Dopamine Grafted Iron-Loaded Waste Silk for Fenton-Like Removal of Toxic Water Pollutants

Preparation of Fe3O4@CA/BNNS/AgNP Magnetic Microspheres and Photocatalysis of Dyes

In this work, sea urchin-like magnetic Fe3O4@CA/BNNS/AgNP composite microspheres were successfully prepared. The photocatalytic performance of composite microspheres for the organic dye rhodamine B (RhB) was systematically investigated under different conditions, and the catalytic degradation rate of RhB was as high as 95% within 60 min; after three cycles of recycling, the degradation rate of RhB was reduced by only 8%. The main active agents in the reaction are e- and •O2-. Fe3O4@CA/BNNS/AgNP microspheres prepared in this study exhibit photocatalytic and electrochemical properties, making them easy to separate. This work is not limited to the development of Fe3O4-based catalysts but also is expected to provide ideas for the research and progress of photocatalytic composite catalysts with electrochemical properties.

Fe-Immobilised Catechol-Based Hypercrosslinked Polymer as Heterogeneous Fenton Catalyst for Degradation of Methylene Blue in Water

Clean water is one of the sustainable development goals. Organic dye is one of the water pollutants affecting water quality. Hence, the conversion of dyes to safer species is crucial for water treatment. The Fenton reaction using Fe as a catalyst is a promising process. However, homogeneous catalysts are normally sensitive, difficult to separate, and burdensome to reuse. Therefore, a catechol-based hypercrosslinked polymer (catechol-HCP) was developed as an inexpensive solid support for Fe (catechol-HCP-Fe) and applied as a heterogenous Fenton catalyst. The good interaction of the catechol moiety with Fe, as well as the porous structure, simple preparation, low cost, and high stability of catechol-HCP, make it beneficial for Fe-loading in the polymer and Fenton reaction utilisation. The catechol-HCP-Fe demonstrated good catalytic activity for methylene blue (MB) degradation in a neutral pH. Complete decolouration of 100 ppm MB could be observed within 25 min. The rate of reaction was influenced by H₂O₂ concentration, polymer dose, MB concentration, pH, and temperature. The catechol-HCP-Fe could be reused for at least four cycles. The dominant reactive species of the reaction was considered to be singlet oxygen (¹O₂), and the plausible mechanism of the reaction was proposed.

Appealing Renewable Materials in Green Chemistry

In just a few years, chemists have significantly changed their approach to the synthesis of organic molecules in the laboratory and industry. Researchers are encouraged to approach “greener” reagents, solvents, and methodologies, to go hand in hand with the world’s environmental matter, such as water, soil, and air pollution. The employment of plant and animal derivates that are commonly regarded as “waste material” has paved the way for the development of new green strategies. In this review, the most important innovations in this field have been highlighted, paying due attention to those materials that have played a crucial role in organic reactions: wool, silk, and feather. Moreover, we decided to focus on the other most important supports and catalysts in green syntheses, such as proteins and their derivates. Different materials have shown prominent activity in the adsorption of metals and organic dyes, which has constituted a relevant scope in the last two decades. We intend to furnish a complete screening of the application given to these materials and contribute to their potential future utilization.

Degradation of textile dyes from aqueous solution using tea-polyphenol/Fe loaded waste silk fabrics as Fenton-like catalysts

In this study, waste silk fabrics (SF) were modified with tea-polyphenols (TPs) and then iron (Fe²⁺). The modified silk fabrics (TP-SF/Fe) were characterized via Fourier-transform infrared (FTIR), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analysis. TP-SF/Fe was used in the Fenton-like removal of dyes (methylene blue, reactive orange GRN, and cationic violet X-5BLN) from aqueous solutions with catalyst-like activity. The effects of different catalyst samples, contact time, H₂O₂ concentration, initial dye concentration, and pH values on dye removal were investigated. The results showed that the dye removal percentages with the TP-SF/Fe-H₂O₂ sample reached 98%, 97%, and 95% in 5–40 min for methylene blue, reactive orange GRN, and cationic violet X-5BLN, respectively. Different thermodynamic and kinetic models were used to check the best fit of the adsorption data. The results indicated that the Freundlich isotherm and pseudo first-order kinetics models were the best fits. Moreover, it was also proved that TP-SF/Fe would be quite an effective and economical adsorbent for the treatment of textile dye wastewater. This work provides the basis for waste silk application in the removal of dyes from wastewater.

In this study, waste silk fabrics were modified with tea-polyphenols then loaded with Fe²⁺ for degradation of dyes.

Modification of fibrous membrane for organic and pathogenic contaminants removal: from design to application

In this study, a flexible multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane. Full characterization of the resulting polyester membranes allowed validation of successful grafting of amine/thiol (NH₂ or SH) functional groups and immobilization of Fe-NPs (50–150 nm). The Fenton-like functionality of iron immobilized fibrous membranes (PET–Fe, PET–Si–NH₂–Fe, PET–NH₂–Fe, and PET–SH–Fe) in the presence of hydrogen peroxide (H₂O₂) was comparatively studied in the removal of crystal violet dye (50 mg L⁻¹). The effect of pH, amount of iron and H₂O₂ concentration on dye removal was systematically investigated. The highest dye removal yield reached 98.87% in 22 min at a rate constant 0.1919 min⁻¹ (R² = 95.36) for PET–SH–Fe providing 78% toxicity reduction assessed by COD analysis. These membranes could be reused for up to seven repeated cycles. Kinetics and postulated mechanism of colour removal were proposed by examining the above results. In addition, the resultant membranes showed substantial antibacterial activity against pathogenic bacteria (Staphylococcus epidermidis, Escherichia coli) strains studied through disc diffusion-zone inhibitory and optical density analysis. These findings are of great importance because they provide a prospect of textile-based flexible catalysts in heterogeneous Fenton-like systems for environmental and green chemistry applications.

Multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane.