Trisodium Citrate Concentration Research Articles

Effect of Trisodium Citrate Concentration on the Structural and Photodiode Performance of CdO Thin Films

CdO thin films were deposited on glass and silicon substrates by simple perfume atomizer at 350°C using cadmium acetate and trisodium citrate (TSC). The effect of the TSC concentration on the structural, morphological, optical, and photoconductive properties of the prepared CdO thin films was investigated. X-Ray diffraction (XRD) studies of the deposited films revealed improvement in crystalline nature with increase of TSC concentration. Films prepared without TSC showed porous nature, not fully covering the substrate, whereas films prepared using TSC exhibited full coverage of the substrate with uniform particles. Optical transmittance study of the films showed high transmittance (50% to 60%), and the absorption edge was found to shift towards the red region depending on the TSC concentration. The films exhibited a direct band-to-band transition with bandgap varying between 2.31 eV and 2.12 eV. Photoconductivity studies of the n-CdO/p-Si structure for various TSC concentrations were also carried out. I–V characteristics of this n-CdO/p-Si structure revealed the formation of rectifying junctions, and its photoconductivity was found to increase with the TSC concentration.

Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties

Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity.

SYNTHESIS OF SILVER NANOPARTICLES BY CHEMICAL REDUCTION METHOD: EFFECT OF REDUCING AGENT AND SURFACTANT CONCENTRATION

Uniform, well-dispersed, silver nanoparticles (AgNPs) were prepared by a simple chemical reduction method. The particles were synthesized via the reduction of AgNO3 by trisodium citrate and ascorbic acid as a surfactant. The resulting AgNPs were characterized by X-ray diffraction analysis, transmission electron microscopy, and scanning electron microscopy. It was found that the size of the AgNPs ranged from 35– 80 nm, with an average of 50 nm. In this study, the effects of trisodium citrate and ascorbic acid, which act as reducing agent and surfactant respectively on the morphology of the silver nanoparticles, were investigated. It was found that the increasing concentration of trisodium citrate resulted in decreasing size of silver nanoparticles, while increasing the concentration of ascorbic acid shows the opposite effect. Moreover, the quasi-spherical shape of as-synthesized silver nanoparticles is also more uniform with the increase of trisodium citrate. Meanwhile, a slight change in particle shape from quasi-spherical to polygonal was observed as the concentrations of ascorbic acid were increased. Keywords: Chemical synthesis; silver nanoparticles; reducing agent; surfactant.

Size tunable gold nanoparticle and its characterization for labeling application in animal health

Aim: The aim of the present study was to synthesize different sizes of gold nanoparticles (GNPs) and their characterization for use as a label in lateral flow assay particular for the detection of bluetongue in small ruminants. Materials and Methods: Size controlled synthesis of GNPs was done by using different concentration of sodium citrate. In this study, five different types of GNP were synthesized by using trisodium citrate (Na 3 C 6 H 5 O 7 2H 2 O) that reduces 20 mM concentration of gold solution (HAuCl 4 ). These different types of GNPs were characterized in terms of morphology, size, shape and λ max by transmission electron microscopy and ultraviolet-visible spectroscopy respectively. Results: In the present work, it was found that the size of GNP mainly depends upon the concentration of sodium citrate. By use of 0.09375%, 0.1875%, 0.375%, 0.75% and 1.5% of sodium citrate solution, GNPs were synthesized. In our study, the size of GNP was found ranging from 25 nm to 230 nm. The size was found large with less concentration of sodium citrate (i.e. with 0.09735%) and small with large concentration of sodium citrate (1.5%) and λ max was found to be 450-530 nm in all size of GNP. Conclusions: The size of GNPs is mainly dependant on the concentration of trisodium citrate, gold salt concentration, optimum pH and temperature. The GNP synthesized by this method has been used as a label for the development of lateral flow assay against diagnosis of bluetongue disease in small ruminant.

Photocatalytic H₂ Production Using Pt-TiO₂ in the Presence of Oxalic Acid: Influence of the Noble Metal Size and the Carrier Gas Flow Rate.

The primary objective of the experiments was to investigate the differences in the photocatalytic performance when commercially available Aeroxide P25 TiO2 photocatalyst was deposited with differently sized Pt nanoparticles with identical platinum content (1 wt%). The noble metal deposition onto the TiO2 surface was achieved by in situ chemical reduction (CRIS) or by mixing chemically reduced Pt nanoparticle containing sols to the aqueous suspensions of the photocatalysts (sol-impregnated samples, CRSIM). Fine and low-scale control of the size of resulting Pt nanoparticles was obtained through variation of the trisodium citrate concentration during the syntheses. The reducing reagent was NaBH4. Photocatalytic activity of the samples and the reaction mechanism were examined during UV irradiation (λmax = 365 nm) in the presence of oxalic acid (50 mM) as a sacrificial hole scavenger component. The H2 evolution rates proved to be strongly dependent on the Pt particle size, as well as the irradiation time. A significant change of H2 formation rate during the oxalic acid transformation was observed which is unusual. It is probably regulated both by the decomposition rate of accumulated oxalic acid and the H+/H2 redox potential on the surface of the catalyst. The later potential is influenced by the concentration of the dissolved H2 gas in the reaction mixture.

Effect of tri-sodium citrate concentration on structural, optical and electrical properties of chemically deposited tin sulfide films

Tin sulfide thin films were deposited onto glass substrates by chemical bath deposition. The effects of molar concentration of the complexing agent, tri-sodium citrate, on the structural, morphological, optical and electrical properties of the films were investigated. The films are characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, optical absorption spectroscopy and Hall effect measurements. Polycrystalline film structure in orthorhombic phase was determined. Flower-like spherical grains are observed on the surface. While their average size increased from 345nm to 750nm when the tri-sodium citrate concentration was increased from 6.4×10−3M to 8.0×10−3M, the surface roughness varied in an opposite manner from approximately 120.18nm to 29.36nm. For these concentrations, optical band gap of the films decreased from 1.40eV to 1.17eV, whereas the Hall conductivity, mobility and carrier concentration of the films increased slightly from 5.91×10−5 to 8.78×10−5(Ωcm)−1, from 148 to 228cm2V−1s−1 and from 1.73×1012 to 3.59×1012cm−1, respectively.

Preparation of ZnO hollow spheres with different surface roughness and their enhanced gas sensing property

ZnO hollow spherical samples with different surface roughness have been synthesized using a one-step, template-free hydrothermal method. Materials characterization has included XRD, SEM, TEM, XPS and XRF. It was found that the surface roughness of the ZnO hollow spheres can be tuned from rough to smooth via regulating trisodium citrate concentration during the synthesis. When 2mM of trisodium citrate was used, ZnO hollow spheres showed the roughest surface morphology. With increasing the citrate concentration from 2 to 6mM, the resultant ZnO hollow sphere morphology became increasingly denser and smoother. When the citrate concentration was further increased to 8mM, however, the morphology became rough again. Sensors fabricated using the ZnO hollow spheres were characterized by the response to alcohol vapor. The roughest sample gave the best sensor response toward 10–500ppm alcohol vapor, about 11–16 times higher than the reference one prepared without citrate. This corresponds to a remarkable sensor response as high as 402 and an extrapolated detection limit 0.5ppm. The reasons behind the improvements in sensor performance are discussed.

Gold nanoparticle: synthesis and characterization

Aim: The aim of present study was to synthesize and characterize gold nanoparticles applicable in therapeutics and diagnostics tool for different diseases in particular for peste des petits ruminants (PPR). +3 0 Materials and Methods: Gold nanoparticles were synthesized by the reduction of Au (HAuCl ) to Au . For this purpose, the 4 reduction reaction between tetrachloroauric acid (HAuCl ) and trisodium citrate (Na C H O .2H O) was used in an aqueous 4 3 6 5 7 2 solution. The initial gold concentration, trisodium citrate concentration and temperature were changed and their effects on particle size and size distribution were observed. At the end of the reduction reaction, gold nanoparticles with narrow size distribution were obtained. Zeta sizer and transmission electron microscopy (TEM) were used to characterize and determine the size and size distribution of the synthesized gold nanoparticles. Results: In the present work optimal gold salt concentration, trisodium citrate concentration and temperature were found to be 0 20 mM, 1.5% and 97 C respectively. The morphology, size, and shape of synthesized gold nanoparticles were characterized by using spectrophotometry, transmission electron microscopy (TEM) and zeta sizer. In our study colloidal gold nanoparticle of 15-20 nm size were obtained. Conclusions: The uniform gold nanoparticles were synthesized by the citrate reduction method. The effects of various experimental parameters (Gold salt concentration, trisodium citrate concentration and mixing rate) on its size and size distribution at optimum pH and temperature were investigated. The gold nanoparticle synthesized by this method has been used for the preparation of gold-labeled lateral flow strip for peste des petits ruminants (PPR) diagnosis.

Morphology control and temporal growth of a continuous silver shell on core–shell spheres

We report the synthesis of Fe@TiO2@Ag core–shell-structured spheres with an extremely continuous and complete Ag shell (at least 50 nm in thickness). In particular, we investigated the Ag shell growth on the Fe@TiO2 spheres using an electroless deposition technique based on electrostatic attraction. In order to induce a well-defined Ag shell surface, we controlled various synthesis variables and found that the concentration of trisodium citrate, the molar ratio of NaOH/AgNO3, and the aging time of ammoniacal Ag solution all played a critical role in the formation and growth of the Ag shell. We investigated, for the first time, the temporal growth of the Ag shell at the early stage of the Ag growth reaction to examine how Ag islands grow and coalesce when trisodium citrate is used. In addition, we also investigated the reflectance of the resultant particles to evaluate the degree of continuity of the Ag shell.

Hydrothermally controlled ZnO nanosheet self-assembled hollow spheres/hierarchical aggregates and their photocatalytic activities

We synthesized ZnO nano-micro structures, including microrods, nanosheets, a nanosheet self-assembled hollow sphere (NSHS), and a hollow hierarchical aggregate (HHA) by changing the concentration of trisodium citrate in a hydrothermal process. The NSHS was formed by the self-assembly of 2D nanosheets on the surface of a formaldehyde bubble, while the HHA was obtained by the self-assembly and hierarchical arrangement of NSHS. The photocatalytic activities of the ZnO structures were evaluated from the degradation of methylene blue under visible and black light irradiation. The NSHS showed better photocatalytic performance due to its excellent photon absorbance, low defect density and low emission quantum yield compared with the HHA. Furthermore, the size and number of the 2D nanosheets hydrothermally grown on the NSHS bubble template were controlled by changing the growth temperature.

Copper-Molybdenum Source Ratio and Complexing Agent for High Molybdenum Content in Electrodeposited Cu-Mo

Cu-Mo composites have been one of candidates for material of heat-sinks in electronic devices. We obtained Cu-Mo composites by electrodeposition using CuSO4 and Na2MoO4 with trisodium citrate as complexing agent. The presence of molybdenum in Cu-Mo was demonstrated by X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy. The molybdenum content in Cu-Mo composites depended on the concentration ratio of Na2MoO4/(Na2MoO4 + CuSO4) in the electrolyte, kinds and concentration of complexing agents. The mol ratio of Na2MoO4/(Na2MoO4 + CuSO4), from 0.75 to 0.87 provided larger molybdenum content at 0.05 A/dm2 of electrodeposition current. The molybdenum content increased with decreasing current density during electrodeposition in the range of 0.05–0.3 A/dm2. Trisodium citrate was the most effective complexing agent among trisodium citrate, glycolic acid, EDTA (4Na) and combinations of them for increasing molybdenum content. The molybdenum content reached up to 22.9 wt% at 0.396 mol/dm3 of trisodium citrate concentration. X-ray diffraction shows that no peaks related to molybdenum was observed, moreover, the intensity and the width of Cu(111) peaks decreased and enlarged with increasing molybdenum content. These indicate that the structure of molybdenum in copper-molybdenum composites was amorphous, furthermore, higher molybdenum content made copper structure close to amorphous.

Studies on the Controlling of the Microstructural and Morphological Properties of Al Doped ZnO Thin Films Prepared by Hydrothermal Method

Al doped ZnO (AZO) thin films were prepared on ZnO coated glass substrates by hydrothermal synthesis technique using aqueous solutions containing zinc nitrate hexahydrate, ammonium hydroxide, and different sodium citrate concentrations at 60 °C for 6 h. The effects of different trisodium citrate concentrations on the microstructural, crystallinity, morphological, optical, and chemical properties of thin films were investigated. X-ray diffraction studies showed that the AZO thin films were grown as a polycrystalline wurtzite hexagonal phase with a c-axis preferred orientation and without an unwanted second phase regardless of trisodium citrate concentrations. The thickness and grain sizes of AZO thin films decreased with increasing trisodium citrate concentration. The microstructure of AZO thin films was changed from flat to needle shaped and the morphology was smoother with increasing trisodium citrate concentrations. The AZO thin films have a high transmittance in the visible region ranging from 75 to 85% and a sharp edge from 366 to 374 nm.

Concentration of trisodium citrate by electrodialysis

In this work, the experimental procedure and mathematical model formerly developed was used to describe the electrodialytic (ED) recovery of trisodium citrate. By performing several voltage–current, electro-osmosis and desalination tests, the main engineering parameters (i.e., the ion transport numbers in solution and membranes, effective solute and water transport numbers, effective surface area and resistances of membranes, and limiting electric current) of the ED process under study were assessed.As expected, the electric resistance of the cationic membranes (Rc) resulted to be about constant (0.11±0.02Ω) and independent of solute concentration, while that of the anionic ones (Ra) was not only greater than Rc, but also dependent on both the current applied and solute concentration. Moreover, in the ohmic region of the current–voltage curves Ra appeared to be a logarithmic function of the solution electric conductivity in the dilute compartment. On condition that the current applied was less than 2/3 of the limiting current for the cationic membrane (Ilim,c) the time course of the voltage applied to the ED stack when operating at a constant current of 0.75 or 1.5A was adequately predicted with a mean percentage error of ~20%.

Effect of trisodium citrate concentration on the particle growth of ZnS nanoparticles

ZnS nanoparticles were prepared by simple wet chemical precipitation method to study the effect of sulfur and trisodium citrate concentration on the particle growth of ZnS nanoparticles. Particle sizes were seen varied with the concentration of the sulfur and trisodium citrate. Compressive strain was observed only for a particular concentration of sulfur, and that sample was chosen for trisodium citrate experiments. Interestingly, the compressive strain was seen varied with the concentration of trisodium citrate and seen maximum for 2 M concentration of trisodium citrate. Further, interband transition was observed in the case of smaller crystallites prepared in the trisodium citrate. It is clearly observed from the FTIR analysis that the trisodium citrate acts as a stabilizer and capped the particles from further growth.

Effect of polyvinyl alcohol concentration on the ZnS nanoparticles and wet chemical synthesis of wurtzite ZnS nanoparticles

ZnS is one of the most important semiconducting materials, and this paper discusses the wet chemical synthesis of ZnS nanoparticles in cubic and hexagonal structures. The effect of polyvinyl alcohol concentration on the ZnS particle formation is studied, and ZnS nanocrystals smaller than the Bohr exciton radius have been prepared using the capping agent polyvinyl alcohol. ZnS nanocrystals of about 1.54 nm have been prepared, and their optical absorption shows interband transitions. It is found that the polyvinyl alcohol concentration has a tremendous effect on the particle growth, since particle sizes were varied with the concentration of polyvinyl alcohol. The important result is that the strain was seen negative due to the contraction of the particles. The important finding of this experiment is that the preparation of the hexagonal ZnS nanoparticles is possible at lower temperature when a particular concentration of trisodium citrate and polyvinyl alcohol is used simultaneously with the ZnS precursors.

Direct growth and shape control of Cu2O film via one-step chemical bath deposition

Direct deposition of cuprous oxide (Cu2O) film with different particle shapes has been achieved by a simple, one-step and inexpensive chemical bath deposition method with bargain glucose as reductant and trisodium citrate as complexant at low temperature (80°C). The influences of supersaturation determined by the reaction conditions including glucose, trisodium citrate and copper ion concentration on the number density and particle morphology of the Cu2O films have been investigated in detail. The particle morphology of the film was octahedral at low copper ion concentration with excessive glucose; with the increased copper ion concentration at excessive glucose, the spherical particles were obtained. The mechanism of morphology control has been approached on the basic theory of a diffusion-limited progressive growth model under different kinetic conditions as dictated by ion concentration.

Facile synthesis of alumina hollow microspheres via trisodium citrate-mediated hydrothermal process and their adsorption performances for p-nitrophenol from aqueous solutions

Alumina hollow microspheres with high adsorption affinity toward p-nitrophenol in water were prepared by using urea and trisodium citrate as precipitating and mediating agents, respectively, via a simple one-pot hydrothermal synthesis followed by calcination. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms measurement. This study shows that the morphology, specific surface area, and the pore structure of the resulting materials can be controlled by varying the concentration of trisodium citrate. The result of adsorption of p-nitrophenol onto the as-prepared samples revealed that the pseudo-second-order kinetic equation can better describe the adsorption kinetics. Furthermore, adsorption isotherm studies indicated that the resulting alumina microspheres are powerful adsorbents for the removal of p-nitrophenol from water with maximum adsorption capacity of 217.4mg/g.

Novel three-dimensional Co3O4 dendritic superstructures: hydrothermal synthesis, formation mechanism and magnetic properties

Well-defined porous Co3O4 nanodendrites have been synthesized by a simple one-pot hydrothermal method combined with subsequent calcination. Importantly, after thermal treatment, the dendritic morphology could be completely preserved. The as-obtained superstructures are characterized by several techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy, elemental analysis, transmission electron microscopy, high-resolution TEM and magnetometry. On the dendritic hierarchical structures, a number of nanorods with different lengths and widths are connected to the main trunk with a diameter of about 50 nm and length of several micrometers. Each branch is about 0.5–1.0 μm with a width ranging from 100 to 400 nm. The possible formation mechanism was proposed on the basis of the contrasting experiments. It demonstrated that trisodium citrate and acetone play important roles in the synthesis of Co3O4 nanodendrites, while the other reaction parameters, such as reaction temperature, concentration of trisodium citrate and reaction time, have close relationships with the final morphology of the Co3O4 products. Optical properties of Co3O4 nanodendrites were characterized by Raman and UV-vis spectroscopy. Magnetic property measurement shows that Co3O4 nanodendrites have a low Neel transition temperature of 35 K. The as-prepared mesoporous Co3O4 nanostructures are expected to have great applications in many fields.

Growth of ZnO hemispheres on silicon by a hydrothermal method

This paper reports a hydrothermal method to control the morphology of hemisphere ZnO nanostructures (NSs) fabricated on a Si substrate by using surfactant additive molecules. The shape of ZnO NSs was controlled by the concentration of the trisodium citrate (TSC) added during the main growth step. With increasing the TSC concentration from 0 to 1.3 and 2.6mM, the shape of ZnO NSs changed from a bundle of nanorods to a flower-like-shape composed of merged large hexagonal crystals, and finally to ZnO hemispheres. X-ray diffraction and photoluminescence spectroscopy revealed that the ZnO NSs had a wurtzite crystalline structure. The shape evolution mechanism of ZnO NSs could be explained using the surfactant-mediated growth model.

Development of a Silver Nanoparticle-Based Method for the Antioxidant Capacity Measurement of Polyphenols

A sensitive colorimetric method for the detection of polyphenols (i.e., flavonoids, simple phenolic, and hydroxycinnamic acids) was proposed in this research based on the reduction of Ag(+) ions by polyphenols in the presence of citrate-stabilized silver seeds. The color of the stable suspension was controlled by varying the concentration of trisodium citrate, silver nitrate, and silver seeds. The reduction of Ag(+) to spherical silver nanoparticles (SNPs) by polyphenols in the presence of trisodium citrate and silver seeds produced a very intense surface plasmon resonance (SPR) absorption band of SNPs at 423 nm. The plasmon absorbance of SNPs allows the quantitative spectrophotometric detection of the polyphenols, and the developed method gave a linear response over a wide concentration range of standard polyphenolic compounds. In contrast to other reported NP-based antioxidant assays, it was established in this work that growth but not nucleation of SNPs gave a linear concentration-dependent response. The trolox equivalent antioxidant capacity (TEAC) values of various (hydrophilic and lipophilic) antioxidants using the developed method were comparable to those of the CUPRAC assay. Common food ingredients like oxalate, citrate, fruit acids, amino acids, and reducing sugars did not interfere with the proposed sensing method. This assay was validated through linearity, additivity, precision and recovery, demonstrating that the assay is reliable and robust. The developed method was used to screen total antioxidant capacity (TAC) of some commercial fruit juices and herbal teas without preliminary treatment, and showed a promising potential for the preparation of antioxidant inventories of a wide range of food plants.