Antioxidative, Hemocompatible, Fluorescent Carbon Nanodots from an “End-of-Pipe” Agricultural Waste: Exploring Its New Horizon in the Food-Packaging Domain

The attention of researchers is burgeoning toward oilseed press-cake valorization for its high protein content. Protein removal from oil-cakes generates large quantities of fibrous residue (oil-and-protein spent meal) as a byproduct, which currently has very limited practical utility. In the wake of increasing awareness in waste recycling, a simple environmentally benign hydrothermal carbonization process to convert this “end-of-pipe” waste (spent meal) into antioxidative, hemocompatible, fluorescent carbonaceous nanoparticles (FCDs) has been described. In the present investigation, an interesting application of FCDs in fabricating low-cost rapeseed protein-based fluorescent film, with improved antioxidant potential (17.5–19.3-fold) and thermal stability has been demonstrated. The nanocomposite film could also be used as forgery-proof packaging due to its photoluminescence property. For assessing the feasibility of antioxidative FCDs in real food systems, a comparative investigation was further undertaken to examine the effect of such nanocarbon-loaded composite film on the oxidative shelf life of rapeseed oil. Oil samples packed in nanocomposite film sachets showed significant delay in oxidative rancidity compared to those packed in pristine protein-film sachet (free fatty acids, peroxide value, and thiobarbituric acid-reactive substances reduced up to 1.4-, 2-, and 1.2-fold, respectively). The work presents a new concept of biobased fluorescent packaging and avenues for harnessing this potent waste

Graphene Derivative in Magnetically Recoverable Catalyst Determines Catalytic Properties in Transfer Hydrogenation of Nitroarenes to Anilines with 2‑Propanol

Here, we report transfer hydrogenation of nitroarenes to aminoarenes using 2-propanol as a hydrogen source and Ag-containing magnetically recoverable catalysts based on partially reduced graphene oxide (pRGO) sheets. X-ray diffraction and X-ray photoelectron spectroscopy data demonstrated that, during the one-pot catalyst synthesis, formation of magnetite nanoparticles (NPs) is accompanied by the reduction of graphene oxide (GO) to pRGO. The formation of Ag⁰ NPs on top of magnetite nanoparticles does not change the pRGO structure. At the same time, the catalyst structure is further modified during the transfer hydrogenation, leading to a noticeable increase of sp² carbons. These carbons are responsible for the adsorption of substrate and intermediates, facilitating a hydrogen transfer from Ag NPs and creating synergy between the components of the catalyst. The nitroarenes with electron withdrawing and electron donating substituents allow for excellent yields of aniline derivatives with high regio and chemoselectivity, indicating that the reaction is not disfavored by these functionalities. The versatility of the catalyst synthetic protocol was demonstrated by a synthesis of an Ru-containing graphene derivative based catalyst, also allowing for efficient transfer hydrogenation. Easy magnetic separation and stable catalyst performance in the transfer hydrogenation make this catalyst promising for future applications

Oriented Attachment Is a Major Control Mechanism To Form Nail-like Mn-Doped ZnO Nanocrystals

Here, we present a controlled synthesis of Mn-doped ZnO nanoparticles (NPs) with predominantly nail-like shapes, whose formation occurs via tip-to-base-oriented attachment of initially formed nanopyramids, followed by leveling of sharp edges that lead to smooth single-crystalline “nails”. This shape is prevalent in noncoordinating solvents such as octadecene and octadecane. Yet, the double bond in the former promotes oriented attachment. By contrast, Mn-doped ZnO NP synthesis in a weakly coordinating solvent, benzyl ether, results in dendritic structures because of random attachment of initial NPs. Mn-doped ZnO NPs possess a hexagonal wurtzite structure, and in the majority of cases, the NP surface is enriched with Mn, indicating a migration of Mn²⁺ ions to the NP surface during the NP formation. When the NP formation is carried out without the addition of octadecyl alcohol, which serves as a surfactant and a reaction initiator, large, concave pyramid dimers are formed whose attachment takes place via basal planes. UV–vis and photoluminescence spectra of these NPs confirm the utility of controlling the NP shape to tune electro-optical properties