Powders

In recent years, sustainable recycling approaches for chicken eggshell waste have increased significantly worldwide due to environmental and circular economy benefits. This work aimed to synthesize and characterize a new calcium aluminate powder using chicken eggshell waste as an alternative source of calcium carbonate through mechanical activation and subsequent calcination. The starting formulation consisting of the eggshell waste (CaCO₃):Al₂O₃ (1:1) ratio was subjected to a high-energy milling process for 0 h, 15 h and 30 h and subsequent calcination at 1200 °C for 4 h. The resulting calcium aluminate powders have been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and photoluminescence techniques. After calcination, a calcium aluminate-based composite powder with an average crystallite size between 46.45 nm and 52.27 nm and a predominance of the CaAl₂O₄ phase was found. The calcium aluminate powders produced (milled for 15 h and 30 h and calcined at 1200 °C) showed a luminescent behavior, emitting characteristic violet light with a wavelength between 380 and 418 nm. Our findings may provide a novel technical pathway for recycling chicken eggshell waste into calcium aluminate powder with luminescent properties.

Environmental contamination is a significant challenge, and nanotechnology shows promise in restoring ecosystems impacted by human activity. Magnetic zinc oxide nanoparticles (ZnO-NPs) are notable for their antimicrobial and photocatalytic properties, making them valuable for various environmental and medical applications. Their ability to be recovered and reused in the presence of a magnetic field enhances process sustainability. Furthermore, green synthesis using low-toxicity biological agents such as plant extracts and microorganisms offers a safer and more eco-friendly alternative to traditional methods. This systematic review examines the green synthesis of magnetic ZnO nanocomposites, highlighting advanced production techniques, methods, and potential applications. Four of the eleven studies analyzed specifically address the photocatalytic activity of green-synthesized ZnO nanocomposites, emphasizing their promise in environmental domains.

Particles travelling within and interacting with any fluid media are found in both natural phenomena and industrial processes. Through these interactions, the particles experience a drag force, heavily influenced by their morphology, and significantly affecting their dynamics. This study examines the relationship between particle morphology and the drag force exerted on them, using both empirical models and computational simulations. The findings indicate that for regular and irregular particles of diverse morphologies, a combination of existing empirical models can predict the drag force within a 40% error margin. However, these models may fall short of meeting the accuracy demands in certain applications. To address this, the study provides clear guidelines for selecting the most suitable drag model based on particle morphology and flow regime.