Magnetic boron nitride adorned with Pd nanoparticles: an efficient catalyst for the reduction of nitroarenes in aqueous media

Magnetic nickel nanoparticle catalyst on β-cyclodextrin-modified Fe3O4 for nitroarene hydrogenation

This study developed a novel and highly active heterogeneous catalyst of nickel nanoparticles supported on β-cyclodextrin-grafted magnetic Fe3O4 nanoparticles (Ni@β-CD@Fe3O4). β-CD, a biodegradable, biocompatible, green, and non-toxic cyclic oligosaccharide, was modified with Fe3O4 nanoparticles to create β-CD@Fe3O4. The nickel was then immobilized onto this support. The catalyst was characterized using FT-IR, XRD, TEM, AAS, FE-SEM, TGA, EDX, DRS-UV-Vis spectra, and VSM techniques. The catalytic activity of Ni@β-CD@Fe3O4 was evaluated for the reduction of nitroarene compounds in water at 25 ℃. This nanocatalyst indicated great activity and selectivity in reducing various nitroarenes, including nitrobenzene, nitroaniline, nitrotoluene, and nitrophenol derivatives. Additionally, the catalyst showed significant reusability and could be easily separated using an external magnet, highlighting its potential for green chemistry and sustainable industrial applications.

Nitrate and nitroarene hydrogenations catalyzed by alkaline-earth nickel phosphide clathrates

The alkaline-earth-containing nickel phosphide clathrates AeNi2P4 (Ae = Ba, Sr) are investigated as catalysts for the reduction of nitrate or nitroarenes in aqueous or ethanolic solution, respectively. While AeNi2P4 clathrates are inactive in their bulk polycrystalline form, they become active in nitrate hydrogenation after size reduction by either grinding or ball milling. However, while the clathrate structure remains intact after manual grinding, ball milling is of limited use as it results in significant clathrate degradation. Ground AeNi2P4 catalysts are also active in nitroarene hydrogenation. Condensation products such as azoxy- and azo-benzenes form early (4 h) but anilines accumulate after long reaction times (24 h). Unexpectedly, BaNi2P4 partially devinylates nitrostyrene to nitrobenzene. Overall, BaNi2P4 is more active than SrNi2P4 in both nitrate and nitroarene hydrogenation. These results showcase the potential utility of clathrates in a growing number of catalytic transformations.

Recent advances in the application of magnetic nanocatalysts in multicomponent reactions

Recently, the preparation and applications of magnetic nanostructures have attracted increasing attention in nanocatalysis studies, and magnetic nanoparticle (MNP) functionalized catalysts have been applied in important reactions such as Suzuki-Miyaura and Heck couplings. The modified nanocomposites demonstrate significant catalytic efficiency and excellent benefits in the context of catalyst recovery methods. This review discusses the recent modified magnetic nanocomposites in the field of catalytic applications along with the synthetic processes that are usually employed.

Progresses in lignin, cellulose, starch, chitosan, chitin, alginate, and gum/carbon nanotube (nano)composites for environmental applications: A review

Water sources are becoming increasingly scarce, and they are contaminated by industrial, residential, and agricultural waste-derived organic and inorganic contaminants. These contaminants may pollute the air, water, and soil in addition to invading the ecosystem. Because carbon nanotubes (CNTs) can undergo surface modification, they can combine with other substances to create nanocomposites (NCs), including biopolymers, metal nanoparticles, proteins, and metal oxides. Furthermore, biopolymers are significant classes of organic materials that are widely used for various applications. They have drawn attention due to their benefits such as environmental friendliness, availability, biocompatibility, safety, etc. As a result, the synthesis of a composite made of CNT and biopolymers can be very effective for a variety of applications, especially those involving the environment. In this review, we reported environmental applications (including removal of dyes, nitro compounds, hazardous materialsو toxic ions, etc.) of composites made of CNT and biopolymers such as lignin, cellulose, starch, chitosan, chitin, alginate, and gum. Also, the effect of different factors such as the medium pH, the pollutant concentration, temperature, and contact time on the adsorption capacity (AC) and the catalytic activity of the composite in the reduction or degradation of various pollutants has been systematically explained.