential insights into the electronic interfacial state of the MOFs remain lacking. In this study, we propose a novel topological transformation strategy to directionally regulate the interfacial electronic states of BC/MOFs composites. The optimized BC/MOFs exhibited an excellent selective phosphate adsorption capacity of 188.68 mg·g-1, coupled with rapid sorption kinetics of 6.81 mg·(g·min0.5)-1 in simulated P-laden wastewater. When challenged with real bioeffluent, such efficacy was still maintained (5 mg·L-1, 25.92 mg·g-1). This superior performance was due to the Fe(III) → Fe(II) transition, promoting electron mobility and leading to the anchoring of Mg(II) to form specific coordination unsaturated sites (Mg-CUS) for phosphate adsorption. Importantly, the simultaneous regulation of binary defects further enhances electron mobility, resulting in the formation of sp3 unequal hybrid orbitals with a stronger internal coupling capability between Mg 3s in Mg-CUS and O 2p in phosphate. Furthermore, the high electron affinity of Mg effectively promotes electron cycling, endowing BC/MOFs with a distinct self-healing capability to facilitate phosphate desorption. The outcomes of this study provide novel perspectives for electronic regulated phosphate adsorption.

Highlights in Interface of Wastewater Treatment by Utilizing Metal Organic Frameworks: Purification and Adsorption Kinetics

Polluted water has become a concern for the scientific community as it causes many severe threats to living beings. Detection or removal of contaminants present in wastewater and attaining purity of water that can be used for various purposes are a primary responsibility. Different treatment methods have already been used for the purification of sewage. There is a need for low-cost, highly selective, and reusable materials that can efficiently remove pollutants or purify contaminated water. In this regard, MOFs have shown significant potential for applications such as supercapacitors, drug delivery, gas storage, pollutant adsorption, etc. The outstanding structural diversity, substantial surface areas, and adjustable pore sizes of MOFs make them superior candidates for wastewater treatment. This Review provides an overview of the interaction science and engineering (kinetic and thermodynamic aspects with interactions) underpinning MOFs for water purification. First, fundamental strategies for the synthesis methods of MOFs, different categories, and their applicability in wastewater treatment are summarized, followed by a detailed explanation of various interaction mechanisms. Finally, current challenges and future outlooks for research on MOF materials toward the adsorption of hazardous components are discussed. A new avenue for modifying their structural characteristics for the adsorption and separation of hazardous materials, which will undoubtedly direct future work, is also summarized.

Phosphorus removal from water by the metal-organic frameworks (MOFs)-based adsorbents: A review for structure, mechanism, and current progress

Efficacious phosphate removal is essential for mitigating eutrophication in aquatic ecosystems and complying with increasingly stringent phosphate emission regulations. Chemical adsorption, characterized by simplicity, prominent treatment efficiency, and convenient recovery, is extensively employed for profound phosphorus removal. Metal-organic frameworks (MOFs)-derived metal/carbon composites, surpassing the limitations of separate components, exhibit synergistic effects, rendering them tremendously promising for environmental remediation. This comprehensive review systematically summarizes MOFs-based materials' properties and their structure-property relationships tailored for phosphate adsorption, thereby enhancing specificity towards phosphate. Furthermore, it elucidates the primary mechanisms influencing phosphate adsorption by MOFs-based composites. Additionally, the review introduces strategies for designing and synthesizing efficacious phosphorus capture and regeneration materials. Lastly, it discusses and illuminates future research challenges and prospects in this field. This summary provides novel insights for future research on superlative MOFs-based adsorbents for phosphate removal.

Facile Synthesis of Ce-MOF for the Removal of Phosphate, Fluoride, and Arsenic

Ce-MOF was synthesized by a solvothermal synthesis method and was used to simultaneously remove phosphate, fluoride and arsenic (V) from water by adsorption. Ce-MOF was characterized by a nitrogen adsorption-desorption isotherm, scanning electron microscopy, and infrared spectroscopy. The effects of initial concentration, adsorption time, adsorption temperature, pH value and adsorbent on the adsorption properties were investigated. A Langmuir isotherm model was used to fit the adsorption data, and the adsorption capacity of phosphate, fluoride, and arsenic (V) was calculated to be 41.2 mg·g-1, 101.8 mg·g-1 and 33.3 mg·g-1, respectively. Compared with the existing commercially available CeO2 and other MOFs, Ce-MOF has a much higher adsorption capacity. Furthermore, after two reuses, the performance of the adsorbent was almost unchanged, indicating it is a stable adsorbent and has good application potential in the field of wastewater treatment.

Nanoscale designing of metal organic framework moieties as efficient tools for environmental decontamination

Environmental pollutants, being a major and detrimental component of the ecological imbalance, need to be controlled. Serious health issues can get intensified due to contaminants present in the air, water, and soil. Accurate and rapid monitoring of environmental pollutants is imperative for the detoxification of the environment and hence living beings. Metal-organic frameworks (MOFs) are a class of porous and highly diverse adsorbent materials with tunable surface area and diverse functionality. Similarly, the conversion of MOFs into nanoscale regime leads to the formation of nanometal-organic frameworks (NMOFs) with increased selectivity, sensitivity, detection ability, and portability. The present review majorly focuses on a variety of synthetic methods including the ex situ and in situ synthesis of MOF nanocomposites and direct synthesis of NMOFs. Furthermore, a variety of applications such as nanoabsorbent, nanocatalysts, and nanosensors for different dyes, antibiotics, toxic ions, gases, pesticides, etc., are described along with illustrations. An initiative is depicted hereby using nanostructures of MOFs to decontaminate hazardous environmental toxicants.

Enhanced phosphate adsorption studies on several metal-modified aluminum sludge: preparation optimization, adsorption behavior, and mechanistic insight

To solve the problems such as water eutrophication caused by excess phosphorus, the potential residual value of aluminum sludge was fully exploited and its phosphate adsorption capacity was further improved. In this study, twelve metal-modified aluminum sludge materials were prepared by co-precipitation method. Among them, Ce-WTR, La-WTR, Y-WTR, Zr-WTR, and Zn-WTR showed excellent adsorption capacity for phosphate. The adsorption performance of Ce-WTR on phosphate was twice that of the native sludge. The enhanced adsorption mechanism of metal modification on phosphate was investigated. The characterization results showed that the increase in specific surface area after metal modification was 9.64, 7.5, 7.29, 3, and 1.5 times, respectively. The adsorption of phosphate by WTR and Zn-WTR was in the accordance with Langmuir model, while the others were more following the Freundlich model (R² > 0.991). The effects of dosage, pH, and anion on phosphate adsorption were investigated. The surface hydroxyl groups and metal (hydrogen) oxides played an important role in the adsorption process. The adsorption mechanism involves physical adsorption, electrostatic attraction, ligand exchange, and hydrogen bonding. This study provides new ideas for the resource utilization of aluminum sludge and theoretical support for preparing novel adsorbents for efficient phosphate removal.

Novel Carbazole-Based Porous Organic Polymer for Efficient Iodine Capture and Rhodamine B Adsorption

A new porous organic polymer (CTF-CAR), which takes carbazole as the electron-rich center unit and thiophenes as the auxiliary group, has been synthesized through catalyst-free Schiff-base polymerization. At the same time, the structure, thermal stability, morphology, and other basic properties of the polymer were analyzed by IR, NMR, TGA, and SEM. Then, CTF-CAR was applied to iodine capture and rhodamine B adsorption. Due to its strong electron donor ability and abundant heteroatom binding sites, which have a positive effect on the interaction between the polymer network and adsorbates, CTF-CAR exhibits high uptake capacities for iodine vapor and rhodamine B as 2.86 g g-1 and 199.7 mg g-1, respectively. The recyclability test also confirmed that it has good reusability. We found that this low-cost and catalyst-free synthetic porous organic polymer has great potential for the treatment of polluted water and iodine capture.

Recent advances on bimetallic metal-organic frameworks (BMOFs): Syntheses, applications and challenges

Bimetallic metal-organic frameworks (MOFs) possess two different metal ions as nodes in their molecular frameworks. They are prepared by either using one-pot syntheses wherein different metals are mixed with suitable...