Application of a new metal-organic framework of [Ni2F2(4,4'-bipy)2(H2O)2](VO3)2.8H2O as an efficient adsorbent for removal of Congo red dye using experimental design optimization

Adsorption efficacy of functionalized Cu-BDC MOFs tethered 2-mercaptobenzimidazole analogue: A comparative study

A novel metal-organic framework [MOFs], and 2-[benzo [d]thiazol-2-ylthio)-3-hydroxy acrylaldehyde-Cu-benzene dicarboxylic acid was synthesized by solvothermal method and characterized using p-XRD, FSEM-EDX, TGA, BET, FTIR. The tethered organic linker, 2-[benzo [d]thiazol-2-ylthio)-3-hydroxyacrylaldehyde was commonly known as 2-mercaptobenimidazole analogue [2-MBIA]. Analysis of BET disclosed that addition of 2-MBIA to Cu-benzene dicarboxylic acid [Cu-BDC], reduced the crystallite size from 70.0 nm to 65.90 nm, surface area from 17.95 to 17.02 m² g^-1 and enhances the pore size from 5.84 nm with 0.027 cm³ g^-1 pore volume to 8.74 nm with 0.361 cm³ g^-1 pore volume. Batch experiments were conducted to optimize pH, adsorbent dosage, and, Congo red (CR) concentration. The adsorption percentage of CR on the novel MOFs was 54%. Adsorption kinetic studies revealed that the uptake adsorption capacity at equilibrium was 184.7 mg/g from pseudo-first-order kinetics which gave a good fit with the experimental data. Intraparticle diffusion model explained the process of the adsorption mechanism: diffusion from the bulk solution onto the porous surface of the adsorbent. Freundlich and Sips models were the best fit models of the several non-linear isotherm models. Temkin isotherm suggested the adsorption of CR on MOFs was of an exothermic nature.

A Comprehensive Review on Adsorption, Photocatalytic and Chemical Degradation of Dyes and Nitro-Compounds over Different Kinds of Porous and Composite Materials

Dye and nitro-compound pollution has become a significant issue worldwide. The adsorption and degradation of dyes and nitro-compounds have recently become important areas of study. Different methods, such as precipitation, flocculation, ultra-filtration, ion exchange, coagulation, and electro-catalytic degradation have been adopted for the adsorption and degradation of these organic pollutants. Apart from these methods, adsorption, photocatalytic degradation, and chemical degradation are considered the most economical and efficient to control water pollution from dyes and nitro-compounds. In this review, different kinds of dyes and nitro-compounds, and their adverse effects on aquatic organisms and human beings, were summarized in depth. This review article covers the comprehensive analysis of the adsorption of dyes over different materials (porous polymer, carbon-based materials, clay-based materials, layer double hydroxides, metal-organic frameworks, and biosorbents). The mechanism and kinetics of dye adsorption were the central parts of this study. The structures of all the materials mentioned above were discussed, along with their main functional groups responsible for dye adsorption. Removal and degradation methods, such as adsorption, photocatalytic degradation, and chemical degradation of dyes and nitro-compounds were also the main aim of this review article, as well as the materials used for such degradation. The mechanisms of photocatalytic and chemical degradation were also explained comprehensively. Different factors responsible for adsorption, photocatalytic degradation, and chemical degradation were also highlighted. Advantages and disadvantages, as well as economic cost, were also discussed briefly. This review will be beneficial for the reader as it covers all aspects of dye adsorption and the degradation of dyes and nitro-compounds. Future aspects and shortcomings were also part of this review article. There are several review articles on all these topics, but such a comprehensive study has not been performed so far in the literature.

Recent reports on vanadium based coordination polymers and MOFs

Coordination polymers (CP) and metal-organic frameworks (MOF) have become a topic of immense interest in this century primarily because of the structural diversity that they offer. This structural diversity results in their multifaceted utility in various fields of science and technology such as catalysis, medicine, gas storage or separation, conductivity and magnetism. Their utility inspires a large variety of scientists to engage with them in their scientific pursuit thus creating a buzz around them in the scientific community. Metals capable of forming CPs and MOFs are primarily transition metals. Among them vanadium-based CPs and MOFs demand detailed discussion because of the unique nature of vanadium which makes it stable in many oxidation states and coordination number. Vanadium’s versatility imparts additional structural marvel and usefulness to these CPs and MOFs.

Metal-Organic Frameworks for Wastewater Decontamination: Discovering Intellectual Structure and Research Trends

Due to their simple synthesis method and excellent properties, such as superior adsorption and regeneration capabilities, with a large surface area and tunable pores, metal-organic frameworks (MOFs) have emerged as a suitable option for wastewater treatment. Although an exponential growth in MOF literature has been observed in recent years, conducting a quantitative literature analysis of MOF application in wastewater treatment is a novelty. To fill this gap, a total of 1187 relevant publications were extracted from the Web of Science, published during the last 50 years, and analyzed using bibliometric and content analysis techniques. A bibliometric analysis was conducted to reveal growing publication trends, leading journals, prolific countries, and organizations; whereas, a content analysis was used to highlight key research themes and hot topics in this field. The analyses revealed that there is a strong international collaboration among authors, countries, and organizations. Chemical Engineering Journal, Journal of Hazardous Materials, and Journal of Environmental Chemical Engineering are the most prolific journals in this field. Furthermore, the use of MOFs for removing antibiotics from wastewater was identified as a recent hot topic. In addition, performance enhancements of MOFs, in terms of a higher adsorption capacity and water stability, were identified as topics of great interest. To cater to these issues, the application of graphene, graphene oxides, nanoparticles, and quantum dots was also observed in the research fronts in this field.

Research progress of metal organic frameworks and their derivatives for adsorption of anions in water: A review

Anion pollution in water has become a problem that cannot be ignored. The anion concentration should be controlled below the national emission standard to meet the demand for clean water. Among the methods for removing excess anions in water, the adsorption method has a unique removal performance, and the core of the adsorption method is the adsorbent. In recent years, the emerging metal-organic frameworks (MOFs) have the advantages of adjustable porosity, high specific surface area, diverse functions, and easy modification. They are very competitive in the field of adsorption of liquid anions. This article focuses on the adsorption of fluoride, arsenate, chromate, radioactive anions (ReO₄^-, TcO₄^-, SeO₄^2-/SeO₃^2-), phosphate ion, chloride ion, and other anions by MOFs and their derivatives. The preparation methods of MOFs are introduced in turn, the application of different types of metal-based MOFs to adsorb various anions were discussed in categories with their crystal structure and functional groups. The influence on the adsorption of anions is analyzed, including the more common and special adsorption mechanisms, adsorption kinetics and thermodynamics, and regeneration performance are briefly described. Finally, the current situation of MOFs adsorption of anions is summarized, and the outlook for future development is summarized to provide my own opinions for the practical application of MOFs.

Removal of organic pollutants from aqueous solution using metal organic frameworks (MOFs)-based adsorbents: A review

The development of metal organic frameworks (MOFs) has recently drawn a lot of scientific interest in water treatment due to the unique properties such as tunable porosities, large pore volumes, hierarchical structures, excellent adsorption and regeneration performances. MOFs represent an eco-friendly alternative to conventional adsorbents especially for the adsorptive removal of noxious organic pollutants from aqueous solution. Advanced MOFs' performances are justified by the introduction of functional groups, magnetic moieties, and specific foreign materials onto MOFs. This however leads to increase in the manufacturing costs of MOFs and consequently possess a huge challenge in large-scale applications. This review hence critically discusses the recent progresses in the development of MOFs-based adsorbents for the removal of selected organic pollutants (e.g., dyes, antibiotics and pesticides) from aqueous solution. Furthermore, major interaction mechanisms between MOFs and organic pollutants in response to numerous experimental conditions, such as pH, temperature, coexisting ions are put forward. Finally, some recommendations in support for designing MOFs with improved adsorption performances are also highlighted.

Adsorptive removal of dyes from wastewater using a metal-organic framework: A review

Water pollution from synthetic dyes is a growing environmental concern because many dyes have carcinogenic effects on humans and aquatic life. Adsorption is a widely used technology for the separation and removal of dyes from wastewater. However, the dye removal process using conventional adsorbents is not sufficiently efficient for industrial wastewater. Metal-organic frameworks (MOFs) addresses these drawbacks. MOF showed excellent dye removal and degradation capacity owing to its multifunctionality, water-stability, large surface area, tunable pore size and recyclability. Magnetic MOFs retained excellent performance up to several consecutive cycles. Modified MOFs performed as Fenton-like catalysis process which generated abundant reactive radicals that degraded complex organic dyes into simple and less toxic forms which were further adsorbed onto the MOF. This review systematically compiles in-depth studies on the adsorptive removal of dyes from wastewater, MOF adsorption mechanisms, major influencing factors, to adsorption efficiency of MOFs. While all MOFs adsorb dyes through electrostatic attraction, the type of MOF, presence of functional groups, ligands, and pH significantly control the adsorption mechanism. Before developing an MOF, optimization and upgradation of factors and interaction between available adsorption site and adsorbate is needed. Finally, the prospects and new frontiers of MOFs in sustainable water treatment is discussed.

Deployment of metal-organic frameworks as robust materials for sustainable catalysis and remediation of pollutants in environmental settings

From metal-organic chemistry, metal-organic frameworks (MOFs) are of supreme interest for catalysis and environmental settings. Owing to anthropogenic sources and booming industrial practices, the most challenging issue is increased water pollution and environmental insecurity. For instance, several types of synthetic dyes are toxic up to a certain extent, as emerging organic contaminants (EOCs) pose adverse environmental and potential health consequences. A gradual increase in the contamination sources and unpredictable environmental changes in terms of anthropogenic pollution severely affect both water availability and distribution. Therefore, the treatment of dyes containing wastewater matrices for water resource generation is one of the most important tasks, which must be addressed effectively. With structural tunability, MOFs have been appearing as a robust tool for remediating toxic pollutants from wastewater matrices. Moreover, the promising functionality, structural tunability, robust catalytic attributes, compatibility, large surface area, stability in water, and ease in surface functionalization make MOFs one of the considerable materials of interest. This review work spotlights the present-day progress related to MOFs and their catalytic and adsorptive chemistry for a sustainable environment. Following a brief introduction, the characteristic rendering MOFs, as adsorbents, are given with prominent examples. Next, several synthesis routes as a roadmap to engineer MOFs are discussed. From the applied perspective, the adsorptive and catalytic potentialities of MOFs as given by addressing sustainable mitigation of toxic dyes. The last section of the work illustrates key challenging issues and future directions by considering the suiting importance of MOFs.

Enhanced adsorption of Congo red using chitin suspension after sonoenzymolysis

In the present work, chitin suspensions after enzymolysis and sonoenzymolysis were taken as adsorbents to evaluate the adsorption properties of Congo red (CR) dyes. Compared with untreated chitin suspension, the CR adsorption performance was significantly improved after enzymolysis and even more after sonoenzymolysis. According to different adsorption kinetic and isotherm models, Langmuir isotherm and the pseudo-second order model were more reliable to describe the adsorption process of CR onto different chitin samples and demonstrated a monolayer and favorable physisorption process. What's more, negative values of ΔG (Gibbs free energy change) and the shifts to higher negative values with the temperature increasing from adsorption thermodynamic study proved a spontaneous CR adsorption process. The structural characterization before and after adsorption further verified the physical adsorption between chitin and CR, and a larger specific area and higher porosity of chitin suspension was obtained after sonoenzymolysis with more available active sites.