Transformation of Waste Toner Powder into Valuable Fe₂O₃ Nanoparticles for the Preparation of Recyclable Co(II)-NH₂-SiO₂@Fe₂O₃ and Its Applications in the Synthesis of Polyhydroquinoline and Quinazoline Derivatives

Abstract

Ecological recycling of waste materials by converting them into valuable nanomaterials can be considered a great opportunity for management and fortification of the environment. This article deals with the environment-friendly synthesis of Fe2O3 nanoparticles (composed of α-Fe2O3 and γ-Fe2O3) using waste toner powder (WTP) via calcination. Fe2O3 nanoparticles were then coated with silica using TEOS, functionalized with silane (APTMS), and immobilized with Co­(II) to get the desired biocompatible and cost-effective catalyst, i.e., Co­(II)-NH2-SiO2@Fe2O3. The structural features in terms of evaluation of morphology, particle size, presence of functional groups, polycrystallinity, and metal content over the surface were determined by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (P-XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy-dispersive X-ray analysis (EDX), high resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller (BET) analysis, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) studies. XPS confirmed the (II) oxidation state of Co, and ICP-AES and EDX supported the loading of Co­(II) over the surface of the support. P-XRD proved the polycrystalline nature of the Fe2O3 core and even after functionalization. In comparison to previously reported methods, Co­(II)-NH2-SiO2@Fe2O3 provides an eco-friendly procedure for the synthesis of polyhydroquinoline and quinazoline derivatives with several advantages such as a short reaction time and high yield. Polyhydroquinoline and quinazoline derivatives are important scaffolds in pharmacologically active compounds. Moreover, the developed nanocatalyst was recyclable, and HR-TEM and P-XRD confirmed the agglomeration in the recycled catalyst resulted in a decrease in yield after the fifth run. The present protocol provides a new strategy of recycling e-waste into a heterogeneous nanocatalyst for the synthesis of heterocycles via multicomponent reactions. This made the synthesized catalyst convincingly more superior to other previously reported catalysts for organic transformations.

Extraction of gamma iron oxide (γ-Fe2O3) nanoparticles from waste can: Structure, morphology and magnetic properties

“… Precursor Synthesis procedure Final Product Crystallite size (nm) Ms (emu/g) Hc (Oe) Application Ref. Scrap iron Hydrothermal γ-Fe 2 O 3 nanoparticles 20 to 40 0.3813 10 Environmental waste management [ 1 ] Iron pentacarbonyl, Fe(CO) 5 Microwave plasma synthesis γ-Fe 2 O 3 nanoparticles 2 to ∼50 13.2–67.6 – Impact of size reduction [ 7 ] Slag, mill scale, scrap and iron dust Co-precipitation γ-Fe 2 O 3 particles 11.04 to 18.62 17.44–41.69 3.464–60.193 Waste disposal problem [ 42 ] Waste Toner Powder Thermal transformation technique Magnetic iron oxide nanoparticles 32.07 19.5 – Preparation of Recyclable Co(II)– NH 2 –SiO 2 @Fe 2 O 3 [ 69 ] Iron chloride and urea Co-precipitation γ-Fe 2 O 3 nanoparticles 60 0.025 1250 Removal of toxic heavy metals from electroplating wastewater [ 70 ] Recyclable electro-coagulated sludge …”

Synthesis of Nitrogen- and Oxygen-Containing Heterocycles Catalysed by Metal Nanoparticles Reported in 2022

“…Beller et al focussed on synthesising novel heterogeneous NiNPs and demonstrated their catalytic and effective use as catalysts for the hydrogenation of quinolines (101), isoquinolines (103), indole (105), and 1,10-phenanthroline (107) to give the corresponding tetrahydro derivatives (102/104/106/108; Scheme 30). 83 These NiNPs were synthesised from silica, nickel acetate and 1,10-phenanthroline followed by pyrolysis at 800 °C under argon medium.…”

“…Gupta et al synthesised polyhydroquinolones using Co(II)-NH 2 -SiO 2 @Fe 2 O 3 NPs as the catalyst (Scheme 48). 101 The authors attempted the transformation of waste toner powder into recyclable NPs and analysed their applications for the synthesis of these heterocycles. Fe 2 O 3 NPs were formed via calcination, functionalised with silane and coated with silica followed by their immobilisation using Co(II) salts.…”

Tunning of catalytic performance in coupling, reduction and oxidation of hydrothermal assisted mixed metal oxides of Pd and Cu loaded over mesoporous nanostructure titania coated N‐doped silica using rice husk

“…Nanocatalysis acts as bridge between homogeneous and heterogeneous catalyst. 4 Both homogeneous and heterogeneous catalysts are combined when catalytic support is added to nanocatalyst. In Chemistry, a catalyst support is a material, usually a solid with a high surface area, to which a catalyst is affixed.…”

“…Nanocatalysis opens up a number of opportunities in sustainable and Green chemistry because it lessens the amount of waste, usage of potentially harmful chemicals and energy consumption connected with a chemical process. Nanocatalysis acts as bridge between homogeneous and heterogeneous catalyst 4 . Both homogeneous and heterogeneous catalysts are combined when catalytic support is added to nanocatalyst.…”