Durian Shell-Mediated Simple Green Synthesis of Nanocopper against Plant Pathogenic Fungi

The synthesis of fungicides in eco-friendly and cost-effective ways is significantly essential for agriculture. Plant pathogenic fungi cause many ecological and economic issues worldwide, which must be treated with effective fungicides. Here, this study proposes the biosynthesis of fungicides, which combines copper and Cu₂O nanoparticles (Cu/Cu₂O) synthesized using durian shell (DS) extract as a reducing agent in aqueous media. Sugar and polyphenol compounds contained in DS, as the main phytochemicals acting in the reduction procedure, were extracted under different temperatures and duration conditions to obtain the highest yields. We confirmed the extraction process performed at 70 °C for 60 min to be the most effective in extracting sugar (6.1 g/L) and polyphenols (22.7 mg/L). We determined the suitable conditions for Cu/Cu₂O synthesis using a DS extract as a reducing agent for a synthesis time of 90 min, a volume ratio of DR extract/Cu²⁺ of 15:35, an initial pH solution of 10, a synthesis temperature of 70 °C, and a CuSO₄ concentration of 10 mM. The characterization results of as-prepared Cu/Cu₂O NP showed a highly crystalline structure of Cu₂O and Cu with sizes estimated in the range of 40-25 nm and 25-30 nm, respectively. Through in vitro experiments, the antifungal efficacy of Cu/Cu₂O against Corynespora cassiicola and Neoscytalidium dimidiatum was investigated by the inhibition zone. The green-synthesized Cu/Cu₂O nanocomposites, which are potential antifungals against plant pathogens, exhibited excellent antifungal efficacy against both Corynespora cassiicola (MIC = 0.25 g/L, the diameter of the inhibition zone was 22.00 ± 0.52 mm) and Neoscytalidium dimidiatum (MIC = 0.0625 g/L, the diameter of the inhibition zone was 18.00 ± 0.58 mm). Cu/Cu₂O nanocomosites prepared in this study could be a valuable suggestion for the control of plant pathogenic fungi affecting crop species globally.

Hydroxyapatite Derived from Salmon Bone As Green Ecoefficient Support for Ceria-Doped Nickel Catalyst for CO2 Methanation

Hydroxyapatite (HA) derived from salmon bone byproducts is used as a green support for the nanostructured nickel catalysts applied in the methanation of carbon dioxide (CO₂). Undoped nickel catalysts and various ceria-doped nickel supported on hydroxyapatite (HA) were prepared by coimpregnation. Characteristics of the as-prepared catalysts were investigated by the various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), hydrogen temperature-programmed reduction (H₂-TPR), carbon dioxide temperature-programmed desorption (CO₂-TPD), and energy-dispersive X-ray spectroscopy (EDX). The catalyst activity was assessed throughout CO₂ methanation in the low-temperature range of 225-350 °C with the molar ratio of H₂/CO₂ = 4/1. The function of HA and ceria provided a high dispersity of nickel particles over the catalyst surface with the size range of 24.5-25.8 nm, leading to improvement in the reduction and CO₂ adsorption capacity of the catalysts as well as enhancing the catalytic efficiency in CO₂ methanation. The 10Ni/HA catalyst reduced at suitable conditions of 400 °C for 2 h showed the highest catalytic performance among the tested catalysts. CO₂ conversion and CH₄ selectivity reached 76.6 and 100% at a reaction temperature of 350 °C, respectively. The results show that the Ni/HA sample doped with 6.0 wt % ceria was the best, with the CO₂ conversion and the CH₄ selectivity reaching 92.5% and 100%, respectively, at a reaction temperature of 325 °C.

Green Orange Peel-Mediated Bioinspired Synthesis of Nanoselenium and Its Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus

In this study, green orange peel (GOP) was feasibly evidenced in preparing selenium nanoparticles (SeNPs). Acting as reducing agents, polyphenolic compounds were extracted from GOP at the optimal extraction conditions (at 70 °C for 1.5 h, mass ratio of dried orange peel/distilled water of 5/100). The formation of SeNPs was observed at the wavelength range of 250-300 nm by ultraviolet-visible spectroscopy (UV-vis), and their highest yield could be reached at the following conditions: volume ratio of extract/selenious acid solution (V _Ext/V _Se) of 40/10, synthesis duration of 4 h, selenious acid concentration (C _Se) of 80 mM, and reaction temperature of 120 °C. The highly crystalline structure of SeNPs in the hexagonal phase was characterized by powder X-ray diffraction (XRD) with a lattice parameter of 4.3 Å; meanwhile, their spheres with an average crystal size of 18.3 nm were estimated by high-resolution transmission electron microscope (HR-TEM). The rationale of bioreducing agents extracted from green orange peel for the formation of SeNPs was also recognized by Fourier-transform infrared spectroscopy (FT-IR). The antibacterial investigation of the SeNP sample was assessed against antibiotic-resistant bacteria, typically methicillin-resistant Staphylococcus aureus (MRSA), by executing the zone of inhibition and the minimum inhibitory concentration (MIC) tests. The SeNP sample demonstrated excellent antibacterial activity with an average diameter of inhibition zones of 20.0 ± 0.7 mm and an MIC of 4.94 μg/L. A comparison of the physicochemical properties of SeNPs synthesized from GOP extract by the hydrothermal method with SeNP products from other green reducing agents and other methods as well as its antibacterial activity compared with other nanoparticles and some antibiotics was conducted to highlight the superiority of GOP-mediated green-synthesized SeNPs.

Insights into the effects of synthesis techniques and crosslinking agents on the characteristics of cellulosic aerogels from Water Hyacinth

Aerogel cellulose materials were synthesised from Water hyacinth and different crosslinkers, such as kymene and a mixture of polyvinyl alcohol (PVA) and glutaraldehyde (GA). The effects of using a magnetic stirrer and ultrasonic methods were investigated. The results show that materials prepared using ultrasonic methods have higher porosity and lower density. The thermal conductivity of the synthesised aerogel cellulose could be as low as 0.0281 W m K⁻¹, showing the good heat insulation performance of this material. Absorption capacity was tested using diesel oil (DO), and the highest capacities of 58.82 and 52.03 g g⁻¹ of DO were found with kymene and PVA + GA as crosslinkers, respectively. The reusability of the materials was tested. After 10 cycles, the DO absorption capacity was 62.8% of the value of the first cycle for the aerogel cellulose sample with kymene as the crosslinker and 72.7% for the sample with PVA + GA as the crosslinking agent.

Aerogel cellulose materials were synthesised from Water hyacinth and different crosslinkers, such as kymene and a mixture of polyvinyl alcohol (PVA) and glutaraldehyde (GA).

High-efficiency reduction of p-nitrophenol on green-synthesized gold nanoparticles decorated on ceria nanorods

A green synthesis using extract from Citrus maxima peel was developed to fabricate Au–Ce catalysts for the reduction of p-nitrophenol (PNP). Au nanoparticles with a diameter of 6.6 ± 2.5 nm were deposited onto the surface of CeO₂ nanorods with a length of 33.1 ± 15.0 nm and a diameter of 7.1 ± 2.1 nm. The mesoporous and non-porous capillary structures of these materials were observed. The interaction between Au and CeO₂ increased the specific surface area, pore diameter, and pore volume compared with pure CeO₂ (90 m² g⁻¹, 23.8 Å, and 0.110 cm³ g⁻¹versus 72 m² g⁻¹, 23.0 Å, and 0.089 cm³ g⁻¹). The splitting peaks of the surface oxygen and their shifting at lower temperatures compared with CeO₂ nanorods were found thanks to the Au–CeO₂ interaction, suggesting that their reduction occurred more easily. The synthesized Au–Ce catalysts exhibited excellent activity in the reduction of PNP to p-aminophenol. The 0.2Au–Ce catalyst was the most efficient one for PNP reduction, enabling the conversion of PNP in 30 minutes with a catalyst concentration of 20 mg L⁻¹ and a PNP/NaBH₄ molar ratio of 1/200. Moreover, the 0.2Au–Ce catalyst could be reused for at least five consecutive cycles without considerable loss of its activity.

A green synthesis using extract from Citrus maxima peel was developed to fabricate Au–Ce catalysts for the reduction of p-nitrophenol (PNP).