This study presents an integrated approach for the sustainable management of healthcare waste (HCW) through slow pyrolysis and the application of the resulting pyrolytic char (Pc) for electrochemical sensing of estriol (E3), an emerging contaminant, in environmental and pharmaceutical samples. Pc was produced by the pyrolysis of HCW at 400 °C and characterized by Brunauer–Emmett–Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Pc exhibited a mesoporous structure with a specific surface area of 6.9 m² g⁻¹, a pore volume of 0.026 cm³ g⁻¹, and an average pore diameter of 14.44 nm. Morphological analysis revealed a heterogeneous surface with a composition dominated by carbon (61.3
The present work deals with an investigation, on novel ultrasensitive nitrite ion detection by a nanocomposite film of ZnO honeycomb nanosheets Modified Glassy Carbon Electrode (Ns-ZnO-GCE). The Ns-ZnO-GCE was prepared from ZnO nanosheets that were hydrothermally prepared and physically adsorbed on the carbon electrode. The obtained material shows a bright white visual color, which is indicative of the ZnO compound. Morphologies of the nanocomposite were characterized via UV-Vis spectroscopy, FE-SEM, TEM, and XRD. Then the electrochemical behavior of the nanocomposite, under neutral conditions, was studied using nitrite as a model. It is worth noting that these nanosheets show outstanding efficacy and fascinating sensor properties. The research focuses on the ZnO material and also proposes a potential reaction mechanism for the conversion of nitrite to nitrate. As a consequence, nitrite was detected sensitively at the modified electrode within the linear range of 10 µM to 100 µM. The proposed method could be used properly for nitrite detection in tap water samples with satisfactory performance. This outcome suggests the feasibility of Ns-ZnO-GCE as an alternative electrode platform for nitrite ion detection. On the other hand, ZnO honeycomb nanocatalyst can be applied for catalytic purposes such as the synthesis of 2-benzylidene malononitrile and the procedure is compared favorably with other nanocatalytic systems reported earlier, regarding time, yield, and sustainability, thereby supporting its usefulness as a green and scalable synthetic approach.
After a short introduction about the concept of model catalysis, there will be three subjects covered within this review and perspective, based mainly on our own research. The first one deals with atomic defects in thin oxide films, which are used to model the catalyst support, and their charge state as a function of film thickness. In a second section we review the properties of single metal atoms and metal clusters, where we concentrate on Au, which has been identified in the late 1980ies as a possible catalytic species. We show, how the shape of the clusters depends on the detailed structure of the oxide films, and how we can use the electronic structure, as observed by STM, to determine the number of atoms constituting the particle, even though the atomic structure cannot be resolved directly by topographic STM. In the third part we introduce a novel technique for vibrational structure determination. We call this technique surface action spectroscopy, which is based on a technique, called action spectroscopy, used to determine cluster structures in the gas phase. We show an example how the technique can be used in surface science to determine the structure of an oxide film support, and we suggest a way of how it could be used to study the structure of deposited clusters.
The complexes of Nickel(II) and manganese(II) containing of 2(2′-quinolyl)-benzimidazole have been anchored onto a copolymer of styrene and divinyl benzene. The unsupported and immobilized complexes were characterized by diverse analytical techniques. The present polymer supported complexes attributed significant catalytic activity for the liquid-liquid phase oxidation of benzoin in methanol under ambient conditions and, revealed the selectivity to benzil. The Possible reaction mechanism has also been worked out. Further, the heterogeneity tests and recyclability investigation of the catalysts evidenced the immobilization of the catalyst on the polymer support and good salvaging ability without substantial leaching of the metals despite five cycles.
Multicomponent reactions (MCRs) have attracted considerable attention in the field of sustainable and green chemistry because of their excellent atom economy, versatility, and reproducibility. These reactions provide an efficient route for synthesizing novel organic compounds, as they minimize the need for multiple purification steps and allow the formation of the final product in a single one-pot process. One of the key challenges in MCRs is carrying out these reactions in an environmentally friendly manner, where the choice of solvent plays a crucial role. Water is often considered an ideal green solvent, as it can enhance both the selectivity and reactivity of chemical transformations, although it may pose limitations due to the poor solubility of many organic substrates. To overcome this issue, surfactants are commonly used to improve substrate solubility. Surfactants, which form micellar structures in solution, not only improve reaction rates and yields but also reduce the interfacial tension between organic and aqueous phases. Their role can be understood in two ways: first, they encapsulate the reactants within micelles, effectively bringing them closer together and facilitating interaction; second, the hydrophobic products tend to associate with the micellar core, which helps shift the reaction equilibrium toward product formation.
