Effective treatment of organic dye-contaminated water is of great importance, and graphene derivatives are excellent examples for decontamination due to their exceptional properties, especially the large surface area and chemical stability. The present study focused on the utilization of orange peel extract-assisted reduced graphene oxide (rGO) as a promising adsorbent for the removal of methylene blue (MB) dye. To synthesize rGO from graphene oxide (GO), orange peel extract serves as a reducing agent, offering a cost-effective, renewable, and environmentally friendly alternative. The green-synthesized rGO was characterized using UV-vis, FTIR, EDX spectroscopy, TG analysis, XRD, and TEM. These comprehensive analyses confirmed the effective reduction of GO and the successful formation of few-layered, exfoliated rGO nanosheets. The adsorption performance of the synthesized rGO for the removal of MB was assessed. The adsorption kinetics of MB on rGO can be best described by the pseudo-second-order kinetics model and the Langmuir model, which indicates that a chemisorption process governs the adsorption through a monolayer adsorption on the homogeneous surface of rGO. The maximum adsorption capacity is 82 mg/g, and the removal efficiency is 80%, which testifies to the suitability of the synthesized rGO as a promising adsorbent material.
This study presents the design of imidazole/urethane-functionalized silsesquioxane nanoparticles (SQNPs) that enable rapid self-healing through dynamic Zn-imidazole coordination and hydrogen bonds. Methylimidazole/hydroxyl-functionalized SQNPs (MI/OH-SQNPs) were prepared using epoxy-functionalized SQNPs and reacted with structurally diverse isocyanates, phenyl isocyanate (PU), hexamethylene diisocyanate (HMU), and methylenediphenyl diisocyanate (MDU), to yield MI/PU-, MI/HMU-, and MI/MDU-SQNPs, respectively. Extensive characterization (using nuclear magnetic resonance, Fourier-transform infrared (FT-IR) spectroscopy, size-exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction analysis, transmission electron microscopy, and atomic-force microscopy) showed a uniform dispersion of approximately 10 nm, an amorphous structure, excellent solubility, and good thermal stability (>230 degrees C). The drop-cast films of the imidazole/urethane-SQNP-Zn hybrids exhibited flexural moduli of 1.52, 1.86, and 4.08 GPa for MI/PU-, MI/HMU-, and MI/MDU-SQNPs, respectively, reflecting the effects of urethane linker rigidity, crosslink density, and covalent/noncovalent interactions. MI/PU-SQNP-Zn formed dual noncovalent networks combining hydrogen bonding and metal-ligand coordination, providing moderate stiffness with increased toughness. In contrast, MI/MDU-SQNP-Zn, which contained rigid aromatic segments, exhibited the highest modulus and strength. Zn coordination was confirmed via FT-IR spectroscopy, and transparent films (up to 99.6% transmittance at 400 nm) were produced. The formation of mechanically robust hybrid networks was confirmed via dynamic mechanical analysis, highlighting its ability to maintain structural integrity while allowing dynamic bond exchange. Scanning electron microscopy-energy dispersive spectroscopy confirmed the successful incorporation and uniform distribution of Zn within all hybrid networks. These Zn-complexed systems exhibited promising self-healing performances: MI/PU-, MI/HMU-, and MI/MDU-SQNP-Zn hybrids achieved similar to 87%, similar to 78.5%, and similar to 35% recovery of their mechanical integrity, respectively, which was governed by the flexibility or rigidity of the urethane segments. Additionally, MI/PU-SQNP-Zn demonstrated rapid thermal self-healing, recovering approximately 68% of its strength within 60 min at 50 degrees C and visibly healed in 10 s at 80 degrees C. These findings indicate that Zn-coordinated imidazole-urethane SQNPs offer a versatile platform for creating mechanically robust self-healing hybrid materials with promising applications in coatings, glassy materials, and functional composites.
Arbuscular mycorrhizal (AM) fungi change phosphorus (P) uptake and plant growth. The degree of change is defined as mycorrhizal dependency. Mycorrhizal dependency differs among cultivars and among different levels of soil P availability. The purpose of this study was to study the effect of AM fungus colonization on Allium fistulosum (A. fistulosum) with different mycorrhizal dependency grown at different levels of soil P availability. Twenty cultivars of A. fistulosum were grown with or without (control) AM fungus Rhizophagus spp. strain R-10 for 82 days. Three cultivars of A. fistulosum with different mycorrhizal dependency were inoculated and grown in soils fertilized at the rate of 0.43, 0.87, 2.18, and 4.36 g P kg-1 soil (P1, P2, P3, and P4, respectively) with or without (control) the AM fungus for 82 days. AM colonization, root length, shoot dry weight, and P concentration were determined. AM colonization increased shoot P content and shoot dry weight. Mycorrhizal dependencies were different among 20 cultivars and Mogamigawa, Shonan, and Kannonhosonegi were used as high, middle and low mycorrhizal dependency cultivars, respectively. Shoot P content of Mogamigawa and Shonan cultivars was higher in the inoculated plants than that in the uninoculated plants at P1, P2 and P3 soil fertilization rates. Shoot P content of the Kannonhoso was higher in the inoculated plants than that in the uninoculated plants at P1. Shoot dry weight of the Mogamigawa and Shonan was higher in the inoculated plant than that in the uninoculated plant at P1. These results suggest that selection of an appropriate cultivar and soil P availability are important factors in determining possible mutualistic, commensalistic, and parasitic relationships between the AM fungus and the host plant.
The hydrophilic nature and limited mechanical performance of thermoplastic starch (TPS) restrict its applicability compared with conventional plastics. This study improves the hydrophobicity and tensile properties of starch-based composites by incorporating epoxidized soybean oil (ESO) as a natural hydrophobic component through a reactive blending approach. Citric acid (CA) was used to promote crosslinking between starch and ESO. The molar ratio between carboxylic groups of CA and oxirane groups of ESO was varied from 0.2 to 1.0 to investigate its effects on phase dispersion and final performance. The reactive blending process enhanced hydrophobicity by up to 55% and improved compatibility through controlled crosslinking, as confirmed by FTIR mapping and DSC. Among all compositions, R0.6 demonstrated the most balanced crosslink network, resulting in the highest tensile strength at 4.4 MPa. These results demonstrate an effective strategy for preparing starch-based composites with improved hydrophobicity for food packaging applications.
