Aqueous Sodium Phosphate Solutions Research Articles

Development of a method for fire-resistant finishing of non-woven material using a phosphorus-containing composition

The aim of the study is to obtain a non-woven material with flame retardant properties. The conditions of the process of fire-retardant finishing were as follows: an aqueous solution of preparations of various concentrations was applied by spraying onto the surface of the material, then drying was carried out and heat treatment on a thermal press. According to GOST R 50810-95, non-woven material made from flax and wool fibers, treated with a composition based on an aqueous solution of sodium phosphate and guanidine hydrochloride, is classified as a flame-retardant material. Also, tests for toxic and skin-irritating effects of non-woven material treated with the proposed composition showed its safety for human health.

Natrophosphate, Arctic Mineral and Nuclear Waste Phase: Structure Refinements and Chemical Variability

The crystal structures of natural (Mt. Koashva, Khibiny alkaline massif, Kola Peninsula, Russian Arctic) and synthetic (obtained from an aqueous solution of sodium phosphate and sodium fluoride (1:1) by evaporation at room temperature (RT)) natrophosphate, Na7(PO4)2F·19H2O, have been investigated using single-crystal X-ray diffraction analysis. Natrophosphate and its synthetic analogue are cubic, Fd-3c, a = 27.6942(3) Å (natrophosphate at RT), a = 27.6241(4) Å (natrophosphate at 100 K), a = 28.1150(12) Å (synthetic analogue at RT), a = 27.9777(7) Å (synthetic analogue at 100 K). The crystal structure is based upon the super-octahedral [Na6(H2O)18F]5+ polycationic complexes consisting of six edge-linked Na6(OH2)5F octahedra sharing one common fluorine vertex. The A site is statistically occupied by Na and H2O with the prevalence of H2O with the refined occupancy factors O:Na equal to 0.53:0.47 for natrophosphate and 0.75:0.25 for its synthetic analogue. The coordination of the A site in synthetic natrophosphate is enlarged compared to the natural sample, which agrees well with its higher occupancy by H2O molecules. The general formula of natrophosphates can be written as Na6+xHxF(PO4)2·(19 + x)H2O, where x = 0–1. The chemical variability of natrophosphate allows to explain the discrepancies in its solubility reported by different authors. The information-based parameters of structural complexity are equal to 3.713 bit/atom and 2109.177 bit/cell that allows to classify natrophosphate as a structurally very complex mineral.

Novel bioceramics from digital light processing of calcite/acrylate blends and low temperature pyrolysis

Porous bioceramic composites with complex shapes were easily fabricated starting from fine calcite (CaCO3) particles (<10 μm) immersed in a liquid photocurable polymer. The building of 3D structures, layer-by-layer, was achieved by means of Digital Light Processing (DLP), using a commercial stereo-lithography 3D printer. The pyrolysis of the hardened photosensitive polymer, in nitrogen atmosphere (at 500 °C), left calcite powders embedded in an amorphous carbon matrix, without any degradation of the main phase, which retained its biocompatibility, according to the cell culture studies. In addition, calcite was successfully converted into hydroxyapatite (HAp), by simple immersion of samples in a phosphatizing bath (aqueous solution of sodium phosphate), for 2 weeks, obtaining HAp-pyrolytic carbon composite scaffolds. The developed structures, after phosphatization, exhibited an adequate strength-to-density ratio (compressive strength of 1.4 MPa with porosity of about 80 vol%).

Adsolubilisation of thiacloprid pesticide into the layered zinc hydroxide salt intercalated with dodecyl sulphate, for controlled release formulation

ABSTRACT Sodium dodecyl sulphate surfactant was intercalated into the layered zinc hydroxide salt for the successful adsolubilisation of poor water-soluble pesticide, thiacloprid. The intercalation of the dodecyl sulphate ion was confirmed by PXRD analysis with basal spacing 30.1 Å. The presence of thiacloprid into the interlayer gallery of zinc layered hydroxide also supported with Fourier transform infrared spectra and elemental analysis. Based on the thermal study, thiacloprid was thermally stable after the adsolubilisation compared to its solid form. The release of thiacloprid anions from the nanocomposite into an aqueous solution of sodium phosphate was governed by first-order kinetics. Whereas the release of thiacloprid into sodium sulphate and sodium chloride solution governed by parabolic diffusion kinetics model. In consideration of the obvious breakthrough made in the nanocomposite characterisation and release study, this nanocomposite could be a promising candidate for the profitable improvement of an environment-friendly pesticide formulation.

Silica-bonded apatite scaffolds from calcite-filled preceramic polymers

Silica-bonded apatite ceramics were successfully fabricated starting from preceramic polymers, in the form of silicone resins, incorporating powdered calcite (CaCO3). Silicone-calcite slurries were used for infiltrating sacrificial reticulated PLA scaffolds obtained by direct 3D printing. After cross-linking the mixture at room temperature, the samples were thermally treated at 350°C to burn out the PLA, thus obtaining the desired scaffolds by negative replica. The samples were later ceramized at 600°C, avoiding the decomposition of CaCO3. A further treatment was applied to convert calcite into apatite (Ap), by immersion of samples in a phosphatizing bath (aqueous solution of sodium phosphate). It was demonstrated that the same procedure could be followed when replacing commercial CaCO3 with a material of biological origin, i.e. eggshell waste, resulting in a more extensive CaCO3-to-Ap conversion. The formation of the desired crystalline phases was assessed by means of XRD analysis. The scaffolds were found to exhibit a porosity between 57 and 69%, considering both the voids in the reticulated structure and the micro-sized porosity of the struts, and an excellent compressive strength, in the order of 13–16MPa.

Arginine as an eluent for automated on-line Protein A/size exclusion chromatographic analysis of monoclonal antibody aggregates in cell culture

An automated two-dimensional method using Protein A chromatography followed by size exclusion HPLC was developed for analysis of aggregates of monoclonal antibodies in mammalian cell culture samples. The method development was intended to address the analysis of IgG2 monoclonal antibody products that are particularly prone to aggregation at pH<3.5. An aqueous solution of sodium phosphate at pH 4.3 containing arginine was demonstrated in this work as an excellent eluent for Protein A chromatography. In addition, the arginine solution is a compatible mobile phase for the analysis of these samples by size exclusion HPLC, separating aggregates from the monomer of the monoclonal antibody. The effect of arginine concentration in the eluent on parameters such as protein recovery from Protein A chromatography and resolution of aggregates from the monomer are reported. The developed method was shown to provide accuracy of reported aggregates greater than 98%, and intermediate precision of 4.4% RSD. The method limit of quantitation for aggregates was determined to be 0.1%. Application of the method is demonstrated for analysis of aggregates in cell culture samples to aid in the development of cell culture conditions for the production of antibodies.

Volumetric and viscosity studies of interactions between sodium phosphate salts and poly(propylene glycol) 400 in aqueous solutions at different temperatures

Density and sound velocity at the 288.15–313.15 K and viscosity at the 298.15–313.15 K temperature range at 5 K intervals for polypropylene glycol (PPG) in aqueous solutions of sodium di-hydrogen phosphate, di-sodium hydrogen phosphate and tri-sodium phosphate with salt mass fractions 0.00, 0.010 and 0.020 are reported at atmospheric pressure. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined. The infinite dilution apparent specific volume and isentropic compressibility values of PPG have been obtained and from which the infinite dilution apparent specific volumes of transfer of PPG from water to aqueous sodium phosphate solutions have been obtained for the investigated salt concentrations and temperatures. The excess specific volume, isentropic compressibility and viscosity deviation are negative and decrease in magnitude as temperature, concentration of sodium phosphate and charge on the anion of electrolyte increases.

Adsorption of Phosphate on Goethite. An Undergraduate Research Laboratory Project

We present a freshman laboratory experiment on the adsorption of phosphate on goethite as a case study that opens the doors to the discussion of surface properties, interphases, acid–base equilibrium, molecular structure, and solid state chemistry, among other topics. We also describe a pedagogical implementation of this experiment that allows the students to work cooperatively, enhancing the feeling of community of the course. In this work students approach the study of adsorption of phosphate on an iron oxide as a function of pH, total ligand concentration, and ionic strength of the solution. This is achieved by adding an aqueous solution of sodium phosphate of known concentration to a suspension of goethite, allowing the system to equilibrate and then determining the concentration of phosphate not adsorbed on the surface of the oxide in the supernatant solution. These experiments are performed in different pH and ionic strength conditions to evaluate the role of these variables on the adsorption proces...

Properties of magnesia compositions as a function of the storage time of phosphate binder

The admissible storage time of a phosphate binder (30% aqueous solution of sodium phosphate) is shown to be at most 10 days. Sodium polyphosphate with -n = 20-25 is recommended as an optimum binder for periclase and periclase-chromite compositions. Specimens of periclase mixtures are shown to possess the best properties.

Zinc(II) oxide solubility and phase behavior in aqueous sodium phosphate solutions at elevated temperatures

A platinum-lined, flowing autoclave facility is used to investigate the solubility/phase behavior of zinc(II) oxide in aqueous sodium phosphate solutions at temperatures between 17 and 287°C. ZnO solubilities are observed to increase continuously with temperature and phosphate concentration. At higher phosphate concentrations, a solid phase transformation to NaZnPO4 is observed. NaZnPO4 solubilities are retrograde with temperature. The measured solubility behavior is examined via a Zn(II) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reaction equilibria are obtained from a least-squares analysis of the data. The existence of two new zinc(II) ion complexes, Zn(OH)2(HPO4)2− and Zn(OH)3(H2PO4)2−, is reported for the first time. A summary of thermochemical properties for species in the systems ZnO−H2O and ZnO−Na2O−P2O5−H2O is also provided.

Expedient liquid chromatographic analysis of azathioprine in plasma by use of silica solid phase extraction.

We report an expedient analysis of azathioprine (AZN) in plasma by use of a radial compression liquid chromatography and silica solid phase extraction. The separation of the drug and internal standard (antipyrine) was achieved on a C18 cartridge using a mixture of 0.01 M aqueous solution of sodium phosphate (pH = 4.5) and methanol (87:13; vol/vol) as the mobile phase. The assay is highly specific with no interference from any endogenous substance or concomitantly used drug. The peak height ratio of drug to internal standard was linearly (r greater than 0.09976) related to concentration in the range 0.005-2 micrograms/ml, and the within-run and between-day coefficient of variation did not exceed 6.9% at any concentration. This study measured the steady-state concentration of azathioprine in plasma of renal transplants patients. Also, the applicability of this method to study the pharmacokinetics of AZN following a single intravenous administration was examined, using the rabbit as an in vivo model.

Copper(II) oxide solubility behavior in aqueous sodium phosphate solutions at elevated temperatures

A platinum-lined, flowing autoclave facility is used to investigate the solubility behavior of copper(II) oxide (CuO) in aqueous sodium phosphate solutions at temperatures between 19 and 262°C. Copper solubilities are observed to increase continuously with temperature and phosphate concentration. The measured solubility behavior is examined via a Cu(II) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reactions are obtained from a leastsquares analysis of the data. Altogether, thermochemical properties are established for five anionic complexes: Cu(OH) , Cu(OH) , Cu(OH) 2 (HPO 4 ) 2− , Cu(OH) 3 (H 2 PO 4 ) 2− , and Cu(OH) 2 (PO 4 ) 3− . Precise thermochemical parameters are also derived for the Cu(OH)+ hydroxocomplex based on CuO solubility behavior previously observed (Ref. 3) for pure water at elevated temperatures. The relative ease of Cu(II) ion hydrolysis is such that Cu(OH) species become the preferred hydroxocomplex for pH≥9.4.

Solubility and phase behavior of nickel oxide in aqueous sodium phosphate solutions at elevated temperatures

A platinum-lined, flowing autoclave facility was used to investigate the solubility/phase behavior of nickel oxide (NiO) in aqueous sodium phosphate solutions between 290 and 560 K. A layer of hydrous nickel oxide was concluded to exist on the nickel oxide surface below 468 K; only at higher temperatures did the anhydrous nickel oxide phase control the nickel ion solubility behavior. The measured solubility behavior was examined via a nickel(II) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reaction equilibria were obtained from a least-squares analysis of the data. The existence of two new nickel ion complexes are reported for the first time: Ni(OH)2(HPO4)= and Ni(OH)3(H2PO4)=. The positive entropy change associated with the formation of Ni(OH)3(H2PO4)= leads to its dominance in alkaline phosphate solutions at elevated temperatures.

Phase equilibria in aqueous sodium phosphate solutions at elevated temperatures

Solubility and phase studies for the system Na2O–P2O5–H2O have been carried out at 251 and 300 °C and at the vapour pressures of the solutions. The experiments have been largely confined to the region of composition between the mol ratio Na2O : P2O5= 1.8 and 10.0. At both temperatures, the more alkaline saturated solutions are in equilibrium with a solid phase, 11 Na2O·4P2O5·3H2O, a complex orthophosphate. The less alkaline saturated solutions are in equilibrium with Na2[HPO4] at 251 °C, and with Na4[P2O7] at 300 °C. However, at the higher temperature, a region of liquid–liquid immiscibility also exists.