Simple Chemical Precipitation Research Articles

A comparison investigation on photocatalytic activity performance and adsorption efficiency for the removal of cationic dye: Quantum dots vs. magnetic nanoparticles

In this research, the efficiencies of two methods, including quantum dots (QDs) based photocatalysis and magnetic nanoparticles (MNPs) based adsorption for the decolorization of Victoria blue R (VBR) were investigated and compared, experimentally. Synthesis of functionalized zinc sulfide (ZnS) QDs and iron oxide (Fe3O4) MNPs was carried out by a simple chemical precipitation method. 2-mercaptoethanol (ME) and sodium dodecyl sulfate (SDS) were applied for capping and surface modification of ZnS QDs and Fe3O4 MNPs, respectively. The prepared nanoparticles have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM). The mean particle size of ZnS QDs and Fe3O4 MNPs were approximated to be 1–3nm and 50–80nm, respectively. In the photocatalytic and adsorption investigations, influence of affecting parameters on the removal efficiencies was studied and optimized. According to the results, both methods can be considered as green, simple and efficient strategies for the removal of organic dyes. However, comparative investigation of the characteristics of the methods demonstrated that the efficiency of the QDs based photodegradation method for the removal of VBR is higher than MNPs based adsorption process. It was also found that the maximum decolorization of 95% and 65% can be achieved after 20 and 45min at optimum pH 10, 7.5, in the presence of 8 and 10mg of QDs and MNPs for 30mg/L of VBR, respectively. Finally, isotherm adsorption model and photodegradation mechanism were discussed, too.

Enhanced Adsorption of Hexavalent Chromium onto Magnetic Calcium Ferrite Nanoparticles: Kinetic, Isotherm, and Neural Network Modeling

Calcium ferrite nanoparticles with super-paramagnetic behavior were synthesized via simple chemical precipitation method for effective removal of hexavalent chromium from aqueous media. The properties of synthesized nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM) measurements. The ferrite nanoparticles have shown polycrystalline nature and high BET specific surface area (229.83 m2/g) with active functional groups on the surface. The adsorption process follows second-order kinetics with the involvement of intra-particle diffusion and adsorption capacity as much as 124.11 mg/g was determined from the Langmuir isotherm. The thermodynamic analysis revealed that the adsorption process was feasible, spontaneous, and exothermic in nature. A three-layer feed-forward back-propagation artificial neural network (ANN) model was employed to predict the removal (%) of Cr(VI) ions as output. Optimal ANN network (4:8:1) shows the minimum mean squared error (MSE) of 0.00161 and maximum coefficient of determination (R2) of 0.984. The adsorption process is mostly influenced by solution pH and followed by adsorbent dosage, initial Cr(VI) concentration, and contact time as illustrated by sensitivity analysis. With small size and high surface area, biocompatibility, ecofriendly nature, easy magnetic separation, and enhanced adsorption capacity towards Cr(VI), calcium ferrite nanoparticles will find its potential application in wastewater remediation.

L-lysine monohydrate mediated facile and environment friendly synthesis of SnO2 nanoparticles and their prospective applications as a catalyst for the reduction and photodegradation of aromatic compounds

Herein, we present the preparation of SnO2 nanoparticles successfully by simple chemical precipitation method employing amino acid, l-lysine monohydrate. The prepared nanoparticles were characterized in detail using different technique, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transformed infrared spectroscopy (FT-IR) for morphological and structural analysis. The optical properties were studied using UV–vis spectroscopy. The characterization results revealed that the synthesized SnO2 nanoparticles possess tetragonal rutile crystalline structure. The size of the SnO2 nanoparticles was found to be increased (∼4–17nm) with increase in annealing temperature. The band gap energy was found to be increased from 3.8eV to 4.1eV with increase in size of the SnO2 nanoparticles. The synthesised SnO2 nanoparticles showed an invincible photocatalytic property in the degradation of malachite green oxalate dye and Victoria blue dye from aqueous phase under direct sunlight within 120min. Both the dyes followed pseudo first order reaction and the rate of the constant (k) of photodegradation of malachite green oxalate dye and Victoria blue was found to be 1.6×10−2min−1 and 1.06×10−2min−1, respectively. The SnO2 nanoparticles was also found to have outstanding catalytic activity for the reduction of 4-nitrophenol into 4-aminophenol in aqueous medium. The complete reduction took place within 27min. The kinetic of the reduction was found to be pseudo first order with a rate constant (k) 9.3×10−4s−1.

Hierarchically Layered MoS2/Mn3O4 Hybrid Architectures for Electrochemical Supercapacitors with Enhanced Performance

We for the first time report a novel kind of supercapacitor using hierarchical MoS2/Mn3O4 hybrid architectures as electrodes based on layered MoS2 and Mn3O4 nanoparticles via a simple and low-cost hydrothermal and chemical precipitation route. The Mn3O4 nanoparticles are homogeneously incorporated into thin layers of MoS2 hierarchical architectures. The cycle stability of MoS2/Mn3O4 nanostructure is greatly improved, still reserves a capacity of 119.3Fg−1 after 2000 cycles at a current density of 1.0Ag−1, about 69.3% reservation of the initial capacitance, more than two times higher than that of pure layered MoS2 electrode. The good performance is due to the synergistic effect between the layered MoS2 and Mn3O4 nanoparticles. The layered hybrid displays a larger specific surface to provide enough active sites for the redox reaction and shorten the distance of charge transfer for ions and electrons. While Mn3O4 acts as a holder to enhance the stability of the MoS2 framework and provides additional capacity. The Mn3O4 nanoparticles can serve as a holder and prevent MoS2 nanosheets from restacking. Moreover, the MoS2 sheets act as subtracts to improve to the conductivity of Mn3O4. The layered MoS2/Mn3O4 hybrid inspires a new way of designing high-performance electrochemical supercapacitors.

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.

Mesoporous cobalt hydroxide prepared using liquid crystal template for efficient oxygen evolution in alkaline media

Active, stable and economical electro-catalysts are very necessary for hydrogen production through water splitting by electrolysis. This work reports the synthesis and characterization of highly porous cobalt hydroxide (meso-Co-OH) formed by a simple chemical precipitation within the interstitial space of liquid crystal template. The physicochemical properties of the meso-Co-OH were characterized by surface area analyzer, X-ray diffraction, XPS, scanning and transmission electron microscopes. The meso-Co-OH exhibits low crystallinity and high surface area of 457±5m2/g with a mesoporous structure and pore diameter of 4.0±1.0nm. As confirmed by the electrochemical characterizations, the meso-Co-OH is highly effective electro-catalyst for oxygen evolution reaction (OER) at low applied potential and shows superior activity and stability than iridium oxide during long term water electrolysis in alkaline media. The meso-Co-OH shows oxygen evolution current and onset potential comparable to the IrO2 catalyst and the current is enhanced by 10 times than the values of bulk cobalt hydroxide electrode. For meso-Co-OH catalyst the oxygen evolution overpotential of 1.55V (vs. RHE) at current density of 25mA cm2 has been achieved in 1.0M KOH. The enhanced OER activity was attributed to the substantial increase in the active catalyst surface area due to the formation of mesoporous network within the cobalt hydroxide framework.

Synthesis and characterization of mixed phase manganese ferrite and hausmannite magnetic nanoparticle as potential adsorbent for methyl orange from aqueous media: Artificial neural network modeling

In this study, a novel magnetic nanoscale adsorbent of mixed phase manganese ferrite and hausmannite (MNF–HM) was synthesized by a simple chemical precipitation method and its adsorptive property towards a toxic anionic dye methyl orange (MO) was investigated. This new adsorbent was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), point of zero charge (PZC), vibrating sample magnetometer (VSM) measurements and Brunauer–Emmett–Teller (BET) analysis. These crystalline mixed phase MNF–HM nanoparticles show high saturation magnetization (30.12emu/g) as well as high specific surface area (100.62m2/g) and pore volume, which makes it a magnetically separable efficient adsorbent with maximum adsorption capacity of 303.66mg/g for MO at room temperature. The solution pH becomes the most influencing parameter and maximum adsorption efficiency of 97.4% is observed within 45min at solution pH2.0 with initial MO concentration of 50mg/L and MNF–HM nanoparticle dose of 1.0g/L. An artificial neural network (ANN) model was developed for accurate prediction of MO removal (%) and optimal ANN structure (4–7–1) shows minimum mean squared error (MSE) of 0.00071 and high determination coefficient (R2) of 0.990. Isotherm modeling exhibited that Langmuir isotherm model is the most efficient one in explaining its adsorption behavior and the kinetic studies reveal that the adsorption process follows pseudo-second-order kinetic model with the involvement of intra-particle diffusion. Thermodynamic studies reveal that the adsorption process is feasible, spontaneous and exothermic in nature.

Photocatalytic activity of enlarged microrods of α-Bi2O3 produced using ethylenediamine-solvent

Microrods of α-Bi2O3 were prepared by a simple chemical precipitation method, replacing the hydroxyl (OH−) ions by the ethylenediamine-solvent as both a precipitating and capping agent; it can also function as a morphological template. The influence of the ethylenediamine solvent concentration on the crystalline structure, optical properties, morphology, and photocatalytic activity was investigated. The prepared samples were characterized by X-ray diffraction, diffuse reflectance spectroscopy, scanning electron microscopy, Fourier transformed IR analysis, thermal analysis and photoluminescence spectroscopy. The adsorption capacity in dark conditions and the photocatalytic activity under UV-light were studied as a function of the photocatalyst load by using indigo carmine dye solution. The highest photoactivity was observed for the non-agglomerated Bi2O3 microrods obtained with ethylenediamine-solvent at 40vol%. The photocatalytic mechanism was discussed as a function of surface oxygen vacancies generated along to the microrod surface caused by the ethylenediamine-solvent.

Synthesis and magnetic investigation of cobalt ferrite nanoparticles prepared via a simple chemical precipitation method

In this research cobalt ferrite (CoFe2O4) nano-crystalline powders were prepared by simple chemical precipitation method using cobalt sulfate. The CoFe2O4 nanoparticles were characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infra-red spectroscopy. The crystallite size of CoFe2O4 nanoparticles was calculated by Debye–Scherrer formula. The effect of precursor, capping agent, temperature and concentration on the morphology and particle size of the products was investigated. Starch and gelatin as green, safe, water-soluble and cost-effective capping agents were used. Alternative gradient field magnetometer confirms dominant influence of temperature on the morphology and magnetic domains. Results approve magnetic samples exhibit either ferromagnetic or super-paramagnetic behavior.

α-MnO2 Nanoparticles with High Surface Area for Electrochemical Supercapacitor Application

The large scale energy production and developments in renewable energy sources requires efficient energy storage systems. The physical and chemical charge storage techniques along with high power and energy density brought electrochemical supercapacitors (ECs) as a versatile power source. The high rates of charging and discharging with long cycle life as well as the economical and eco-friendly nature support ECs to various energy applications. Since the last couple of decades, Supercapacitors with various metal oxides as electrode materials got a great interest among researchers. Here we synthesised α-MnO2 nanoparticles by simple chemical precipitation method and are subjected to heat treatment at 300 ˚C, 500 ˚C and 700 ˚C. The structural formation of as- prepared and annealed MnO2 are confirmed by XRD analysis. The functional group and optical absorption studies are done by Fourier transform infrared spectroscopy (FTIR) and UV visible spectroscopy. The surface area of the samples is measured using Brunauer-Emmett-Teller (BET) method. Finally electrochemical properties are evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge techniques. The cyclic voltammogram and charge-discharge curve recorded indicates MnO2 nanoparticles annealed at 300 ˚C for 5 h shows better electrochemical behaviour.

Simple synthesis of novel phosphate electrode materials with unique microstructure and enhanced supercapacitive properties

Flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O have been successfully synthesized by a simple chemical precipitation method. X-ray diffraction (XRD) patterns reveal an amorphous phase formation of nickel phosphate (Ni3P2O8) and pure monoclinic phase of Fe3P2O8·8H2O. The novel flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O when used for supercapacitor electrode materials exhibit a high specific capacitance (Cm) of 1464F/g and 200F/g at a current density of 0.5A/g, respectively. Eventually, an asymmetric supercapacitor is fabricated using Ni3P2O8 as positive electrode and Fe3P2O8·8H2O as negative electrode. A high specific capacitance of 94F/g is achieved in the high-voltage region of 0 ∼1.6V, and a large energy density of 32.6Wh/kg is delivered at power density of 420W/kg. The findings demonstrate the important and great potential of developing metal phosphate based materials for supercapacitors.

A Simple Chemical Precipitation Method of Titanium Dioxide Nanoparticles Using Polyvinyl Pyrrolidone as a Capping Agent and Their Characterization

A Simple Chemical Precipitation Method of Titanium Dioxide Nanoparticles Using Polyvinyl Pyrrolidone as a Capping Agent and Their Characterization

Enhanced photodegradation activity of methyl orange over Ag2CrO4/SnS2 composites under visible light irradiation

Novel Ag2CrO4/SnS2 composites were prepared by a simple chemical precipitation method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The visible light photocatalytic tests showed that the Ag2CrO4/SnS2 composites enhanced photocatalytic activities for the photodegradation of methyl orange (MO) under visible light irradiation (λ>420nm), and the optimum rate constant of Ag2CrO4/SnS2 at a weight content of 1.0% Ag2CrO4 for the degradation of MO was 2.2 and 1.5 times larger than that of pure Ag2CrO4 and SnS2, respectively. The improved activity could be attributed to high separation efficiency of photogenerated electrons-hole pairs on the interface of Ag2CrO4 and SnS2, which arised from the synergistic effect between Ag2CrO4 and SnS2. Moreover, the possible photocatalytic mechanism with superoxide radical anions and holes species as the main reactive species in photocatalysis process was proposed on the basis of experimental results.

An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO) and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.

Fe3O4 and MnO2 assembled on halloysite nanotubes: A highly efficient solid-phase extractant for electrochemical detection of mercury(II) ions

In this study, a novel and simple magnetic electrochemical sensing protocol for the sensitive detection of Hg(II) in aqueous media was demonstrated. For this purpose, the halloysite nanotubes-iron oxide–manganese oxide nanocomposite (HNTs-Fe3O4–MnO2) was successfully synthesized for the first time. The synthesis process involves the deposition of Fe3O4 nanoparticles on the surface of HNTs using a simple chemical precipitation method, subsequent formation of wire-like MnO2 nanoparticles on the surface of HNTs-Fe3O4 composites by hydrothermal method with potassium permanganate (KMnO4) and ammonium persulfate ((NH4)2S2O8). The resulting HNTs-Fe3O4–MnO2 nanocomposite was suspended in mercury solution and then brought on the surface of a magnetic carbon paste electrode (MCPE). The amount of analyte was detected electrochemically by applying differential pulse voltammetry (DPV). The conditions of extraction and voltammetric determination were studied and optimized. The proposed method exhibited a linear relationship towards Hg(II) concentrations ranging from 0.5 to 150μgL−1. The detection limit achieved was 0.2μgL−1 (3Sb/m), which is lower than the US Environmental Protection Agency (EPA) standard (2μgL−1 for drinkable water). The proposed methodology was applied for quantification of Hg(II) in real water samples and good recoveries were obtained from 96.0 to 102.7%.

Twist fibrous structure of CS–SnO2–PANI ternary hybrid composite for electrochemical capacitance performance

In this study, a twisted fibrous CS–SnO2–PANI ternary hybrid composite structure was synthesized via a two step method; the CS–SnO2 hybrid composite was prepared by a simple chemical precipitation method and the resulting CS–SnO2 suspension was coated with PANI by in situ chemical oxidative polymerization of aniline monomer in acidic medium using ammonium persulphate as the oxidant.

Modification of Structural and Vibrational Properties of ZnO Nanoparticles Prepared by Simple Chemical Precipitation Method

In this work, zinc oxide (ZnO) nanoparticles were synthesized by simple chemical precipitation method in the present of zinc nitrate as zinc precursor and sodium hydroxide as hydroxide precursor. The vitamin C was used as modifier media to modify the structural properties of ZnO nanoparticles. The microstructures of ZnO nanoparticles were characterized by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Selected area electron diffraction (SAED) patterns showed that polycrystalline hexagonal phase of ZnO. The defects and impurity contents in nanoparticles were investigated by Fourier transform infrared (FT-IR) spectroscopy. The results show few carboxylate and hydroxyl impurities for larger particles when addition modifier increases. Surface areas of nanoparticles were measured by Brunauer Emmett Teller (BET) method. In addition, the results exhibited the dramatically change in structural properties of ZnO nanoparticles due to the effect of vitamin C.

Study of structural, morphological, optical and electroluminescent properties of undoped ZnO nanorods grown by a simple chemical precipitation

AbstractIn this work, zinc oxide (ZnO) nanorods were obtained by a simple chemical precipitation method in the presence of capping agent: polyvinyl pyrrolidone (PVP) at room temperature. X-ray diffraction (XRD) result indicates that the synthesized undoped ZnO nanorods have hexagonal wurtzite structure without any impurities. It has been observed that the growth direction of the prepared ZnO nanorods is [1 0 1]. XRD analysis revealed that the nanorods have the crystallite size of 49 nm. Crystallite size is calculated by Debye-Scherrer formula and lattice strain is calculated by Williomson-Hall equation. Cell volume, Lorentz factor, Lorentz polarization factor, bond length, texture coefficient, lattice constants and dislocation density have also been studied. We also compared the interplanar spacings and relative peak intensities with their standard values at different angles. The scanning electron microscope (SEM) images confirmed the size and shape of these nanorods. It has been found that the diameter of the nanorods ranges from 1.52 μm to 1.61 μm and the length is about 4.89 μm. It has also been observed that at room temperature ultraviolet visible (UV-Vis) absorption band is around 355 nm (blue shifted as compared to the bulk). The average particle size has also been calculated by mathematical model of effective mass approximation equation, using UV-Vis absorption peak. Finally, the bandgap has been calculated using UV-absorption peak. Electroluminescence (EL) studies show that emission of light is possible at very small threshold voltage and it increases rapidly with increasing applied voltage. It is seen that smaller ZnO nanoparticles give higher electroluminescence brightness starting at lower threshold voltage. The brightness is also affected by increasing the frequency of AC signal.

Effect of oxide nanoparticles on structural properties of multiwalled carbon nanotubes

A simple chemical precipitation route is reported to partially decorate mutliwalled carbon nanotubes (MWCNTs) with oxide nanoparticles in the present study. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to investigate the structural properties of MWCNTs composite with nickel, cuprous, zinc and tin oxides nanoparticles. Raman analysis confirms that, ZnO nanoparticles attached nanotubes show more ordering of graphene layers as compared to the others because of uniform dispersion of nanoparticles. It is investigated that, adopted route proved helpful to improve the structural properties of the nanotubes.

SYNTHESIS AND CHARACTERIZATION OF PURE ZINC OXIDE NANOPARTICLES AND NICKEL DOPED ZINC OXIDE NANOPARTICLES

In this paper, Zinc oxide nanoparticles are synthesized by simple wet chemical precipitation method. Zinc nitrate and sodium hydroxide are used as the starting materials.Zinc oxide nanoparticles are formed at a very low temperature of the order of 80 0 C. Nickel doped zinc oxide nanoparticles are synthesized in two steps. In first step precipitate is obtained by reduction of mixture of zinc nitrate, ferric nitrate and starch by sodium hydroxide solution while in second step the given precipitate is thermally decomposed at high temperature of the order of 400 0 C. The crystallinity of the synthesized nanoparticles is then confirmed by X ray diffraction spectroscopy (XRD).The elemental composition of the powder is detected by Energy Dispersive X ray spectroscopy (EDAX). The morphology of the powder is investigated by Scanning Electron Microscopy (SEM). Magnetic characterization of nickel doped zinc oxide nanoparticles is done by Squid Magnetometer. Low temperature magnetization behavior revealed ferromagnetic behavior of sample.