MIL−53 (Fe) for constructing hydrogenated Fe3O4@C@TiO2 double core-shell nanocrystals as superior bifunctional photocatalyst

A review on titanium oxide nanoparticles modified metal-organic frameworks for effective CO2 conversion and efficient wastewater remediation

Environmental pollution has been increasing since last decade due to increasing industrialisation and urbanisation. Various kinds ofenvironmental pollutants including carbon dioxide (CO2), dyes, pharmaceuticals, phenols, heavy metals along with many organic and inorganic species have been discovered in the various environmental compartments which possess harmful impacts tox human health, wildlife, and ecosystems. Thus, various efforts have been made through regulations, technological advancements, and public awareness campaigns to reduce the impact of the pollution. However, finding suitable alternatives to mitigate their impacts remained a challenge. Metal-organic frameworks (MOFs) are one of the advanced materials with unique features such as high porosity and stability which exhibit versatile applications in environmental remediation. Their composites with titanium oxide nanoparticles (TiO2) have been discovered to offer potential feature such as light harvesting capacity and catalytic activity. The composite integration and properties have been confirmed through characterization using surface area analysis, scanning electron/transmission electron microscopy, atomic force microscopy, fourier transformed infrared spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, and others. Thus, this work rigorously discussed potential applications of the MOF@TiO2 nanomaterials for the CO2 capture and effective utilization in methanol, ethanol, acetone, acetaldehyde, and other useful products that served as fuel to various industrial processes. Additionally, the work highlights the effective performance of the materials towards photocatalytic degradation of both organic and inorganic pollutants with indepth mechanistic insights. The article will offer significant contribution for the development of sustainable and efficient technologies for the environmental monitoring and pollution mitigation.

Bifunctional of Fe3O4@chitosan nanocomposite as a clarifying agent and cationic flocculant on different sugar solutions as a comprehensive semi industrial application

In the sugar industry, eliminating side impurities throughout the manufacturing process is the most significant obstacle to clarifying sugar solutions. Herein, magnetic chitosan (MCS) nanocomposite was Fabricated to be used as a biodegradable, environmentally friendly clarifying agent throughout the cane juice and sugar refining processes. Fe3O4 was synthesized using the coprecipitation procedure, and then MCS was combined using a cross-linking agent. Furthermore, 14.76 emu g-1 was the maximum saturation magnetization (Ms) value. Because MCS is magnetically saturated, it may be possible to employ an external magnetic field to separate the contaminant deposited on its surface. Additionally, zeta potential analysis showed outstanding findings for MCS with a maximum value of (+) 20.7 mV, with improvement in color removal % up to 44.8% using MCS with more than 24% in color removal % compared to the traditional clarification process. Moreover, utilizing MCS reduced turbidity from 167 to 1 IU. Overall, we determined that MCS nanocomposite exhibits considerable effectiveness in the clarifying process for different sugar solutions, performing as an eco-friendly bio-sorbent and flocculating material.

Interface Coordination Engineering of P-Fe3O4/Fe@C Derived from an Iron-Based Metal Organic Framework for pH-Universal Water Splitting

Developing electrocatalysts with high energy conversion efficiency is urgently needed. In this work, P-Fe₃O₄/Fe@C electrodes with rich under-coordinated Fe atom interfaces are constructed for efficient pH-universal water splitting. The introduction of under-coordinated Fe atoms into the P-Fe₃O₄/Fe@C interface can increase the local charge density and polarize the 3d orbital lone electrons, which promotes water adsorption and activation to release more H^*, thus elevating electrocatalytic activity. As a donor-like catalyst, P-Fe₃O₄/Fe@C displays excellent electrocatalytic performance with overpotentials of 160 mV and 214 mV in acidic and alkaline electrolytes at 10 mA cm^-2, in addition to pH-universal long-term stability.

Metal chalcogenides (CuS or MoS2)-modified TiO2 as highly efficient bifunctional photocatalyst nanocomposites for green H2 generation and dye degradation

Herein, we report the modification of TiO₂ nanostructures with two different metal chalcogenides (CuS or MoS₂). The effect of the preparation scheme (hydrothermal and coprecipitation methods) and the mass ratio of metal chalcogenides were investigated. The as-synthesized photocatalyst nanocomposites were fully characterized by various techniques. Moreover, the photo/electrochemical analysis were performed to investigate the photoelectric properties and photocatalytic mechanism. The photocatalytic performance was evaluated using two test reactions. In the case of H₂ generation via water splitting, it was found that 0.5 wt% CuS-TiO₂ synthesized via the coprecipitation method exhibited an initial hydrogen evolution rate (HER) of 2.95 mmol h^-1 g^-1. While, the optimized 3 wt% MoS₂-TiO₂ synthesized by the hydrothermal method, showed an HER of 1.7 mmol h^-1 g^-1. Moreover, the degradation efficiency of methylene blue dye was 98% under UV-Vis light irradiation within 2 h over 0.5 CT_PP and 3MT_HT. Under visible irradiation, the degradation efficiency was 100% and 96% for 3MT_PP and 0.5CT_HT in the presence of H₂O₂, respectively. This study has proven that metal chalcogenides can act as effective, stable, and low-cost bifunctional co-catalysts to enhance the overall photocatalytic performance.

Efficient upcycling of iron scrap and waste polyethylene terephthalate plastic into Fe3O4@C incorporated MIL-53(Fe) as a novel electro-Fenton catalyst for the degradation of salicylic acid

The current research demonstrates the efficiency of a low-cost MIL-53(Fe)-metal-organic framework (MOF) derived Fe₃O₄@C (MIL-53(Fe)@Fe₃O₄@C) electrocatalyst in a batch-scale electro-Fenton (EF) process for the degradation of salicylic acid (SA) from wastewater. The electrocatalyst was prepared from the combination of polyethylene terephthalate (PET) and iron scrap wastes. The result showed 91.68 ± 3.61% degradation of 50 mg L^-1 of SA under optimum current density of 5.2 mA cm^-2, and pH of 7.0 during 180 min of electrolysis time. The degradation of SA from waste catalyst was similar to the chemical-based MIL-53(Fe)-derived Fe₃O₄@C (cFe) cathode catalyst. The presence of chloride ions (Cl^-) in the water matrix has shown a strong inhibitory effect on the elimination of SA, followed by nitrate (NO₃^-), and bicarbonate (HCO₃^-) ions. The multiple cyclic voltammetry (CV) analysis and reusability test of waste cathode catalyst showed only 8.03% drop of current density at the end of the 20th cycle and 5% drop of degradation efficiency after 6th cycle with low leaching of iron. The radical scavenging experiment revealed that the HO^• generated via electrochemical generation of H₂O₂ had a prominent contribution in the removal of SA compared to HO₂^•/O₂^•-. Besides, possible catalysis mechanism and degradation pathways were deduced. Furthermore, a satisfactory performance in the treatment of SA spiked in real water matrices was also observed by waste-derived Fe₃O₄@C cathode catalyst (wFe). Additionally, the total operating cost and toxicity analysis showed that the as-synthesized wFe cathode catalyst could be appropriate for removing organic pollutants from wastewater in the large-scale application.

Synthesis, characterization and application of high adsorption performance of novel 1,4-polyketone

This study aims to develop an alternating polyketone containing cationic groups in one and four alternating positions for increased functionality. A novel polyarylidene ketone was synthesized using simple condensation polymerization of terephthaldehyde and 2,5-hexane dione (PAK) The physicochemical properties of the resulting polymer were evaluated using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, UV-Visible absorbance, fluorescence, and SEM investigations. The findings show that the polymer is amorphous, has good thermal stability, and emits red light. It can also be used as a dye adsorbent in aqueous solutions, with high selectivity for the cationic dye methylene blue (MB). The adsorbent efficiency of PAK was measured as a function of pH, dosage, and initial dye concentration; the greatest dye removal of 96 % was obtained at pH 10, 50 mg dosage, and initial dye concentration of 20 ppm. Kinetics and isotherms were studied, showing that the pseudo-second-order model described kinetic data better than Freundlich and Langmuir and revealed a satisfactory chemisorption process. This study suggests that PAK can purify MB dyeing wastewater, remove Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Cd²⁺, Fe³⁺ metal ions well, and is selective for Fe³⁺ and Cu²⁺; ion adsorption is chelating-based.