Synergistic Photocatalysis by α-MoO3 Nanostructures and SWCNT Nanocomposites for Efficient Cross-Linking and Oxidative Degradation of Polystyrene Nanoplastics.

Nanoplastics (NPs) generated from plastic debris weathering pose a significant threat to ecosystems. The ubiquity of plastics driven by their advantageous physical properties, necessitates the development of efficient degradation and removal methods. Polystyrene (PS), a common and hazardous aquatic NP is a long-chain hydrocarbon with alternating phenyl groups. This study investigates the photooxidative degradation of PS NPs under UV light irradiation using synthesized MoO3 nanoflakes, nanobelts, and MoO3/SWCNT nanocomposites. Raman spectroscopy, X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray, Brunauer-Emmett-Teller, and UV-vis spectroscopy were employed to characterize the photocatalyst. Field emission scanning electron microscopy was used to visualize morphological changes in the spherical PS NPs upon interaction with the photocatalysts. MoO3 nanoflakes acting as a photocatalyst under UV irradiation for 24 h achieved an impressive degradation efficiency exceeding 19%. This treatment significantly reduced the average diameter of PS NPs from 220 to 178 nm. Notably, even higher degradation efficiencies were observed with MoO3 nanobelts and nanocomposites as a complete change in the spherical morphology of PS NPs is observed. Fourier transform infrared spectroscopy elucidated the chemical transformations of PS during degradation. The observed changes in PS NPs structure due to photocatalytic oxidation at different time intervals indicate a promising approach.

In Situ Fabrication and Characterization of g-C3N4 onto Cellulose Nanofibers and Selective Separation of Heavy Metal Ions.

Graphitic carbon nitride nanosheets were synthesized onto cellulose nanofiber surfaces utilizing an eco-friendly salt melt approach. The fabricated material CNF@C3N4 selectively removes Ni(II) and Cu(II) from electroplating wastewater samples. The immobilization of g-C3N4 on solid substrates eases handling of nanomaterial in a flow-through approach and mitigates sorbent loss during column operations. Characterization techniques such as scanning electron microscopy, tunneling electron microscopy, and X-ray photoelectron microscopy were employed to analyze the surface morphology and chemical bonding within the synthesized material. Selective Cu(II) and Ni(II) sorption predominantly arises from the soft-soft interaction between metal ions and associated nitrogen groups. An inner-sphere surface complexation mechanism effectively elucidated the interaction dynamics between the metal and CNF@C3N4. Experimental findings demonstrated satisfactory separation of Ni(II) and Cu(II) ions, with the extraction of 340.0 and 385.0 mg g-1 of material, respectively. Additionally, the devised technique was executed for the preconcentration and quantification of trace metals ions in water samples with a detection limit and limit of quantification of 0.06 and 0.20 µg L-1, respectively.

Layered Double Hydroxides for Regulating Phosphate in Water to Achieve Long-Term Nutritional Management.

Hunger and undernourishment are increasing global challenges as the world's population continuously grows. Consequently, boosting productivity must be implemented to reach the global population's food demand and avoid deforestation. The current promising agricultural practice without herbicides and pesticides is fertilizer management, particularly that of phosphorus fertilizers. Layered double hydroxides (LDHs) have recently emerged as favorable materials in phosphate removal, with practical application possibilities in nanofertilizers. This review discusses the fundamental aspects of phosphate removal/recycling mechanisms and highlights the current endeavors on the development of phosphate-selective sorbents using LDH-based materials. Specific emphasis is provided on the progress in designing LDHs as the slow release of phosphate fertilizers reveals their relevance in making agro-practices more ecologically sound. Relevant pioneering efforts have been briefly reviewed, along with a discussion of perspectives on the potential of LDHs as green nanomaterials to improve food productivity with low eco-impacts.

Avenue to Large-Scale Production of Graphene Quantum Dots from High-Purity Graphene Sheets Using Laboratory-Grade Graphite Electrodes.

Graphene has unprecedented physical, chemical, and electronic properties, but need of the hour is to develop low-dimensional nanomaterials, such as graphene quantum dots (GQDs), that could be incorporated into nanoscale devices. This article depicts the production of GQDs from ultrafine, thin (0.8-1 nm), bilayer graphene sheets (GSs) possessing large micron-sized lateral dimension, low defect density (I D/I G: 0.1), and oxidation degree (C/O ratio: 27) of lowest level, in contrast to many other techniques where synthesis of GSs was done using analytical-grade expensive graphite electrodes. This low-cost manufacturing of GSs for industrial-scale applications was achieved by utilizing only 99%-purity graphite electrodes. The variants of such graphite electrodes (graphite rod, film, pencil) are etched in different pH electrolytes (H2SO4, NaCl, NaOH) via prompt electrochemical exfoliation, each giving more than 50% yield. Nowadays, semiconductor quantum dots (QDs) are utilized in smart device production industries, but their toxicity is a major issue of concern. Therefore, the dimension of this two-dimensional (2D) material is reduced to <10 nm to generate GQDs. A facile and highly reproducible approach has been reported for the large-scale generation of GQDs (size ca. 6-10 nm) with minimal surface defects. The protocol followed in this article to synthesize GQDs involves the use of ethylenediamine (en), which passivates the surface and reduces defects, thereby enhancing the optical properties. We demonstrate the correlation of the electrochemical and hydrothermal parameters with the growth mechanism and morphological, structural, chemical, and optical properties of the graphene nanomaterials. Raman spectroscopy and X-ray diffraction (XRD) reveal the structural configurations of GSs and GQDs to investigate the nature of defects. Field emission scanning electron microscopy (FESEM) confirms the morphological characteristics of the as-prepared GSs and GQDs with energy-dispersive X-ray (EDX) analysis determining the C/O ratio. The optical properties like UV-visible absorption and fluorescence assays show the quantum confinement effect phenomenon in GQDs. The obtained GSs and GQDs display enhanced solution stability in DI water and other solvents due to controllable oxidation degree as elucidated through Fourier transform infrared (FTIR) analysis.