Reduction Of P-nitroaniline Research Articles

Reduction of Nitroaromatics by Gold Nanoparticles on Porous Silicon Fabricated Using Metal-Assisted Chemical Etching.

In this study, we investigated the use of porous silicon (PSi) fabricated using metal-assisted chemical etching (MACE) as a substrate for the deposition of Au nanoparticles (NPs) for the reduction of nitroaromatic compounds. PSi provides a high surface area for the deposition of Au NPs, and MACE allows for the fabrication of a well-defined porous structure in a single step. We used the reduction of p-nitroaniline as a model reaction to evaluate the catalytic activity of Au NPs on PSi. The results indicate that the Au NPs on the PSi exhibited excellent catalytic activity, which was affected by the etching time. Overall, our results highlighted the potential of PSi fabricated using MACE as a substrate for the deposition of metal NPs for catalytic applications.

Facile and Green Synthesis of Carboxy Methyl Cellulose Stabilized Bio-Functionalized Gold Nanoparticles and Its Catalytic Activity

Gold nanoparticles (AuNP’s)are synthesized in sustainable green method using Carboxy Methyl Cellulose (CMC) and employed as catalyst in the reduction of p-nitro aniline with NaBH4 to p-phenylene diamine. It is observed that the speed of reaction was fast due to their size, as particle size decreases surface area increases. It is also observed that the rate of reaction is fast with comparison with the other catalyst. This is because the nanoparticles have more effective surface area and posses less steric hindrance with p-nitro aniline and NaBH4 when compared to nanoparticles due to their shape. The recyclability of nanoparticles shows it is potential recyclable catalyst for industrial applications.

Uniform fiber-like polymeric micelles of controlled length containing a photo-cleavable core: Versatile templates toward functional nanotubes

Inorganic nanotubes with unique and well-defined porous structures show promising applications in diverse functional materials. However, it remains a challenge to fabricate inorganic nanotubes with precise length controllability. Herein, we report the synthesis of block copolymers consisting of a crystalline π-conjugated oligo(p-phenylenevinylene) (OPV) block, a hydrophilic poly(2-vinylpyridine) (P2VP) segment and a photo-cleavable o-nitrobenzyl (ONB) junction. By taking advantage of crystallinity of OPV segment, self-seeding approach of living crystallization-driven self-assembly was employed to generate uniform fiber-like micelles composed of an OPV core and a P2VP corona. The P2VP corona was then used to host the formation of silica, titania and Pt(0)-embedded silica shell. After the photo-cleavable OBN junctions were broken under light irradiation, the OPV core can be removed in a good solvent for OPV segments to give silica, titania and Pt(0)-embedded silica nanotubes. Significantly, the Pt(0)-embedded silica nanotubes exhibited much higher catalytic activity toward the reduction of p-nitroaniline than Pt(0)-embedded silica nanofibers with the same Pt content, probably owing to the presence of porous channel for nanotubes. This work opens a new avenue to fabricate inorganic nanotubes of controlled length.

Enhanced catalytic properties of Fe3O4/Ag magnetic microspheres synthesized by a novel thermal co-reduction method

In this report, a highly dispersity and smaller size of Ag nanoparticles were directly embedded into/onto the hollow-porous Fe3O4 magnetic microspheres (Fe3O4/Ag MMPs) by a novel thermal co-reduction method, which used both NaBH4 and trisodium citrate dihydrate as reducing agent to reduce the AgNO3 to Ag nanoparticles. The structural, morphological and magnetic properties of the obtained Fe3O4 and Fe3O4/Ag MMPs were characterized by various techniques, including FT-IR, XRD, XPS, FE-SEM, TEM, VSM and so on. The catalytic performance of Fe3O4/Ag MMPs was examined towards the reduction of p-nitroaniline into p-phenylenediamine in fresh NaBH4 solution, which employing UV–vis spectrophotometer at 380 nm to continuously monitor the reaction progress. The characterization and experimental results indicated that Ag nanoparticles were successfully anchored both in the inner and outer of the hollow-porous Fe3O4 magnetic supports with a weight percent of 31.33%, in addition, the Fe3O4/Ag MMPs remained a high saturation magnetization value of 50.53 emu/g. More importantly, Fe3O4/Ag MMPs had excellent catalytic reduction properties, which fitted well with the first-order kinetics equation and the corresponding apparent rate constant k was 0.45 min−1. The enhanced catalytic properties of Fe3O4/Ag MMPs may be ascribed to the numerous loading of Ag nanoparticles, which were highly monodispersed and stable in an aqueous solution, as well as the remarkable synergistic effect between Ag nanoparticles and hollow-porous Fe3O4 magnetic microspheres.

Catalytic effect of silver particles supported on chitosan surface for the electrochemical sensing paranitroaniline at graphite electrode

ABSTRACT The present research <is conducted to develop a potent electrochemical sensor made of silver adsorbed on chitosan modified carbon paste (CS@Ag/CPE) for electrocatalytic reduction of p-nitroaniline (p-NA). The prepared electrode CS@Ag/CPE is characterized using different techniques including cyclic voltammetry (CV), Scanning electron microscopy, X-Ray diffraction analysis, Chronoamperometry and Electrochemical impedance spectroscopy (EIS). Electrochemical characterization demonstrates that the CS@Ag/CPE had excellent electrocatalytic activity, good electrical properties, and high active surface area. As compared with the unmodified carbon paste electrode, the modified electrode favours the reduction of p-NA and greatly enhances the peak current. Under the optimized condition, p-NA could be quantified within the range from 10.0 nM – 1.0 mM with a low detection limit of 7.87 nM according to (S/N = 3). The analytical performance of the developed sensor regards the detection of p-NA had been evaluated in practical samples including wastewater with satisfying results.

Shape-selective synthesis of gold nanoparticles and their catalytic activity towards reduction of p-nitroaniline

Microwave assisted shape-selective synthesis of gold nanoparticles has been achieved in a short reaction time of 6 min. Shape of the gold nanoparticles has been found to be tuneable among truncated cube, cube, tetrahedral and octahedral by changing the concentration of aqueous NaOH into the reaction mixture containing HAuCl4, N,N-dimethylformamide (DMF) and polyvinylpyrrolidone (PVP) under microwave irradiation. The preferential adsorption of sodium ions on gold surface during crystal growth controls the shape of the nanoparticles. The chemical state, crystallographic structure, elemental composition and morphology of the as-prepared gold nanoparticles were analyzed using respective XPS, powder XRD, EDS and FEG-SEM analytical techniques. Catalytic performance and recyclability of the as-prepared gold nanoparticles were examined towards the reduction of p-nitroaniline into p-phenylenediamine using sodium borohydride and continuous monitoring the reaction progress using UV-Visible spectrophotometer under ambient conditions.

Generation of biocompatible nanogold using H2O2–starch and their catalytic/antimicrobial activities

Biocompatible nanogold (AuNPs) have gained considerable attention for potential applications in nano-medicine due to their characteristic size dependent chemical, electronic and optical properties. Herein, energy saving and simple strategy was proposed for simultaneous preparation of nanogold suspension using starch polymer as bio-synthon and protective envelope for AuNPs, at room temperature·H2O2 was used as enhancer for the reducibility and accessibility of starch by oxidative degradation of its macromolecules to more reducible fragments. While, the nucleation of nanoparticles was motivated by the action of alkali. The reducible fragments in solution were detected via measurements of reducing sugars content. Preparation of nanogold was investigated by absorbance spectra, transmission microscope and zetasizer instrument. Size of AuNPs was a function of reactants' concentration and the smallest sized AuNPs (11.74nm) was produced by using 2g/L starch, 1% H2O2 and 10g/L NaOH, where, reducing sugars detected to be 0.46g/L. The produced nanogold showed good catalytic activity in reduction of p-nitroaniline and accelerate the reduction percentage from 12.1% to 39.2% in 2h. The prepared AuNPs displayed antibacterial efficacy towards different bacterial species and the MIC was evaluated to be 960µL/mL against S. aureus.

&lt;i&gt;Caesalpinia pulcherrima&lt;/i&gt; mediated green synthesis of silver nanoparticles: evaluation of their antimicrobial and catalytic activity

Plant extracts are an efficient, eco-friendly and cost-effective alternative source for the synthesis of nanoparticles. In this study, silver nanoparticles (AgNPs) were synthesized by treating the Caesalpinia pulcherrima (C. pulcherrima) leaf extract with aqueous solution of silver nitrate at room temperature. The biosynthesised AgNPs were characterised by techniques like transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and ultraviolet-visible spectroscopy (UV-Vis). The TEM analysis reveals the formation of spherical AgNPs with a diameter range of 30-50 nm. In vitro antimicrobial activity of the synthesized AgNPs was investigated against common human pathogens such as Pseudomonas aeruginosa (NCIM 5029), Serratia marcescens (NCIM 2078), Staphylococcus aureus (NCIM 5021) and Salmonella typhimurium (NCIM 2501) by agar well diffusion method. The synthesized AgNPs showed potential antimicrobial activity against all of the mentioned bacterial cultures. Furthermore, current study have shown the catalytic degradation of methylene blue dye and reduction of p-nitroaniline using synthesized AgNPs. Synthesised nanoparticles have shown excellent catalytic activity within a very short time period.

Catalytic Application of Synthesized Capped Silver Nanoparticles for Reduction of p-Nitroaniline

Catalytic Application of Synthesized Capped Silver Nanoparticles for Reduction of p-Nitroaniline

Template synthesis of braided gold nanowires with gemini surfactant–HAuCl4 aggregates

One-dimensional braided gold nanowires with 40–50 nm in width and several micrometers in length which were fabricated by using cationic gemini surfactant hexamethylene-1,6-bis (dodecyl dimethylammonium bromide) (C12C6C12Br2). Through simply regulating the mole ratio of C12C6C12Br2 to HAuCl4, the morphology of the gold products changed into nanoparticles and nanowires. The CryoTEM images indicated that the C12C6C12Br2/HAuCl4 mixture formed spherical or fibrillar aggregates depending on the mole ratio of C12C6C12Br2 to HAuCl4, which performed as the versatile templates for morphology-controlled synthesis of the multiple gold nanomaterials. The HRTEM and SAED results suggested the nanowires and braided nanowires were polycrystalline. The gold nanostructure displayed a time-dependent growth process, i.e., first the nanoparticles arranged in one dimension, and then assembled into nanowires. Therefore, a template-directed aggregation and fusion process of nanoparticles is proposed for the formation of the one-dimensional gold nanomaterials. The braided nanowires exhibited a higher catalytic activity in the reduction of p-nitroaniline than that of the nanowires. This gemini surfactant-based template provides a versatile strategy for the morphology-controlled synthesis of gold nanomaterials, and may be applied for the synthesis of other noble-metal nanomaterials.

Effects of the nickel oxide on the hydrogen evolution and para-nitroaniline reduction at Ni-deposited graphite electrodes in NaOH

Abstract The reduction of p-nitroaniline (PNA) by electrocatalytic hydrogenation (ECH) as well as the evolution and adsorption of hydrogen were found to be depressed by the formation of irreducible β-Ni(OH)2 or NiO at nickel-deposited graphite (Ni/C) electrodes. An increase in the Tafel slope from 120 to 200 mV dec−1 in the low overpotential region of the hydrogen evolution reaction (HER) suggested that: (i) the HER mechanism on β-Ni(OH)2/NiO is different from the Volmer–Heyrovsky–Tafel reactions or (ii) the reduction of these oxides predominates in this potential range. X-ray diffraction (XRD) results revealed that NiO was formed on the Ni/C electrode surface after it had been annealed in air at 400°C for 1 h. High-performance liquid chromatography (HPLC) results revealed that on the Ni/C electrodes before and after annealing treatment and on the pure Pt electrode, p-phenylenediamine (PPDA) is one of the major products in the PNA reduction and the selectivity of PPDA formation is the highest on pure Pt.

Indirect reduction of p-nitroaniline to p-phenylenediamine at a Ti/TiO2 electrode

Indirect reduction of p-nitroaniline to p-phenylenediamine at a Ti/TiO2 electrode

Polarographic oxidation and reduction of p-nitroaniline at carbon paste electrodes

One of the most valuable features of carbon paste electrodes is the wide potential range available for both anodic and cathodic reactions. In the present study both the oxidation of the amino group and the reduction of the nitro function on p-nitroaniline are examined. The ratio of the limiting currents, i c/i a , is close to 3. The nitro reduction was shown to be a 6-electron process using the technique of cyclic voltammetry. Thus, it is established that the amine oxidation is an overall ( n T ) 2-electron process. This novel determination of n t using such a bi-functional molecule does not require the diffusion coefficient to be known and may be applicable to other solid electrode mechanism studies.