Microwave-Assisted Catalytic Deconstruction of Plastics Waste into Nanostructured Carbon and Hydrogen Fuel Using Composite Magnetic Ferrite Catalysts.

Finding new catalysts and pyrolysis technologies for efficiently recycling wasted plastics into fuels and structured solid materials of high selectivity is the need of time. Catalytic pyrolysis is a thermochemical process that cracks the feedstock in an inert gas environment into gaseous and liquid fuels and a residue. This study is conducted on microwave-assisted catalytic recycling of wasted plastics into nanostructured carbon and hydrogen fuel using composite magnetic ferrite catalysts. The composite ferrite catalysts, namely, NiZnFe2O4, NiMgFe2O4, and MgZnFe2O4 were produced through the coprecipitation method and characterized for onward use in the microwave-assisted valorization of wasted plastics. The ferrite nanoparticles worked as a catalyst and heat susceptor for uniformly distributed energy transfer from microwaves to the feedstock at a moderate temperature of 450°C. The type of catalyst and the working parameters significantly impacted the process efficiency, gas yield, and structural properties of the carbonaceous residue. The tested process took 2-8 minutes to pulverize feedstock into gas and carbon nanotubes (CNTs), depending on the catalyst type. The NiZnFe2O4-catalyzed process produced CNTs with good structural properties and fewer impurities compared to other catalysts. The NiMgFe2O4 catalyst performed better in terms of hydrogen evolution by showing 87.5% hydrogen (H2) composition in the evolved gases. Almost 90% of extractable hydrogen from the feedstock evolved during the first 2 minutes of the reaction.

Study of Cation Distribution and Photocatalytic Activity of Nonthermal Plasma-Modified NiZnFe2O4 Magnetic Nanocomposites.

In this study, NiZnFe2O4 composite was synthesized using a sol-gel route and subjected to nonthermal plasma treatment for tailoring their cations' distribution and physicochemical, magnetic, and photocatalytic properties. Microwave plasma treatment was given to the composites for 60 min in support of postsynthesis sintering at 700 °C for 5 h. X-ray diffraction (XRD) analysis was conducted on pre- and postplasma-modified ferrite composites to identify phase-pure cubic spinel structure and cations' distribution. The cation distributions were measured from the ratio of XRD intensity peaks corresponding to (220), (311), (422) and (440) planes. The intensity ratio of plasma-treated ferrite composites decreased compared to that of pristine composites. The crystallite size and lattice constant were increased on plasma treatment of the composite. The morphological analysis showed nanoflower-like structures of the particles with an increased surface area in the plasma-treated composites. The plasma oxidation and sputtering effects caused a reduction in the nanoflower size. The energy bandgap increased with a decrease in particle size due to plasma treatment. The rhodamine B dye solution was then irradiated with a light source in the presence of the nanocomposites. The dye degradation efficiency of the composite photocatalyst increased from 80 to 96% after plasma treatment.