Microwave assisted rapid synthesis of Fe2O3@SiO2 core-shell nanocomposite for the persistence of magnetic property at high temperature

Design of Silica Nanoparticles-Supported Metal Catalyst by Wet Impregnation with Catalytic Performance for Tuning Carbon Nanotubes Growth

The catalytic activity of cobalt and iron nanoparticles for the growth of carbon nanotubes (CNTs) was studied by a specific reproducible and up-scalable fabrication method. Co and Fe catalysts were deposited over SiO2 nanoparticles by a wet-impregnation method and two different annealing steps were applied for the catalyst formation/activation. The samples were calcined at an optimal temperature of 450 °C resulting in the formation of metal oxide nano-islands without the detection of silicates. Further reduction treatment (700 °C) under H2 successfully converted oxide nanoparticles to Co and Fe metallic species. Furthermore, the catalytic efficiency of both supported-metal nanoparticles at 2 and 5% in weight of silica was evaluated through the growth of CNTs. The CNT structure, morphology and size dispersion were tailored according to the metal catalyst concentration.

Multiple Roles of Mesoporous Silica in Safe Pesticide Application by Nanotechnology: A Review

Pollution related to pesticides has become a global problem due to their low utilization and non-targeting application, and nanotechnology has shown great potential in promoting sustainable agriculture. Nowadays, mesoporous silica-based nanomaterials have garnered immense attention for improving the efficacy and safety of pesticides due to their distinctive advantages of low toxicity, high thermal and chemical stability, and particularly size tunability and versatile functionality. Based on the introduction of the structure and synthesis of different types of mesoporous silica nanoparticles (MSNs), the multiple roles of mesoporous silica in safe pesticide application using nanotechnology are discussed in this Review: (i) as nanocarrier for sustained/controlled delivery of pesticides, (ii) as adsorbent for enrichment or removal of pesticides in aqueous media, (iii) as support of catalysts for degradation of pesticide contaminants, and (iv) as support of sensors for detection of pesticides. Several scientific issues, strategies, and mechanisms regarding the application of MSNs in the pesticide field are presented, with their future directions discussed in terms of their environmental risk assessment, in-depth mechanism exploration, and cost-benefit consideration for their continuous development. This Review will provide critical information to related researchers and may open up their minds to develop new advances in pesticide application.

Smart Modification of HZSM-5 with Manganese Species for the Removal of Mercury

In this study, a series of Mn-modified HZSM-5 samples were synthesized using the solid-state ion-exchange method, and the effects of the manganese loading amount, calcination temperature, reaction temperature, and gas components on mercury removal efficiency were systematically explored. Given that the mass ratio of HZSM-5 to KMnO₄ and the calcination and reaction temperatures were set to 10:2.6 and 400 and 150 °C, Hg⁰ removal efficiency could reach a peak value of 96.4% when exposed to the flue gas containing 5% O₂ and N₂ as the balance. Among the various gas components, O₂ and NO showed a positive impact on Hg⁰ removal; Hg⁰ removal efficiency could even reach ca. 100% when O₂ and NO were simultaneously introduced. In contrast, the introduction of SO₂ led to a decline of Hg⁰ removal efficiency by ca. 16%. In addition, Hg⁰ removal efficiency could still retain ca. 92% of that for the fresh sample after six regeneration and reuse cycles, which is indicative of a satisfactory stability and renewability. Finally, Mars-Maessen mechanisms dominated in the mercury chemical adsorption process.

Core-Double-Shell Fe2O3@SiO2@Jarosite Hybrid Nanoparticles Synthesized by Laser Ablation of Turquoise in Ethanol

This work highlights a facile green route for the one-step synthesis of iron oxide core-double-shell nanoparticles (NPs) and aluminum phosphide (AlP) nanosheets by pulsed laser ablation of the mineral turquoise target from Nishapur in the presence of an ethanol solvent. High-resolution transmission electron microscopy, selected-area electron diffraction pattern, and field emission scanning electron microscopy (FESEM) in combination with energy-dispersive X-ray mapping revealed the formation of NPs with a typical core@double-shell structure in which crystalline α-Fe₂O₃ (iron oxide) formed the core, while SiO₂ (quartz) and (K, H₃O)Fe₃(SO₄)₂(OH₆) (jarosite) participated as the inner and outer shell, respectively. However, the application of laser ablation on the turquoise phase of the target led to the formation of AlP nanosheets which was confirmed by the X-ray diffraction patterns and FESEM images. Strong absorption of the vein-ablated species in the UV region (250-360 nm) was the characteristic feature of α-Fe₂O₃ and jarosite phases, while the absorption band at 250-300 nm for the turquoise-ablated species was related to the presence of Cu compound species and also the α-Fe₂O₃ phase in the sample. Photoluminescence emission spectra for the vein-ablated species depicted a peak centered at 370 nm, while a peak located at 364 nm was ascribed to the turquoise-ablated species. In particular, these hybrid NPs with high purity and stability may offer new opportunities for bio-applications such as anticancer agents and water/wastewater applications.