Catalytic Reduction of p-Nitrophenol and Hexacyanoferrate (III) by Borohydride Using Green Synthesized Gold Nanoparticles

Emerging micropollutants in aquatic ecosystems and nanotechnology-based removal alternatives: A review

There is a significant concern about the accessibility of uncontaminated and safe drinking water, a fundamental necessity for human beings. This concern is attributed to the toxic micropollutants from several emission sources, including industrial toxins, agricultural runoff, wastewater discharges, sewer overflows, landfills, algal blooms and microbiota. Emerging micropollutants (EMs) encompass a broad spectrum of compounds, including pharmaceutically active chemicals, personal care products, pesticides, industrial chemicals, steroid hormones, toxic nanomaterials, microplastics, heavy metals, and microorganisms. The pervasive and enduring nature of EMs has resulted in a detrimental impact on global urban water systems. Of late, these contaminants are receiving more attention due to their inherent potential to generate environmental toxicity and adverse health effects on humans and aquatic life. Although little progress has been made in discovering removal methodologies for EMs, a basic categorization procedure is required to identify and restrict the EMs to tackle the problem of these emerging contaminants. The present review paper provides a crude classification of EMs and their associated negative impact on aquatic life. Furthermore, it delves into various nanotechnology-based approaches as effective solutions to address the challenge of removing EMs from water, thereby ensuring potable drinking water. To conclude, this review paper addresses the challenges associated with the commercialization of nanomaterial, such as toxicity, high cost, inadequate government policies, and incompatibility with the present water purification system and recommends crucial directions for further research that should be pursued.

Simple Preparation of Porous Carbon-Supported Ruthenium: Propitious Catalytic Activity in the Reduction of Ferrocyanate(III) and a Cationic Dye

The present study involves the synthesis, characterization, and catalytic application of ruthenium nanoparticles (Ru NPs) supported on plastic-derived carbons (PDCs) synthesized from plastic wastes (soft drink bottles) as an alternative carbon source. PDCs have been further activated with CO₂ and characterized by various analytical techniques. The catalytic activity of Ru@PDC for the reduction of potassium hexacyanoferrate(III), (K₃[Fe(CN)₆]), and new fuchsin (NF) dye by NaBH₄ was performed under mild conditions. The PDCs had spherical morphology with an average size of 0.5 μm, and the Ru NP (5 ± 0.2 nm) loading (4.01 wt %) into the PDC provided high catalytic performance for catalytic reduction of ferrocyanate(III) and NF dye. This catalyst can be recycled more than six times with only a minor loss of its catalytic activity. In addition, the stability and reusability of the Ru@PDC catalyst are also discussed.

Ultrasonic assisted synthesis of palladium-nickel/iron oxide core-shell nanoalloys as effective catalyst for Suzuki-Miyaura and p-nitrophenol reduction reactions

In this study, ultrasonic assisted synthesis of Pd-Ni/Fe₃O₄ core-shell nanoalloys is reported. Unique reaction condition was prepared by ultrasonic irradiation, releasing the stored energy in the collapsed bubbles and heats the bubble contents that leads to Pd(II) and Ni(II) reduction. Co-precipitation method was applied for the synthesis of Fe₃O₄ nanoparticles (NPs). Immobilized solution was produced by sonicating the aqueous mixture of Fe₃O₄ and mercaptosuccinic acid to obtain Pd-Ni alloys on Fe₃O₄ magnetic NP cores. The catalytic activity of the synthesized Pd-Ni/Fe₃O₄ core-shells was investigated in the Suzuki-Miyaura CC coupling reaction and 4-nitrophenol reduction, which exhibited a high catalytic activity in both reactions. These magnetic NPs can be separated from the reaction mixture by external magnetic field. This strategy is simple, economical and promising for industrial applications.

PdNP Decoration of Halloysite Lumen via Selective Grafting of Ionic Liquid onto the Aluminol Surfaces and Catalytic Application

The synthesis of selectively deposited palladium nanoparticles (PdNPs) inside tubular halloysite lumens is reported. This specific localization was directed by the selective modification of the aluminol surfaces of the clay mineral through stable Al-O-C bonds. An ionic liquid (1-(2-hydroxyethyl)-3-methylimidazolium) was grafted onto halloysite following the guest displacement method (generally used for kaolinite) using halloysite-DMSO preintercalate. The characterization of this clay nanohybrid material (XRD, NMR, TGA) showed characteristics reminiscent of similar materials synthesized from kaolinite. The grafting on halloysite lumens was also effective without using the DMSO preintercalate. The presence of these new functionalities in halloysite directs the synthesis of uniform PdNPs with size ranging between 3 and 6 nm located exclusively in the lumens. This results from the selective adsorption of PdNPs precursors in functionalized lumens through an anion exchange mechanism followed by in situ reduction. In contrast, the unmodified clay mineral displayed nanoparticles both inside and outside the tubes. These catalysts showed significant catalytic activity for the reduction of 4-nitrophenol (4-NP). The most efficient catalysts were recycled up to three times without reducing significantly the catalytic activities.