A new environmentally sound and low-cost yet highly efficient pyroxene nanoparticles employed for the first time as nanoadsorbents for violanthrone-79.

The growing accumulation of emerging contaminants in the environment can cause direct and indirect water pollution that puts human lives at risk. The fact that these contaminants are not or cannot be eliminated from the municipal water utilities, poses a significant concern. Researchers are currently pulling massive attention to improve existing technologies, develop new strategies, and provide environmentally durable solutions to mitigate water contamination problems. Adsorption and photodegradation are two of the most sustainable technologies that are used in water purification. These technologies have many advantages because of the economic, simple, and easily operated designs needed to treat wastewater. Within these applications, metal organic frameworks (MOFs) are playing a significant role as novel class of porous materials characterized by a crystalline structure. MOFs are considered good candidates to be employed in wastewater treatment technologies because of the tunability of their features. The scope of this review article is to provide a comprehensive description of the recent studies published in the literature about the adsorptive and photocatalytic use of MOFs for the removal of organic emerging contaminants from wastewater. Furthermore, this study briefly highlights the synthesis technologies of MOFs. Finally, future perspective and challenges associated with MOF large-scale production are discussed.

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The nanosize effects of NiO nanosorbcats on adsorption and post‐adsorption catalytic thermo‐oxidative decomposition of vacuum residue (VR) n‐C5 asphaltenes was investigated using a UV‐vis spectrophotometer and thermogravimetric analyzer coupled with a mass spectrometer. Sizes between 5 and 80 nm of different‐sized NiO nanosorbcats were employed. Batch adsorption experiments were carried out for the considered asphaltenes in toluene solutions, monitored via UV‐vis spectrophotometry. The macroscopic adsorption isotherms were described by implementing the solid‐liquid equilibrium (SLE) model. The findings showed that thermally cracked vacuum residue (VR) n‐C5 asphaltenes interact to different extents with different‐sized NiO nanosorbcats. A normalized surface area basis was used for the amount of VR n‐C5 asphaltene adsorbed per nm2 of NiO surface, which was the highest for NiO nanoparticles of size 80 nm, with 5 nm size being the lowest. Thermogravimetric analysis of VR n‐C5 asphaltenes was also achieved and the reaction products were explored by a mass spectrometer. The Kissinger‐Akahira‐Sunose (KAS) isoconversional model was used to describe the reaction mechanism and to confirm the validity of the catalytic role of the different particle sizes of NiO nanosorbcats. The highest catalytic activity was for smallest NiO when compared to the highest NiO nanosorbcats. Furthermore, the results of thermodynamic transition state parameters of activation; changes in Gibbs free energy (ΔG‡), entropy (ΔS‡), and enthalpy (ΔH‡) highlighted the catalytic activity of NiO nanosorbcats towards VR n‐C5 asphaltenes oxidation. These findings exhibit the significance of textural properties and nanosize of nanoparticles during adsorption and thermal catalytic processing of asphaltenes.

The catalytic properties of a simple iron-containing MOF based on fumaric acid, MIL-88A, were investigated in the ketalization of ethyl levulinate with glycerol. The corresponding product is a component of current interest as a renewable building block for many uses. Under the following conditions (solventless, 120 °C, stoichiometric ratio, 1% cat.), the reaction proceeds with good yields (85%), and the catalyst can be recovered and recycled without loss of activity, despite some changes in the crystalline lattice and morphology. Moreover, the residual iron content in the product is in the order of units of ppm (≤2), which demonstrates the robustness of the MOF under the reaction conditions.

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Silica-based NiO and MgO nanosorbcats (SBNs) for competitive adsorption of methylene blue and acid red 88.

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