An efficient and blistering reduction of 4-nitrophenol by green synthesized silver nanoparticles

Magnetically recoverable sol-gel auto-combustion developed Ni1-xCuxDyyFe2-yO4 magnetic nanoparticles for photocatalytic, electrocatalytic, and antibacterial applications

Copper and dysprosium doped NiFe₂O₄ magnetic nanomaterials, Ni_1-xCu_xDy_yFe_2-yO₄ (x = y = 0.00, 0.01, 0.02, 0.03), was prepared by utilizing sol-gel auto-combustion approach to inspect the photodegradation of methylene blue (MB) pollutant and also, to perform the electrocatalytic water splitting and antibacterial studies. The XRD analysis reveal the growth of a single-phase spinel cubic structure for produced nanomaterials. The magnetic traits show an increasing trend in saturation magnetization (M_s) from 40.71 to 47.90 emu/g along with a decreasing behaviour of coercivity from 158.09 to 142.31 Oe at lower and higher Cu and Dy doping content (x = 0.0-0.01). The study of optical band gap values of copper and dysprosium-doped nickel nanomaterials decreased from 1.71 to 1.52 eV. This will increase the photocatalytic degradation of methylene blue pollutant from 88.57% to 93.67% under natural sunlight, respectively. These findings clearly show that under natural sunlight irradiation for 60 min, the produced N4 photocatalyst displays the greatest photocatalytic activity with a maximum removal percentage of 93.67%. The electrocatalytic characteristics of produced magnetic nanomaterials for both HER and OER were examined with a Calomel electrode taking as a reference in a 0.5 N H₂SO₄ and 0.1 N KOH electrolyte. The N4 electrode demonstrated considerable 10 and 0.024 mA/cm² of current density, with onset potentials of 0.99 and 1.5 V for HER and OER and also, have tafel slopes of 58.04 and 295 mV/dec, respectively. The antibacterial activity for produced magnetic nanomaterials was examined against various bacteria (Bacillus subtilis, Staphylococcus aureus, S. typhi, and P. aeruginosa) in which N3 sample produced significant inhibition zone against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) but no zone of inhibition against gram-negative bacteria (S. typhi and P. aeruginosa). With all these superior traits, the produced magnetic nanomaterials are highly valuable for the wastewater remediation, hydrogen evolution, and biological applications.

Comprehensive Study on Lemon Juice-Based Green Synthesis and Catalytic Activity of Bismuth Nanoparticles

Bismuth nanoparticles have gained considerable interest in catalysis because of their small size, large surface-to-volume ratio, and low toxicity. In spite of these advantages, the toxic reagents and solvents used in the synthetic process are significant limitations to their development and utilization. In this study, a green approach employing easily accessible lemon juice was applied for the synthesis of bismuth nanoparticles (BiNPs) as a green alternative to conventional chemical ones. This study clarified the formation and growing process of green-synthesized BiNPs using lemon juice as a reducing and capping agent. The reaction time and amounts of lemon juice significantly affect the growth, morphology, and stability of BiNPs, as confirmed from XRD, DLS, SEM, and TEM analyses. The synthesized BiNPs effectively catalyzed the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH₄, and the reduction was significantly accelerated by sunlight and the removal of the fibrous coating layer around BiNPs. Moreover, the synthesized BiNPs also show excellent catalytic efficacy toward the reduction of organic dyes, namely, methyl orange, methylene blue, and rhodamine B. All catalytic reductions followed the pseudo-first-order kinetics, and the rate constants are in the order of k _MB > k _RhB > k _MO > k _4-NP. The stated biogenic synthetic route paves the way for the green industrial fabrication of BiNPs and their uses in catalysis for wastewater treatment.

Green in situ immobilization of gold and silver nanoparticles on bacterial nanocellulose film using Punica granatum peels extract and their application as reusable catalysts

In this study, Punica granatum peels extract induced in situ deposition was applied to prepare Au and Ag nanoparticles on bacterial nanocellulose film. Bacterial nanocellulose provided as an eco-friendly and excellent support for the interaction of P. granatum peel biomolecules and further reduction of Au and Ag ions. Meanwhile, a possible in situ growth mechanism of Au and Ag on bacterial cellulose by P. granatum peel extract biomolecules was presented. Further, the metal nanoparticles incorporated bacterial cellulose films were used to catalyze the reduction of 4-nitrophenol. The results of the present study indicated excellent catalytic reduction properties of Au and Ag nanocellulose films for 4 consecutive cycles. In addition, Au and Ag incorporated cellulose nanofiber films exhibited superior antioxidant activity and improved mechanical properties compared to pristine cellulose nanofiber film. The findings of this study may provide new insights and broad application of bacterial cellulose and green synthesis method for the development of various metal-cellulose composites.

Ag nanoparticles supported on a magnetic NiFe2O4/MIL-101(Fe) metal–organic framework nanocomposite for the room temperature rapid catalytic reduction of nitrophenols and nitroanilines

A novel Ag@NiFe2O4/MIL101(Fe) ternary magnetic nanocomposite was synthesized for the room temperature rapid catalytic reduction of nitrophenols and nitroanilines.

Reduction of 4-nitrophenol using green-fabricated metal nanoparticles

Noble metal (silver (Ag), gold (Au), platinum (Pt), and palladium (Pd)) nanoparticles have gained increasing attention due to their importance in several research fields such as environmental and medical research. This review focuses on the basic perceptions of the green synthesis of metal nanoparticles and their supported-catalyst-based reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The mechanisms for the formation of these nanoparticles and the catalytic reduction of 4-NP are discussed. Furthermore, the parameters that need to be considered in the catalytic efficiency calculations and perspectives for future studies are also discussed.

Noble metal (silver (Ag), gold (Au), platinum (Pt), and palladium (Pd)) nanoparticles have gained increasing attention due to their importance in several research fields such as environmental and medical research.

Investigation of TiO2 Nanoparticles Synthesized by Sol-Gel Method for Effectual Photodegradation, Oxidation and Reduction Reaction

Metal oxide titanium dioxide (TiO2) nanoparticles were synthesized by using a simple and economical sol-gel method. The prepared nanoparticles were used to evaluate methylene blue dye degradation and as catalysts in the oxidation of benzaldehyde. The crystallite size of the titanium dioxide nanoparticle was 18.3 nm, which was confirmed by X-ray diffraction analysis. The spherical morphology was confirmed by scanning electron microscopy (SEM), and the elemental composition of the nanoparticle was found by energy dispersive X-ray (EDAX) analysis. The anatase form of the nanoparticle was confirmed by the bandgap 3.2 eV, which was measured using UV–DRS analysis. The bond between metal and oxygen was confirmed by the peaks at 485 and 606 cm–1 analyzed by Fourier transform infrared analysis (FTIR). The efficiency of the catalyst in dye degradation was 60.08, 68.38, and 80.89% with respect to 50, 75, and 100 mg catalyst weight. The yield % of benzoic acid was 94%, and the reduction efficiency against 4-nitrophenol was 98.44%.

Phytoassisted synthesis of magnesium oxide nanoparticles from Pterocarpus marsupium rox.b heartwood extract and its biomedical applications

BACKGROUND

Unlike chemical techniques, the combination of metal oxide nanoparticles utilizing plant concentrate is a promising choice. The purpose of this work was to synthesize magnesium oxide nanoparticles (MgO-NPs) utilizing heartwood aqueous extract of Pterocarpus marsupium. The heartwood extract of Pterocarpus marsupium is rich in polyphenolic compounds and flavonoids that can be used as a green source for large-scale, simple, and eco-friendly production of MgO-NPs. The phytoassisted synthesis of MgO is characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with EDS (energy dispersive X-ray spectroscopy), and transmission electron microscopy (TEM).

RESULTS

The formation of MgO-NPs is confirmed by a visual color change from colorless to dark brown and they displayed a wavelength of 310 nm in UV-Spectrophotometry analysis. The crystalline nature of the obtained biosynthesized nanoparticles are revealed by X-ray diffraction analysis. SEM results revealed the synthesized magnesium oxide nanoparticles formed by this cost-effective method are spherically shaped with an average size of < 20 nm. The presence of magnesium and oxygen were confirmed by the EDS data. TEM analysis proved the spherical shape of the nanoparticles with average particle size of 13.28 nm and SAED analysis confirms the crystalline nature of MgO-NPs. FT-IR investigation confirms the existence of the active compounds required to stabilize the magnesium oxide nanoparticles with hydroxyl and carboxyl and phenolic groups that act as reducing, stabilizing, and capping agent. All the nanoparticles vary in particle sizes between 15 and 25 nm and obtained a polydispersity index value of 0.248. The zeta-potential was measured and found to be - 2.9 mV. Further, MgO-NPs were tested for antibacterial action against Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) by minimum inhibitory concentration technique were found to be potent against both the bacteria. The blended nanoparticles showed good antioxidant activity examined by the DPPH radical scavenging method, showed good anti-diabetic activity determined by alpha-amylase inhibitory activity, and displayed strong anti-inflammatory activity evaluated by the albumin denaturation method.

CONCLUSIONS

The investigation reports the eco-friendly, cost-effective method for synthesizing magnesium oxide nanoparticles from Pterocarpus marsupium Rox.b heartwood extract with biomedical applications.

Eco-friendly synthesis of lignin mediated silver nanoparticles as a selective sensor and their catalytic removal of aromatic toxic nitro compounds

The development of an eco-friendly and reliable process for the production of nanomaterials is essential to overcome the toxicity and exorbitant cost of conventional methods. As such, a facile and green synthesis method is introduced for the preparation of lignin mediated silver nanoparticles (L-Ag NPs). This is produced by reducing Ag precursors using lignin biopolymers which are formulated by pulsed laser irradiation and an ultrasonication process. Lignin operates as both a reducing and stabilizing agent. The various analytical techniques of ultraviolet-visible spectroscopy, transmission electron microscope and X-ray diffractometer studies were employed to verify the formation of non-aggregated spherical L-Ag NPs with an average size as small as 7-8 nm. The selective sensing capability of the synthesized L-Ag NPs was examined for the detection of hydrogen peroxide and mercury ions in an aqueous environment. Furthermore, the superior catalytic performance of L-Ag NPs was demonstrated by the rapid conversion of toxic 4-nitrophenol and nitrobenzene as targeted pollutants to the corresponding amino compounds. A plausible catalytic reduction mechanism for the removal of toxic nitro-organic pollutants over L-Ag NPs is proposed. This research coincides with existing studies and affirms that L-Ag NPs are an effective sensor that be applied as a catalytic material within environmental remediation and also alternative biomedical applications.