Sodium Citrate Concentration Research Articles

Degradation Kinetics of Fe-EDTA in Hydrogen Sulfide Removal Process

Available data on the degradation of Fe-EDTA liquid redox H2S removal processes are reviewed, and the effect of H2S molar flow rate, the initial concentration of Fe(III)EDTA, and the presence of sodium citrate in Fe-EDTA solution were investigated in this study. The semibatch with continuous flow of H2S containing biogas was used under a wide range of experimental conditions; , H2S molar flow rate, (1.08 × 10−3–3.40 × 10−3 mol/h), the initial concentration of Fe(III)EDTA, (2.17–8.16 mol/m3), and the concentration of sodium citrate, (0–300 mol/m3). The result showed that sodium citrate acted as stabilizer with a good ability to reduce the degradation rate. The degradation rate of Fe-EDTA was found to follow pseudo first-order kinetics. Empirical correlations expressed the degradation rate constant as a function of significant H2S molar flow rate, and the initial Fe(III)EDTA and sodium citrate concentration were successfully developed for the prediction of Fe-EDTA degradation rate. Moreover, the precipitated solid, called sulfur cake, was recovered, and its composition was investigated. The result revealed that the sulfur cake contained more than 98% sulfur element and almost balances with iron, and no significant EDTA was degraded into the solid form.

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

ObjectiveThe aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. Material and MethodsA total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. ResultsBrushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. ConclusionDespite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning.

Sodium citrate induces apoptosis in biocontrol yeast Cryptococcus laurentii

To provide the observation that sodium citrate induced apoptosis in biocontrol yeast Cryptococcus laurentii. The viability of the yeast cells was evaluated using the percentage of colony-forming units (CFU) of treated cells. The induction of cell death was dependent on the concentration of sodium citrate and exhibited typical apoptotic markers such as phosphatidylserine (PS) translocation as shown by annexin V coupled with fluorescein isothiocyanate (FITC) labelling and DNA fragmentation as detected by TdT-mediated dUTP-biotin nick end labelling (TUNEL) assay. The annexin V-positive cells reached the maximum (14·8%) on the third day, whereas TUNEL-positive cells increased gradually from 5·92 to 27·9% within 5 days of incubation in sodium citrate. In addition, confocal laser microscopy and flow cytometric analysis revealed that the induction of apoptosis was associated with the production of reactive oxygen species (ROS) that reached the highest intracellular level in the first day, before the peak of the early event (PS exposure) in apoptosis. The apoptosis was delayed by the addition of antioxidant glutathione (GSH), suggesting that ROS generated in this process plays a key role in the regulation of the apoptosis in C. laurentii cells. This study indicated that the apoptotic signals in C. laurentii are dependent on citrate ions and/or sodium ions, the concentration and initial acidity of sodium citrate. Induction of ROS in response to sodium citrate plays a significant role in apoptosis. Yeast Cryptococcus laurentii has been selected as an effective biocontrol indicator for the postharvest diseases because of its competition for nutrients and space with the pathogen in the wound of fruits. This study presents a convenient method for commercial production of yeast as biocontrol agent.

Effects of Sodium Citrate on MAO Process and Characteristics of Coatings Fabricated on AZ91D Magnesium Alloy

Microarc oxidation (MAO) coatings were prepared on AZ91D magnesium alloy in a novel dual electrolyte containing various concentrations of sodium citrate (C6H5Na3O7). The surface and cross-sectional morphologies, coating thickness and surface roughness were characterized by scanning electron microscopy (SEM), layer thickness meter and digital microscope, respectively. The corrosion resistance of coatings was evaluated by electrochemical impedance spectroscopy (EIS). The results showed that both the striking voltage and final voltage decreased gradually with the increase of C6H5Na3O7 concentration. When the C6H5Na3O7 concentration increased, surface roughness increased gradually, while thickness of the coating increased at first and then decreased. The coating formed in the electrolyte containing 5g/L C6H5Na3O7 had a much more uniform and compact microstructure with less micropores and micro-cracks. EIS test showed that the concentration of C6H5Na3O7 mainly affected the corrosion resistance of inner dense layer, and the coating with best corrosion resistance was obtained in the electrolyte containing 5g/L C6H5Na3O7.

CONTROLLING THE SIZE AND SIZE DISTRIBUTION OF GOLD NANOPARTICLES: A DESIGN OF EXPERIMENT STUDY

The Turkevich method is the oldest and most widely employed protocol for the production of colloidal gold. Gold nanoparticles are nontoxic in nature and have potential applications in various biomedical fields including drug delivery and bioimaging. These metallic nanoparticles can be functionalized with drugs, targeting ligands such as tumor necrosis factor and groups (e.g., Poly ethylene glycol) to provide shielding from undesired immune responses. In this study we investigate the influence of process variables on the synthesis of nanoparticles by the reduction of chloroauric acid ( HAuCl4 ) solution with sodium citrate. A design of experiment (DoE) approach was used to investigate the influence of production volume, temperature, stirring rate and sodium citrate concentration on the physical properties of the nanoparticles namely size, size distribution, zeta potential and UV-Vis characteristics. The study showed that the relative amount of sodium citrate added ( Au /citrate mole ratio) had a significant effect on the size, poly dispersity index (PDI), the number of peaks in the size distribution and the position of Lambda max in the UV-Vis spectra. By varying the Au /Citrate ratio it is possible to synthesize particles with average diameters from 20 to 80 nm. However, the use of low amounts of sodium citrate in order to produce particles larger than ~35 nm tends to result in a wide bimodal size distribution.

One-step reverse precipitation synthesis of water-dispersible superparamagnetic magnetite nanoparticles

Hydrophilic functionalization of nanoparticle surface is essential for their biomedical applications. Herein, we report a facile one-step reverse precipitation method to synthesize water-dispersible, biocompatible, and carboxylate-functionalized superparamagnetic magnetite (Fe3O4) nanoparticles with the help of biocompatible sodium citrate salt. Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential measurement, dynamic light scattering (DLS), and superconducting quantum interference device (SQUID) were used to characterize the as-prepared magnetite nanoparticles. The size of the as-prepared magnetite nanoparticles was tuned from 27 ± 3.8 to 4.8 ± 1.9 nm by changing the sodium citrate concentration from 25 to 125 mM. The sodium citrate concentration also influenced the water-dispersible stability of the as-prepared magnetite nanoparticles, which was due to the electrostatic repulsion.

Properties of ZnS Thin Films Prepared by CBD under Different Concentration of Complexing Agent

ZnS thin films were deposited on glass substrates using chemical bath deposition. The zinc sulfate and thiourea were used as precursors along with a stable complexing agent of sodium citrate in ammonia/ammonium chloride (pH=10.5) buffer solution. The ratio of Zn and complexing agent was changed from 6:1 to 1:1 by varying concentrations of the complexing agent. X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis spectrophotometer were used to investigate the structure, micrograph and optical characteristics of the ZnS thin films respectively. The concentration of sodium citrate has an effect on the crystalline size and crystallization. For the as-deposited thin films, the values of transmittances and Eg are about 85% and 3.8 eV respectively. However, they are decreased to 75% and 3.4 eV respectively after annealing. In addition, the concentration of the complexing agent has no remarkable influence on both the transmittance and the energy gap. The results show that the ZnS thin films with resistivity of 4.34×104 Ωcm are suitable for optoelectronic applications.

Preliminary Study on Preparation of Black Ceramic Coating Formed on Magnesium Alloy by Micro-arc Oxidation in Carbon Black Pigment-contained Electrolyte

Based on orthogonal design, black ceramic coating was obtained on AZ91D magnesium alloy with addition of carbon black pigment in electrolyte by micro-arc oxidation (MAO). The blackness, thickness, phase, morphology and composition of the coating were analyzed by visual detection, eddy current thickness meter, XRD, digital cameras and EDS. The reasonable preparation parameters were obtained, and the influences of current density, carbon ink concentration, Na2WO4 concentration, Na2SiO3 concentration and sodium citrate concentration on the blackness and thickness of the coating were studied. The results showed that adopting constant current mode, the ceramic coating with good color uniformity, blackness of 0.9 and thickness over 30μm could be prepared on AZ91D magnesium alloy surface by MAO under the conditions of current density 3A/dm2, carbon ink concentration 25mL/L, Na2WO4 concentration 1.5g/L, Na2SiO3 concentration 6g/L and sodium citrate concentration 0.3g/L. Carbon ink concentration and current density were the main effect factors of the coating blackness and thickness, respectively. Coating blackness rose significantly with the increasing of carbon ink concentration and coating thickness increased with the increasing of current density at first and then decreased. Coating blackness and thickness all increased with the increasing of Na2WO4 concentration. As Na2SiO3 concentration increased, coating blackness gradually decreased, and there was little change of coating thickness. Sodium citrate concentration has little influence on coating blackness, while coating thickness decreased as it increased.

Size and concentration controlled growth of porous gold nanofilm

AbstractAt an air/water interface, diffusion‐limited aggregation (DLA) of gold nanoparticles can form porous gold thin films. This porous film roughly consists of a network of irregular nanowires. For this air–water system, external parameters like temperature are well studied, while the influence of internal parameters, e.g., the size and concentration of the nanoparticles, have not been studied in detail. Here, we report on the growth of porous gold nanofilms for different nanoparticle sizes and concentrations to get a relationship between the morphology of the films and the internal parameters. The gold nanoparticles were synthesized by reducing HAuCl4 using sodium citrate. Transmission electron microscopy (TEM) characterization showed a linear relation between the formed gold nanowires and the concentration of HAuCl4 if the concentration of sodium citrate is unchanged. A linear dependency was also found between the wire diameter and the gold nanoparticle concentration, and between the wire diameter and volume fraction of the nanoparticles. The electrical resistance of the films was measured, showing a linear relation between resistance and the inverse of the cross‐sectional area of the nanowires. This study shows the relation between the morphology and resistance of the grown porous films and the controllable internal parameters that will be useful in further exploration of this thin‐film growth method.

The use of the Fourier Transform Infrared spectroscopy to determine adulterants in raw milk

The objective of this study was to develop calibrations to determine the concentration of some milk adulterants by using the automated methodology of Fourier Transform Infrared (FTIR). For construction of calibrations, samples were collected from 100 farms in the states of Sao Paulo and Minas Gerais. Samples were tainted with three different adulterants commonly used in the adulteration of raw milk: sodium bicarbonate (SB), sodium citrate (SC) and cheese whey (W). Each adulterant was used at three different concentrations (SB: 0.05, 0.10 and 0.25%; SC: 0.025, 0.050 and 0.075% and W: 5, 10 and 20%). For validation, 60 samples were collected in other farms, which were not considered at the development stage of calibration. Adulterants were added at the following concentrations: 0.03, 0.06, 0.10 and 0.12% for SB; 0.02, 0.04, 0.06 and 0.08% for SC and 5, 10 and 20% for W. Performance of each calibration was evaluated in terms of accuracy (Se), detection limit (DL) and determination coefficient (R2). All calibrations presented R2 higher than 0.91 with DL of 0.015%; 0.017% and 3.9% for SB, SC and W, respectively. Accuracy was 0.005%, 0.009% and 2.26% for SB, SC and W, respectively. Results show that the FTIR methodology can be used for determining the concentration of sodium bicarbonate, sodium citrate and whey in raw milk. Associated with automated equipment, it is a viable option for monitoring these adulterants, having low operational costs and high analytical performance as additional features.

Electroless copper-phosphorus coatings with the addition of silicon carbide (SiC) particles

Cu-P-silicon carbide (SiC) composite coatings were deposited by means of electroless plating. The effects of pH values, temperature, and different concentrations of sodium hypophosphite (NaH2PO2·H2O), nickel sulfate (NiSO4·6H2O), sodium citrate (C6H5Na3O7·2H2O) and SiC on the deposition rate and coating compositions were evaluated, and the bath formulation for Cu-P-SiC composite coatings was optimised. The coating compositions were determined using energy-dispersive X-ray analysis (EDX). The corresponding optimal operating parameters for depositing Cu-P-SiC are as follows: pH 9; temperature, 90°C; NaH2PO2·H2O concentration, 125 g/L; NiSO4·6H2O concentration, 3.125 g/L; SiC concentration, 5 g/L; and C6H5Na3O7·2H2O concentration, 50 g/L. The surface morphology of the coatings analysed by scanning electron microscopy (SEM) shows that Cu particles are uniformly distributed. The hardness and wear resistance of Cu-P composite coatings are improved with the addition of SiC particles and increase with the increase of SiC content.

An assessment of Fourier Transform Infrared spectroscopy to identify adulterated raw milk in Brazil

The aim of this study was to evaluate the application of the methodology of Fourier Transform Infrared spectroscopy (FT-IR) to the identification of adulterated raw milk. A reference spectrum with 800 representative samples of the study area was built. Through the analysis of principal components, equations with a distinct number of factors were developed. For the validation test, 100 adulterated samples were used at three different concentrations of sodium bicarbonate, sodium citrate and non-acid cheese whey. Results indicate that the FT-IR can be used for the identification of adulterated milk with 0,05% and 0,075% of sodium bicarbonate and citrated respectively.

Thermosensitive properties of semi-IPN gel composed of amphiphilic gel and zwitterionic thermosensitive polymer in buffer solutions containing high concentration salt

In this study, a semi-interpenetrating polymer network (semi-IPN) gel, which consists of an amphiphilic N,N-dimethylacrylamide- co- N-isopropylacrylamide (DMAA- co-NIPAM) gel and an interpenetrating zwitterionic thermosensitive poly( N-isopropylacrylamide- co- N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate) (poly(NIPAM- co-DMAAPS)) was prepared. The thermosensitive behavior of the semi-IPN gel was investigated in a buffer solution composed of a relatively high concentration of sodium chloride and sodium citrate as salts, and sodium dodecyl sulfate as a surfactant, which are generally used as a buffer solution in biochips. At low temperatures, the semi-IPN gel in the buffer solution was absolutely transparent; however, when the gel was heated, the gel became milky white or opaque without a large change in the gel size. The network of the transparent gel is homogeneous, whereas that of the opaque gel consists of coarse and dense parts. Such a structural change in the gel network was confirmed by the temperature dependence of the permeability of the buffer solution through the semi-IPN gel membrane. The permeability increased drastically when the gel became opaque because of heating.

Substrate specificity of kallikrein-related peptidase 13 activated by salts or glycosaminoglycans and a search for natural substrate candidates

KLK13 is a kallikrein-related peptidase preferentially expressed in tonsils, esophagus, testis, salivary glands and cervix. We report the activation of KLK13 by kosmotropic salts and glycosaminoglycans and its substrate specificity by employing a series of five substrates derived from the fluorescence resonance energy transfer (FRET) peptide Abz-KLRSSKQ-EDDnp. KLK13 hydrolyzed all these peptides only at basic residues with highest efficiency for R; furthermore, the S3 to S2′ subsites accepted most of the natural amino acids with preference also for basic residues. Using a support-bound FRET peptide library eight peptide substrates were identified containing sequences of proteins found in testis and one with myelin basic protein sequence, each of which was well hydrolyzed by KLK13. Histatins are salivary peptides present in higher primates with broad antifungal and mucosal healing activities that are generated from the hydrolysis from large precursor peptides. KLK13 efficiently hydrolyzed synthetic histatin 3 exclusively at R25 (DSHAKRHHGYKRKFHEKHHSHRGYR25↓SNYLYDN) that is the first cleavage observed inside the salivary gland.In conclusion, the observed hydrolytic activities of KLK13 and its co-localization with its activators, glycosaminoglycans in the salivary gland and high concentration of sodium citrate in male reproductive tissues, indicates that KLK13 may play a role in the defense of the upper digestive apparatus and in male reproductive organs.

Wet chemical synthesis and photoluminescence properties of YVO4:Bi3+,Eu3+ nanophosphors

YVO4:Bi3+,Eu3+ nanoparticles were prepared by the wet chemical synthesis in various concentrations of sodium citrate, 15 ≤ xcit ≤ 90, where xcit is the nominal molar percentage of citrate relative to the sum of metallic ions, Y3+, Bi3+, and Eu3+. Mean primary particle size and mean hydrodynamic size in the aqueous colloidal solution have minimum values, 21 and 36 nm, respectively, for the sample prepared at xcit = 50 mol%. The transparency of the aqueous colloidal solution in the visible region increases with decreasing the mean hydrodynamic size, and hence the sample prepared at xcit = 50 mol% shows the highest transparency. YVO4:Bi3+,Eu3+ nanophosphor synthesized by the citrate route shows the photobleaching behavior, i.e., the decrease in photoluminescence intensity under the continuous irradiation of excitation light. This photobleaching property is remarkably suppressed by the washing post-treatment combined with centrifugation and the hydrothermal post-treatment. A relation between the fraction of photobleach and the amount of citrate ions coordinating to metallic ions at the surface of nanoparticles verifies that the photobleaching behavior of YVO4:Bi3+,Eu3+ nanophosphor originates from the redox reaction between the citrate ions and V5+ in YVO4 host crystal.

Self-Assembled β-NaGdF4 Microcrystals: Hydrothermal Synthesis, Morphology Evolution, and Luminescence Properties

A self-assembly process has been designed for the controlled synthesis of β-NaGdF(4) with uniform morphology, dimension, and considerable monodispersity under a gentle hydrothermal condition using sodium citrate as the chelating agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), and up-conversion (UC) photoluminescence spectra were used to characterize the samples. The results indicate that the NaGdF(4) microcrystal can be rationally modified in phase, size, and morphology through tuning the pH value, sodium citrate content, and reaction time. Moreover, the hybrid process of the crystal growth and the self-assembly were thoroughly discussed, and a possible formation mechanism was proposed. Furthermore, the UC luminescence properties as well as the emission mechanisms of β-NaGdF(4):17%Yb(3+)/3%Ln(3+) (Ln = Er, Tm, Ho) microcrystals were systematically investigated. It is found that under 980 nm excitation, only limited emission bands were discovered which can be attributed to the energy gap and migration function of the Gd(3+) ions in the β-NaGdF(4) microcrystals. It is expected that the synthetic strategy can be applied to prepare many other types of micro- and nanocrystals as well.

Surfactantless Photochemical Deposition of Gold Nanoparticles on an Optical Fiber Core for Surface-Enhanced Raman Scattering

Surface-enhanced Raman scattering (SERS) probes based on gold nanoparticles modifying the core of the optical fiber were made by a surfactantless photochemical deposition method. The growth kinetics and shape evolution of gold nanoparticles depending on different experimental conditions were studied. It was found that, under the condition of detectable gold nanoparticle deposition, increasing the concentration of chloroauric acid (HAuCl(4)) was not conducive to the deposition whereas increasing the concentration of sodium citrate (Na(3)Ct) would speed up the deposition. By controlling the concentration of the reaction solution and irradiation time, we obtained fused spherical-like, spherical, and flowerlike gold nanoparticles. To test the SERS activity of the probes, the SERS spectra of a rhodamine 6G aqueous solution were recorded in direct detection mode and remote mode. We have also developed a new approach to improving the SERS sensitivity when detecting in remote mode.

Hollow Gold Nanospheres: Growth Morphology, Composition and Absorption Characteristics

Gold hollow nanospheres (GHNs) were synthesized by using various stoichiometric ratios of chloroauric acid and cobalt nanoparticles as sacrificial templates through redox reaction of sodium borohydride. The self-assembly and crystallization process of GHNs were represented. The size of GHNs was dependent on the concentration of sodium citrate, sodium borohydride, and chloroauric acid. The composition of hollow nanospheres was analyzed for each growth strategy. It was notable that the core of the nanoshells contains significant traces of Co elements. The surface plasmon resonance peak of these hollow nanospheres shifts over 140 nm with varying nanostructure sizes. The GHNs are extremely useful for various molecular sensing applications.

Calcium Phosphate Cement Modified with Sodium Citrate for Bone Repair

An injectable calcium phosphate cement (CPC) modified with sodium citrate was developed in the present study. The effects of sodium citrate concentration on the injectability, mechanical strength, and the self-setting properties of CPC were systematically investigated. The addition of sodium citrate significantly improved injectability and compressive strength of CPC. The specimens have an injectability of 93% and compressive strength of 36.43 ± 2.64 MPa at 15 wt% sodium citrate concentration, compared to injectability of 75% and compressive strength of 23.15 ± 2.12 MPa of the specimens without sodium citrate. XRD spectra indicated that addition of sodium citrate did not change the hydration reaction of CPC and the reaction product was mainly poorly crystallized hydroxyapatite. In conclusion, CPC developed in this work exhibited excellent injectability and high strength, which should be a promising material for bone repair.

The Research on Coating of Electroless Ni-W-P Ternary Alloys

The ternary Ni-W-P alloy coatings were deposited on the surface of Q235 steel using Chemical deposition. The microstructure, phase analysis, plating velocity and hardness were investigated with scanning electron microscope, X-ray diffraction technique and Vickers hardness tester. The results showed that the plating rate had been increased firstly, and then decreased with the increment of sodium citrate concentration in the range of 20-80g/L, the maximum plating velocity was 9.14μm/h. The hardness of Ni-W-P plating increased first and then decreased with the increment of sodium citrate concentration, the maximum hardness was 643HV when the concentration of sodium citrate was 40g/L. When the concentration of sodium citrate was 40g/L, the substrate was completely covered by Ni-W-P plating, the surface was composed of uniform crystalline grains, and had no obvious defects and presented amorphous. The coating and substrate were relatively strong, the coating had no the phenomena of fall off and crackle in the bending and files tests when the concentration of sodium citrate was 40g/L and 50g/L respectively.