Rapid Chemical Method Research Articles

A rapid and simple chemical method for the preparation of Ag colloids for surface-enhanced Raman spectroscopy using the Ag mirror reaction

Colloidal silver (Ag) nanoparticles (AgNP) have been widely used for surface-enhanced Raman spectroscopy (SERS) applications. We report a simple, rapid and effective method to prepare AgNP colloids for SERS using the classic organic chemistry Ag mirror reaction with Tollens’ reagent. The AgNP colloid prepared with this process was characterized using SEM, and the reaction conditions further optimized using SERS measurements. It was found that Ag mirror reaction conditions that included 20 mM AgNO3, 5 min reaction time, and 0.5 M glucose produced AgNP colloids with an average size of 319.1 nm (s.d ± 128.1). These AgNP colloids exhibited a significant SERS response when adenine was used as the reporter molecule. The usefulness of these new AgNP colloids was demonstrated by detecting the nucleotides adenosine 5′-mono-phosphate (AMP), guanosine 5′-monophosphate (GMP), cytidine 5′-monophosphate (CMP), and uridine 5′-monophosphate (UMP). A detection limit of 500 nM for AMP was achieved with the as-prepared AgNP colloid. The bacterium Mycoplasma pneumoniae was also easily detected in laboratory culture with these SERS substrates. These findings attest to the applicability of this AgNP colloid for the sensitive and specific detection of both small biomolecules and microorganisms.

Photocatalytic activity of CuO/Cu(OH)2 nanostructures in the degradation of Reactive Green 19A and textile effluent, phytotoxicity studies and their biogenic properties (antibacterial and anticancer)

In this study, CuO/Cu(OH)2 (denoted as CuONs) nanostructures were synthesized relying to a cheap and rapid chemical co-precipitation method using copper sulfate and liquid ammonia as precursors. Results obtained from X-ray diffraction, and field emission scanning electron microscopy analysis revealed the crystalline nature of synthesized CuONs. Fourier transform infrared spectroscopy and energy dispersive spectroscopy studies showed interactions between copper and oxygen atoms. Synthesized CuONs showed the size in the range of 20–30 nm using high resolution transmission electron microscopy analysis. The photocatalytic degradation performance of Reactive Green 19A (RG19A) dye using CuONs was evaluated. The results showed that CuONs exhibited 98% degradation efficiency after 12 h and also complete mineralization in form of reducing chemical oxygen demand (COD) (84%) and total organic carbon (TOC) (80%). The nanocatalyst was recovered from the dye containing solution and its catalytic activity can be reused up to four times efficiently. CuONs was also able to decolorize actual textile effluent (80% in terms of the American Dye Manufacturers' Institute (ADMI) value) with significant reductions in COD (72%) and TOC (69%). Phytotoxicity studies revealed that the degradation products of RG19A and textile effluent were scarcely toxic in nature, thereby increasing the applicability of CuONs for the treatment of textile wastewater. Additionally, the CuONs showed a maximum antibacterial effect against human pathogens which also displayed synergistic antibacterial potential related to commercial antibiotics. Moreover, CuONs displayed strong antioxidant activity in terms of ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (IC50: 51 μg/mL) and DPPH (1,1-diphenyl-2-picrylhydrazyl) (IC50: 60 μg/mL) radical scavenging. The CuONs exhibited dose dependent response against tumor rat C6 cell line (IC50: 60 μg/mL) and may serve as anticancer agents.

An insight into formation mechanism of rapid chemical Co-precipitation for synthesizing yttrium iron garnet nano powders

The rapid chemical co-precipitation method is supposed to be a stable way to synthesize high quality cubic yttrium iron garnet (YIG) nanopowders. In this paper, focusing on clarifying its formation mechanism, the thermal behaviors and the elemental distributions of the chemical co-precipitated precursors have been analyzed by simultaneous differential scanning calorimetry plus thermal gravimetric analysis (DSC-TGA) and energy disperse spectroscopy (EDS) mapping technique on a transmission electronic microscope. The results indicated that the homogeneity of Y and Fe elemental distributions in the precursor powders determines the process through which the cubic YIG phase would form: one experiences the intermediate tetragonal YIG phase; the other takes YFeO3 as the intermediate phase. The homogenous distributions of Y and Fe elements in the precursor powders at the scale below 50 nm forms the intermediate tetragonal YIG phase rather than YFeO3, which leads to reduction of the formation temperature for synthesizing the single phase YIG. The obtained YIG nanopowders with the average particle size below 100 nm show excellent magnetic properties with saturation magnetization of 26 emu/g and coercive field of 45 Oe. This clear formation mechanism of YIG nanopowders is suitable for optimizing the processing conditions for the chemical precipitation synthesis of YIG nanopowders at large scale.

Bi2Te3 Nanorods: Preparation, Reaction Mechanism and Electrochemical Property

A rapid chemical method has been developed for the synthesis of the Bi2Te3 nanorods with hexagonal crystalline phase. The method is based on the template-engaged synthesis in which the Te nanowires were used as template reagents. On the basis of a series of experiments and characterizations, the effect factors and the formation mechanism of the Bi2Te3 nanorods were discussed. Furthermore, the electrochemical property of the Bi2Te3 nanorods was determined by the voltammetric technique.

Preparation and high-performance microwave absorption of hierarchical dendrite-like Co superstructures self-assembly of nanoflakes

Dendritic-like Co superstructures based on the self-assembly of nanoflakes that could efficiently suppress the eddy current were successfully synthesized via a facile, rapid, and energy-saving chemical reduction method. Since crystal structure, size, and special geometrical morphology, magnetism have a vital influence on microwave absorption properties, the as-obtained products were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The prepared dendritic Co possesses abundant secondary branches that extend to the 3D space. Their dimensions, spacing, sheet-like blocks, and high-ordering microstructures all contribute to the penetration, scattering, and attenuation of EM waves. The composites present attractive microwave absorption performances in the X band, as well as in the whole S band (2–4 GHz). This work investigates the mechanism of absorption for the as-obtained Co, offers a promising strategy for the fabrication of hierarchical Co microstructure assemblies by multi-leaf flakes and introduces the application of dendritic-like Co as a highly efficient absorber in the S band and X band.

Breakdown of plastic waste into economically valuable carbon resources: Rapid and effective chemical treatment of polyvinylchloride with the Fenton catalyst

Polyvinylchloride (PVC) is a typical non-biodegradable plastic that is resistant to chemicals, sunlight, and weathering. These properties make its disposal problematic, as items made from PVC retain their form for decades. The objective of this study is to provide an effective waste management method for the degradation of huge amounts of the robust plastic waste. In this work, a rapid chemical treatment method has been developed by utilizing the Fenton catalyst to break down PVC plastic wastes into recoverable high-value organic compounds. During this chemical process, surface activation of PVC takes place to generate coordinating sulfonate groups that get tagged with iron(III) chloride. The iron(III)-tagged PVC is a highly active Fenton catalyst that breaks down the entire bulk polymer into a number of valued organic acids selectively using hydrogen peroxide as a green oxidant. By using this procedure, all treated PVC plastic wastes were completely degraded into water soluble organic compounds and CO2 under ambient dark conditions within 10 min. The dissolved organic compounds were identified mainly as mono- and dicarboxylic acids. The formation of these products indicates that the reaction is selective, which is not expected from the classical Fenton-type radical oxidation reactions. A detailed study was conducted to probe the possible mechanism of degradation that takes place during the chemical treatment process. It was found that the temperature conditions for PVC activation significantly affect the number of activated sites (sulfonated groups) generated on the polymer backbone, in which the carbon-to-sulphur atom (C/S) ratio can vary from 8:1 to 29:1. The degradation efficiency, which is typically defined in terms of the bulk mass of the treated PVC plastics, was found to be greater than 98% in all cases. This also included the real samples of rigid PVC pipe. The recovered amount of the characteristic compound butanedioic acid, which is formed during the PVC plastic breakdown process, was found to consistently vary from 9.8% to 61.3% with respect to the C/S ratio. The results of this study are also helpful for the further development of similarly fast and effective plastic waste treatment and management protocols in lieu of landfill disposal, which is particularly important for polymers such as polyethylene (PE), and polypropylene (PP).

The use of biodegradable polymers for the stabilization of copper nanoparticles synthesized by chemical reduction method

Copper nanoparticles were synthesized by a convenient and rapid chemical reduction method in ambient condition using $$\hbox {Cu}(\hbox {NO}_{3})_{2}{\cdot } 3\hbox {H}_{2}\hbox {O}$$ as a precursor, hydrazine hydrate as reducing agent and deionized water as solvent. The product was characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. However, agglomerated copper nanoparticles were obtained by this chemical reduction method. Hence, the effects of three polymers of polyvinyl pyrrolidone, polyethylene glycol (PEG) and starch as stabilizers on the size and size distribution of Cu nanoparticles were investigated. According to the results, smallest copper nanoparticles (30–50 nm) with a narrow size distribution were obtained using PEG as the stabilizing polymer. Zero-valent copper nanoparticles with high purity were obtained by this method and there was no peak related to the oxidized impurities such as CuO and $$\hbox {Cu}_{2}\hbox {O}$$ in the XRD and UV–Vis studies, both in the presence and in the absence of stabilizer. On the other hand, by this method, zero-valent copper nanoparticles were obtained in the absence of any anti-oxidant agent and any inert gas flow. The effects of synthesis parameters including initial concentration of precursor, polymer concentration and the reaction temperature on the size and size distribution of copper nanoparticles were investigated using the UV–Vis analysis to determine the optimum synthesis conditions.

Synthesis and characterization of inorganic mixed metal oxide nanoparticles derived from Zn–Al layered double hydroxide and their antibacterial activity

Inorganic metal oxides represent a class of materials that have been used for health applications. In this research, a series of novel environmental-friendly mixed metal oxide nanoparticles with general formula ZnO/MAl2O4 (M= Cu, Ni, Co and Mg) were synthesized by mixing Zn–Al layered double hydroxide as precursor with various metal nitrate salts. For this purpose, in the first step, the Zn–Al layered double hydroxide (Zn–Al LDH) as precursor was synthesized by a simple and rapid chemical co-precipitation method. In the second step, by simple mixing of Zn–Al LDH compound as precursor with related metal nitrate salts M (NO3)2. xH2O (M= Cu, Ni, Mg and Co), the mixed metal oxide nanoparticles of ZnO/CuAl2O4, ZnO/NiAl2O4, ZnO/CoAl2O4, and ZnO/MgAl2O4 were synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–vis diffusive reflectance spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Furthermore, the antibacterial activity of the synthesized mixed metal oxides was evaluated against the gram-negative bacterial species Escherichia coli and the gram-positive bacterial species Staphylococcus aureus. The crystallite size and play a critical role. Thus, the antibacterial activity of the mixed metal oxides was demonstrated to be in the following order: ZnO/NiAl2O4 > ZnO/CuAl2O4 > ZnO/MgAl2O4 > ZnO/CoAl2O4.

Cellulose-derived carbon aerogels supported goethite (α-FeOOH) nanoneedles and nanoflowers for electromagnetic interference shielding

We describe a rapid and facile chemical precipitation method to grow goethite (α-FeOOH) nanoneedles and nanoflowers on the carbon aerogels which was obtained from the pyrolysis of cellulose aerogels. When evaluated as electromagnetic interference (EMI) shielding materials, the α-FeOOH/cellulose-derived carbon aerogels composite displays the highest SEtotal value of 34.0dB at the Fe3+/Fe2+ concentration of 0.01M, which is about 4.8 times higher than that of the individual α-FeOOH (5.9dB). When the higher or lower Fe3+/Fe2+ concentrations were used, the EMI shielding performance deterioration occurred. The integration of α-FeOOH with the carbon aerogels transforms the reflection-dominant mechanism for α-FeOOH into the adsorption-dominant mechanism for the composite. The adsorption-dominant mechanism undoubtedly makes contribution to alleviating secondary radiation, which is regarded as more attractive alternative for developing electromagnetic radiation protection products.

Novel chemical synthesis and characterization of copper pyrovanadate nanoparticles and its influence on the flame retardancy of polymeric nanocomposites.

In this work, copper pyrovanadate (Cu3V2O7(OH)2(H2O)2) nanoparticles have been synthesized by a simple and rapid chemical precipitation method. Different copper-organic complexes were used to control the size and morphology of products. The morphology and structure of the as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrum, electron dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and photoluminescence (PL) spectroscopy. The influence of copper pyrovanadate nanostructures on the flame retardancy of the polystyrene, poly vinyl alcohol and cellulose acetate was studied. Dispersed nanoparticles play the role of a magnetic barrier layer, which slows down product volatilization and prevents the flame and oxygen from the sample during decomposition of the polymer. Cu3V2O7(OH)2(H2O)2 is converted to Cu3V2O8 with an endothermic reaction which simultaneously releases water and decrease the temperature of the flame region.

Epitaxy-driven vertical growth of single-crystalline cobalt nanowire arrays by chemical vapor deposition

Ferromagnetic single-crystalline Co nanowires (NWs) aligned in a vertical orientation are epitaxially grown on m-cut sapphire substrates by a rapid and versatile chemical vapor deposition method. They were transformed into Co3O4 nanotubes by thermal annealing under dilute O2 conditions.

Carbon- and Polyaniline Nanofibers Containing Composite Electrode Material for Supercapacitors.

Rapid mixing chemical oxidative polymerization method is used to synthesize carbon nanofibers (CNFs) and polyaniline nanofibers (PANI NF) containing composite. Morphological, structural and phase analyses reveal that the composite is constituted by PANI coated CNFs and PANI NF. The intrinsic defects on the CNFs' surfaces allowed the nucleation and growth of PANI on them. At the same time, the use of optimal aniline concentration facilitated the simultaneous nucleation and growth of PANI NF The composite exhibits an excellent electrochemical activity with a specific capacitance of -156.92 F/g. The synergic contribution of the constituents to the overall electrochemical activity of the composite are identified.

Facile assembly of Ni-Co hydroxide nanoflakes on carbon nanotube network with highly electrochemical capacitive performance.

Herein, we demonstrate the high-density assembly of Ni-Co hydroxide nanoflakes on conductive carbon nanotube (CNT) network through a simple and rapid chemical precipitation method, presenting a low-cost and high-performance scaffold for pseudosupercapacitor. It is found that the Ni-Co layered double hydroxide (LDH) nanoflakes prefer to proliferate around large-diameter CNTs (diameter>50 nm), with conductive CNT network well-maintained. Such hierarchical nanostructures show greatly improved specific surface areas compared with bare CNT network and are freestanding without other organic binder, which can be directly employed as a binder-free compact electrode assembly. By optimizing the chemical composition of as-precipitated LDH nanoflakes, the resultant Co0.4Ni0.6(OH)2 LDH/CNT composite nanostructures exhibit the largest specific electrochemical capacitance and the best rate performance, with their capacitance up to 1843 F/g under a low current density of 0.5 A/g and maintained at 1231 F/g when the current density is increased 20 times to 10 A/g. Importantly, such hierarchical nanostructures tend to prevent the electrode from severe structural damage and capacity loss during hundreds of charge/discharge under a high rate (2 A/g), ensuring the electrode with high-energy density (51 W h/kg) at power density of 3.3 kW/kg.

Simple and rapid colorimetric detection of p-nitrophenyl substituent organophosphorous nerve agents

We report a very simple and rapid chemical method for the detection of paraoxon and its p-nitrophenyl organophosphorous derivatives. The method uses only sodium borohydride followed by thermal enhancement that increases the sensitivity by two orders of magnitude. Visible, yellow color change of the neurotoxins caused by p-nitrophenolate ions can be rapidly observed at micromolar concentrations while UV–vis measurements enable unprecedented detection at the nanomolar level.

Simple and rapid green synthesis of micrometer scale single crystalline gold nanoplates using chitosan as the reducing agent

A simple, rapid and green chemical method for the synthesis of single crystalline gold nanoplates of several micrometeres in size has been demonstrated. The synthesis involved the reduction of HAuCl4 in aqueous solution using low molecular weight chitosan at boiling temperature for 25min. The [Au3+]:[chitosan] molar ratio plays an important role in the formation of gold nanoplates and found that an optimized molar ratio in the range of 80 to 125 was suitable for the formation of nanoplates. The size and morphology of the nanoplates can be tuned by adjusting the molar ratio. In this process, the chitosan functions both as a reducing as well as a stabilizing agent and no other special agents were added to induce the nanoplate formation. The obtained nanoplates were single crystals with (111) planes as the basal planes with shapes of hexagonal, triangular, or truncated triangular plates.

Rapid mixing chemical oxidative polymerization: an easy route to prepare PANI coated small-diameter CNTs/PANI nanofibres composite thin film

Composite thin film containing polyaniline (PANI) coated small diameter carbon nanotubes (SDCNTs)/PANI nanofibres (NFs) has been prepared using an easy in situ rapid mixing chemical oxidative polymerization method. SDCNTs thin film was obtained using thermal chemical vapour deposition method in a separate experiment, whilst PANI NFs are formed in situ during the synthesis of composite. In the composite, PANI coated SDCNTs are uniformly distributed among PANI NFs. The presence of SDCNTs during the composite synthesis does not influence the nucleation and growth of PANI NFs. Raman analysis shows a good interaction between PANI and SDCNTs. Room temperature d.c. electrical sheet resistance of SDCNTs/PANI NFs composite thin film surface is three orders lesser than that of PANI NFs thin film (PANI NFs have the same morphology as in the composite) synthesized using the same method but without the presence of SDCNTs.

Facile method for the synthesis of silver nanoparticles using 3-hydrazino-isatin derivatives in aqueous methanol and their antibacterial activity

IntroductionA new method for preparation of silver nanoparticles (AgNPs) based on using hydrazino-isatin derivatives in an aqueous methanol reaction medium is reported here. AgNPs were prepared using silver nitrate solubilized in a water core as the source of silver ions and 3-hydrazino-isatin derivatives (3-hydrazino-isatin [IsH] and 1-benzyl-3-hydrazino-isatin [BIsH]) solubilized in methanol core as a reducing agent. The proposed method is effective, rapid, and convenient. X-ray diffraction (XRD), energy dispersive X-ray analysis, scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used for characterization of the AgNPs. The TEM micrographs confirmed that the nanopowders consist of well-dispersed agglomerates of grains with a narrow size distribution of 18–21 nm and 17–20 nm. The AgNPs, as well as BIsH, showed high antimicrobial and bactericidal activity against the Gram-positive Bacillus subtilis and Gram-negative Micrococcus luteus and Proteus vulgaris, as well as antifungal activities against Saccharomyces cerevisiae. On the other hand, they were not effective against the Gram-negative Escherichia coli.PurposeA simple, effective, rapid, and convenient chemical reduction method for the synthesis of AgNPs in an aqueous methanol reaction medium using hydrazino-isatin derivatives and studying their antibacterial effect.ResultsIsH and BIsH are remarkably powerful reductants for Ag+ ions in an aqueous methanol medium, which could be considered as a simple chemical reduction method for formation of AgNPs. The AgNP formation depends on the solubility of the hydrazino-isatin derivatives. BIsH gave more AgNPs than IsH, as observed from XRD. The formation of AgNPs is attributed to the adsorption of hydrazine derivatives and/or interparticle interaction on the surface of AgNP through electrostatic interactions between the lone pair electrons of the hydrazino group (C=N-NH2) and the positive surface of AgNPs. AgNPs and BIsH showed high antimicrobial and bacterial activity.ConclusionIn summary, it is shown that IsH and BIsH are remarkably powerful reductants for Ag+ ions in an aqueous methanol medium. BIsH gave more AgNPs than IsH, as observed from XRD due to better solubility of the BIsH than IsH in aqueous-methanol. The formation of AgNPs is attributed to the adsorption of hydrazine derivatives and/or interparticle interaction on the surface of AgNPs through electrostatic interactions between the lone pair electrons of the hydrazino group (C=N-NH2) and the positive surface of AgNPs. The AgNps as well as BIsH ligand showed high antimicrobial and bactericidal activity.

Raman Spectroscopic Characterization of Photonanocatalyst Aided Alkaline Pretreated Corn Stover Biomass

The most expensive and principal step in the process of converting cellulosic biomass into biorenewables and biofuel is the pretreatment during which lignin and cellulose crystalline structure is broken down. In this study, TiO2 nanoparticles were utilized as photocatalyst in addition to alkaline (ammonia and sodium hydrate) treatment of corn stover biomass to improve delignification ability and reduce the energy and chemical loadings to make the process more environmentally friendly. Raman Spectroscopic imaging, as an accurate and rapid chemical characterization method, was utilized to investigate the molecular compositional and structural changes occurring during the pretreatment process in the corn stover biomass qualitatively. Lignin characteristic peaks at 1,600, 1,620 and 1,690 cm-1 as well as cellulose characteristic peaks at 1,059 and 2,888 cm-1 were identified through Raman Spectroscopic measurement as indicators of the effects of the pretreatment. Real-time quantitative analysis of these functional peaks revealed the molecular structural changes during delignification, potentially may lead to optimization of the processing parameters to reduce the processing cost in the future.

Nanostructured morphology control and optical properties of ZnO thin film deposited from chemical solution

Zinc oxide thin films with the sheet-like, rose-like to flower-like structures were directly synthesized on glass substrates through a simple, rapid, facile and one-step chemical bath deposition method at 80°C. The formation mechanisms of these ZnO structures were proposed. It was revealed that the morphologies were controlled by anisotropic structure of ZnO and the contents of TSC and NH4OH. Particularly, the content of NH4OH played an important role in controlling the morphology of ZnO thin film. Moreover, optical properties of ZnO thin films with three morphologies were also investigated by the UV–vis transmittance spectra and photoluminescence spectra.

PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈111〉 and 〈200〉 directions while being limited in the 〈011〉 direction.