Papers by Keyword: Phosphate

Abstract: Many factors influence the effectiveness of traditional binders used for soil stabilization, including anions present in the soil and carbonates. Natural pozzolana-lime stabilization is a relatively new technique that has shown promising results. However, no study has specifically evaluated its success in the presence of phosphate for high-carbonate soils. This paper investigates this question using marly soil from Medea, which was pre-contaminated with the common fertilizer monoammonium phosphate at 0, 2, 4, and 6% by dry weight, then stabilized with lime and/or natural pozzolana at 0, 8%, and 20%, respectively, by dry weight. To assess the effect of phosphate, mineralogical and macrostructural changes in these mixtures were analyzed through X-ray diffraction tests and scanning electron microscopy, respectively. Additionally, pH levels were monitored over 90 days, and changes in Atterberg limits between 1 and 30 days of curing were compared. Variations in immediate bearing indexes and compaction parameters were also examined. The study found that lime alone was ineffective in stabilizing the soil due to high carbonate content, with improvements in geotechnical properties only observed when natural pozzolana was added with lime. Phosphate was found to impact the lime-natural pozzolana stabilization technique significantly.

Abstract: Phosphorus scale inhibitor is a kind of agent which can disperse insoluble inorganic salts in water, prevent or interfere with the precipitation and scaling of insoluble inorganic salts on metal surface, and maintain better heat transfer effect of metal equipment. Sodium triethylenetetramine hexamethylphosphonate (TETHMPS) and tetraethylenepentamine heptagon methylene phosphonic (TEPHMPS) were prepared by one-step synthesis method. The effects of temperature, concentration and mixing ratio on scale inhibition were investigated. The results showed that as the concentration of TETHMPS and TEPHMPS increases, the scale inhibition rate increases. At the same temperature, compared with TETHMPS, TEPHMPS has better scale inhibition performance, and the maximum scale inhibition rate can reach 93.59%. The scale inhibition rate of the synthesized scale inhibitor at 80 °C is better than that at 60 °C. The scale inhibition performance of the compound scale inhibitor is better than that of the single scale inhibitor, showing an ideal synergistic effect. When the concentration is 60 mg/L, the scale inhibition rate of TETHMPS is 94.26%, TEPHMPS is 94.55%, and the scale inhibition rate is above 91%.

Abstract: Compared with inorganic phosphonates, organic phosphonates have better chemical stability in water treatment, and are not easy to hydrolyze in higher temperature and wider pH range. In this paper, a one-step synthesis method of ethylene diamine tetra (methylene phosphonic acid) sodium (EDTMPS) and methylene phosphonic acid (DTPMPA) were studied. A new phosphate scale inhibitor was prepared and its scale inhibition performance was evaluated. The results showed that the scale inhibition rate increased with the increase of the concentration of synthetic products (EDTMPS, DTPMPA). At the same concentration, compared with DTPMPA, EDTMPS has better scale inhibition performance, and the maximum scale inhibition rate can reach 96.85%. The scale inhibition performance of composite scale inhibitor is better than that of single scale inhibitor, and the scale inhibition rate of the synthesized products can reach more than 90% after compounding. And inhibitory mechanism has been proposed: Because phosphonates effectively control the rate of nucleation. In addition, polyphosphonates can chelate Ca²⁺, Mg²⁺ plasma to form monocyclic or bicyclic chelates. This will destroy the normal growth process of calcium carbonate and other crystals, thus preventing the formation of calcium carbonate scale.

Abstract: Catalytically active cerium dioxide is used as light reflection materials for cosmetic applications. Therefore, cosmetics containing this pigment too much cause oxidation of the skin. Therefore, the substitute for cerium dioxide is required to prepare the cosmetics without catalytic activity. Herein, as novel white pigments for use in cosmetics, cerium phosphates were prepared from cerium oxalate under various conditions. The chemical composition, powder properties, catalytic activity, color phase, and smoothness of the cerium phosphates were evaluated. All samples had weak unknown peaks in XRD patterns. Samples prepared at high temperature and for long time indicated the peaks of phosphate in IR spectra. Samples prepared in this work had no photo and oxidation catalytic activities. Samples prepared at high temperature and for long time indicated enough high whiteness and high smoothness.

Abstract: Tuning the concentration of nanoparticles (NPs) to accommodate wider application demanded a better understanding of the physicals and structural properties of the glass. A series of zinc phosphate glasses with the composition of (57-x) P₂O₅- 40ZnO-3Tb₂O₃ –xCuO, (0 ≤ x ≤ 2 mol %) has been prepared by melt quenching technique and their physical and optical characterization have been studied. The X-Ray Diffraction technique and UV-Vis Spectroscopy have been used to characterize the glass sample. The XRD confirms the amorphous nature of the prepared glasses. The physical properties of glasses with different CuO NPs such as density, molar volume, refractive index and electronic polarizability are determined. It is found that both density and molar volume decreases with increasing CuO NPs concentration. The optical band gap (4.54 eV-2.96 eV) and the Urbach energy (0.19 eV-0.54 eV) are showing a decreasing trend with the increasing amount of CuO NPs.This is due to the formation of non-bridging oxygen, (NBO) in the glass network. The glass exhibits high refractive index ~2.40 and polarizability ~1.12 ×10^-23 cm³ and is useful for solid-state laser and optoelectronic devices.

Abstract: In order to improve the anticorrosion ability of a Mg-5Zn-1.5Ca alloy used as a bone replacement material, this study prepared the MnCaP conversion coating, which was formed from a phosphating solution mixed with a MnCl₂ solution of 0.05 molarity, on a magnesium (Mg) alloy. After forming a MnCaP conversion coating on a Mg alloy, micro-arc oxidation (MAO) proceeded for improving the anticorrosion ability of the sample. As a result, when the 0.05MnCaP coating on a Mg alloy was immersed in the simulated body fluid (SBF), the corrosion current, pH value change, and hydrogen evolution volume of the SBF solution are lower than a uncoated Mg alloy. From the SEM and EDS analyses for a corroded 0.05MnCaP coating on a Mg alloy, the manganese (Mn) phosphate in a lumpy-rock form and the calcium (Ca) phosphate in a flake form alternate to each other densely, so that the coating can effectively prevent a Mg alloy from corrosion.

Abstract: The aim of this work was to study the potential of the agricultural waste byproduct as a low-cost adsorbent for removal of phosphate ion (PO₄^3-) from synthetic wastewater. The simple preparation of carbonized filter cake (CFC) was performed at 550°C. CFC was also characterized using FTIR, X-ray fluorescence analysis. The adsorptive parameters of batch experiment, such as pH of solution, dosage and contact time were systematically studied in order to the optimization condition. The optimum conditions of pH, contact time and adsorbent dose were to be 6, 60 min, and 2 g/L, respectively. The Langmuir and Freundlich isotherms were used to calculate the adsorption parameters that was able to describe the equilibrium isotherm and adsorptive mechanism. The maximum monolayer adsorption capacity of CFC was estimated as 20.32 mg/g. The optimized condition was applied for phosphate removal from synthetic wastewater. The achieved phosphate removal efficiency from synthetic wastewater sample was to be 92.4%. Filter cake is a low-cost byproduct of sugar cane but it can also highly effective remove phosphate ion from aqueous solution. The modification of filter cake surface via chemical reaction as a new adsorbent in order to increase surface sites and high affinity with phosphate ion will also be further studied.

Abstract: The objective of this work is to study the phosphate adsorption from natural waters by using a granular activated carbon (GAC). Experiments were carried out with synthetic solutions of phosphate prepared using groundwater (mineralized drinking water). Batch tests were carried out in order to study different operating parameters such as the effect of contact time, pH, initial phosphate concentration and adsorbent dosage. In addition, the adsorption kinetic data were simulated using the pseudo first order, the pseudo second-order and the intra-particle diffusion model. The sorption equilibrium was analyzed by Langmuir, Freundlich and Dubinin–Radushkevich isotherms model. Results show that the phosphate adsorption was reversible and the quantity adsorbed reached its maximum value (2.82 mg/g) after 30 min. It was also found that phosphate uptake was affected by variation of pH, initial concentration of phosphate and granular activated carbon dosage. The adsorption improved with increase in pH values, initial concentration and adsorbent dosage. The results of kinetic studies revealed that pseudo-second-order model adequately described the adsorption phosphate on GAC and the intra-particle diffusion involved in the adsorption mechanism. Also, isotherm study showed that Langmuir isotherm best fit the data and the adsorption was a physical type.

Abstract: Partially phosphorylated poly vinyl alcohol (PPVA) was mixed with two different aluminum (Al) sources (aluminum nitrate and aluminum hydroxide) to produce a PPVA-AlPO₄ composite. Transgravimetric analysis (TGA) shows that the weight residue of PPVA-AlPO₄ composite using aluminum nitrate is higher than aluminum hydroxide. X-Ray diffraction (XRD) analysis shows the occurrence of multiple phases of PPVA-AlPO₄ composite using aluminum nitrate and three broad peaks at range of 2-6, 6-18 and 24-36 ̊ using aluminum hydroxide.

Abstract: Marine structure, coralline materials were converted to calcium phosphate using two different phosphate solutions. The aim was to study the conversion mechanisms under acidic and basic environment at moderate conditions of temperature. Crystal growth and morphology of converted corals were characterized by XRD and SEM respectively. The results suggested that under acidic conditions (H₃PO₄), dissolution and precipitation control and direct the crystal formation and morphology in which transition from plate like to rod like hydroxyapatite structure was favoured. Metastable phase such as monetite formed and transformed to HAp during reaction. During the first hour of the dissolution a monetite and hydroxyapatite mixture precipitates and then the full conversion to hydroxyapatite is observed. On the other hand, under basic conditions (NH₄)₂HPO₄, just diffusional surface conversion of the calcium carbonate structure of coralline materials to hydroxyapatite and a very small amount of tri-calcium phosphate is observed. The mechanism can be classified as the solid-state topotactic ion-exchange reaction mechanism.