Eggshell Membrane-Supported Recyclable Catalytic Noble Metal Nanoparticles for Organic Reactions

Heterogeneous catalysts are used in many industrial processes. Here, we report a simple method for a template-assisted synthesis of nanoparticle catalysts and for testing their catalytic efficiency toward two model organic reactions. Eggshell membrane (ESM) reduced metal cations to metal atoms, stabilized the nanoparticles, and was used as a supporting material for the nanoparticles. The gold and silver nanoparticles were characterized using UV–vis spectroscopy, FESEM, XRD, and XPS studies. As a proof of concept, the resultant membrane-supported nanoparticles were used as a heterogeneous catalyst for the reduction of p-nitrophenol and synthesis of propargylamine. High recyclability of the reactions indicates that nanoparticles are strongly attached to the eggshell membrane surface. Easy synthesis, high catalytic activity, and recyclability make these catalysts interesting for further studies

Functionalized Carbon Spheres for Extraction of Nanoparticles and Catalyst Support in Water

Increased use of nanomaterials in commercial products will lead to environmental contamination in the near future. So far, limited adsorbents are available for the removal of such emerging pollutants from water. The objective of this work was to synthesize functionalized carbon nanospheres (C-spheres) for the removal of emerging nanopollutants from water and to study the mechanisms involved. C-spheres were prepared using hydrothermal carbonization of glucose. Post-modification with polyethylenimine (PEI) generated amine-coated C-spheres, followed by protonation using diluted acid solution. The surface functional groups and morphologies of the C-spheres were characterized using infrared spectroscopy and field emission scanning electron microscopy, respectively. The C-spheres were used for the extraction of citrate-capped gold and silver nanoparticles from water. The equilibrium adsorption data was interpreted using Langmuir and Freundlich isotherms, and the adsorption mechanism was investigated using kinetic studies. Our data suggest that the adsorption of nanoparticles on modified C-spheres followed pseudo-second-order kinetics, and adsorption can be best explained by the Langmuir adsorption model. The observed results suggest that the developed material shows enhanced extraction capacities (102 mg/g for AuNPs and 135 mg/g for AgNPs). Further, the NP-adsorbed C-spheres were evaluated for the catalytic reduction of p-nitrophenol to demonstrate the activity of adsorbed NPs

Functionalized Carbon Spheres for Extraction of Nanoparticles and Catalyst Support in Water

Increased use of nanomaterials in commercial products will lead to environmental contamination in the near future. So far, limited adsorbents are available for the removal of such emerging pollutants from water. The objective of this work was to synthesize functionalized carbon nanospheres (C-spheres) for the removal of emerging nanopollutants from water and to study the mechanisms involved. C-spheres were prepared using hydrothermal carbonization of glucose. Post-modification with polyethylenimine (PEI) generated amine-coated C-spheres, followed by protonation using diluted acid solution. The surface functional groups and morphologies of the C-spheres were characterized using infrared spectroscopy and field emission scanning electron microscopy, respectively. The C-spheres were used for the extraction of citrate-capped gold and silver nanoparticles from water. The equilibrium adsorption data was interpreted using Langmuir and Freundlich isotherms, and the adsorption mechanism was investigated using kinetic studies. Our data suggest that the adsorption of nanoparticles on modified C-spheres followed pseudo-second-order kinetics, and adsorption can be best explained by the Langmuir adsorption model. The observed results suggest that the developed material shows enhanced extraction capacities (102 mg/g for AuNPs and 135 mg/g for AgNPs). Further, the NP-adsorbed C-spheres were evaluated for the catalytic reduction of <i>p</i>-nitrophenol to demonstrate the activity of adsorbed NPs

Fruit Peels as Efficient Renewable Adsorbents for Removal of Dissolved Heavy Metals and Dyes from Water

Removal of heavy metal ions and dissolved organic compounds present in wastewater is a challenge for many countries owing to high cost of existing technologies and continued increase in water consumption. In this study, three natural materials, avocado, hamimelon and dragon fruit peels, were selected and used as simple and renewable adsorbents for water purification. The presence of surface functional groups such as −CO₂H, −OH and morphologies of the peels were characterized using spectroscopic and electron microscopic techniques, respectively. All peals were effective toward removing dyes and toxic metal ions from water. The extraction capacity of peels increased with extraction time and a plateau was reached at equilibrium. Dragon fruit peels showed highest extraction efficiency toward alcian blue (71.85 mg/g) and methylene blue (62.58 mg/g). Hamimelon peels and avaocado peels showed moderate extraction capacity for Pb²⁺ (7.89 mg/g, 9.82 mg/g) and Ni²⁺ (9.45 mg/g, 4.93 mg/g) cations. The Langmuir isotherm model was useful to explain the adsorption process, dominated by electrostatic interaction between adsorbent and adsorbates, indicating a monolayer adsorption at the binding sites on the surface of the peels. However, the adsorption model for methylene blue and neutral red is still a matter of conjecture. The adsorbents can be regenerated at acidic pH and could reuse for a few cycles

PVA/Gluten Hybrid Nanofibers for Removal of Nanoparticles from Water

Recent developments in nanotechnology led to the incorporation of many nanomaterials into consumer products. Disposal of such products will lead to potential contamination of the environment. Nanomaterials are emerging contaminants in water and show significant toxicity to living systems. Considering the diversity in structure and properties, removal of nanopollutants from water warrants novel methods and materials. The objective of this study was to prepare PVA/gluten hybrid nanofibers, which are nontoxic and biodegradable adsorbents for the extraction of nanopollutants from water. Surface morphology, elemental composition, and functional groups on the fiber surface were established using microscopic and spectroscopic techniques. Influence of analytical factors such as experimental pH, time, and concentration of the pollutants toward establishing the efficiency of extraction were quantified using UV–vis spectroscopy. Nanofiber mats with 5 wt % gluten exhibited high extraction efficiency of 99% toward citrate-capped silver (Ag) and gold (Au) nanoparticles with a maximum adsorptive capacity of 31.84 mg/g for Ag NPs and 36.54 mg/g for AuNPs. The kinetic and equilibrium adsorption data were interpreted using Freundlich and Langmuir isotherm models, and a potential adsorption mechanism was suggested. The adsorption kinetics showed a pseudo-second-order model for the extraction of nanoparticles. The prepared PVA/gluten hybrid nanofibers can be utilized as an efficient low-cost adsorbents for removal and recovery of metal nanoparticles from the aqueous environment