Papers by Keyword: Phosphates

Abstract: Water resources are crucial in any region's overall natural resource complex. This research focuses on addressing these pollution issues through water treatment processes. The primary objective of this study was to examine the adsorption of phosphates using both natural and synthetic adsorbents, particularly aluminosilicates. Under static and dynamic conditions, the research assessed the sorption characteristics of natural zeolite, specifically clinoptilolite obtained from the Sokyrnytsia mineral deposits. Results indicated that the adsorption of phosphates is more effective in acidic environments. It was observed that clinoptilolite exhibits a higher adsorption capacity for unsubstituted phosphates, which diminishes when alkali metal ions replace orthophosphoric acid. Additionally, the study highlighted the significant influence of pH levels on the sorption properties of clinoptilolite, especially about P₂O₅. The kinetic coefficients of the adsorption process were determined using experimental data and theoretical frameworks. Furthermore, mathematical modelling was employed to describe the adsorption dynamics of the active components by granular sorbents, effectively capturing the transient nature of diffusive-kinetic processes in complex, multicomponent systems. This research deepens our understanding of phosphate adsorption mechanisms. It provides valuable insights into optimising water treatment strategies using natural adsorbents, which could play a critical role in mitigating the effects of water pollution in the region. Zeolites derived from fly ash produced by the Dobrotvir thermal power plant have been synthesised and modified to enhance their properties. This study focuses on the characteristics of these zeolites, with a particular emphasis on thermogravimetric analysis, to understand their stability and performance under varying conditions. The adsorption capabilities of the natural zeolite were tested against common pollutants found in wastewater from meat-processing plants, specifically targeting ammonium and phosphate contaminants. Experimental data allowed for determining equilibrium adsorption capacities and corresponding isotherms were constructed at a standard temperature of 20°C. The results indicate that zeolite adsorbs phosphates more effectively than ammonia nitrogen. Further analysis revealed that clinoptilolite's adsorption capacity is higher when interacting with single-component systems but decreases when it simultaneously adsorbs two different substances from the solution. This decrease suggests competitive adsorption dynamics when multiple contaminants are present. Given the finite availability of natural zeolite resources, this research highlights the importance of synthesising synthetic zeolites as a sustainable alternative.

Abstract: The present study focuses on the preparation and use of biosorbents produced from eggshells. Hen eggshells are produced as a by-product in large quantities by food manufacturers. The costs associated with eggshell disposal (mainly on landfill sites) are significant and expected to continue increasing as landfill taxes increase.The environmental significance of phosphorus arises from its role as a major nutrient for both plants and microorganisms. The adsorption efficiency of phosphate ions from the obtained biosorbents - raw eggshell powders - is studied at room temperature in static conditions. The effect of phosphate concentration and sorbent mass on the efficiency of the process is evaluated, as well as sorption kinetics are investigated. The structure, phase composition, porosity, specific surface area and morphology of obtained biosorbents is determined. The utilization of eggshells as an abundant, cheap and biodegradable material for the removal of phosphates is studied and discussed.

Abstract: The study deals with the one of the important feature of alkali activated blast furnace slag which is very rapid initial setting. Therefore, the influence of the retarding agents such as phosphates was tested. It is shown that phosphates decreases the hydration heat evolution and retards the hydration reaction of alkali activated slag effectively. The mechanism of retardation is studied through the microcalorimeter and electron microscopy equipped with energy dispersive analyzer (SEM-EDS). The optimal dosage of suitable retarding admixture in the means of mechanical properties has been determined.

Abstract: YPO₄ nanowires (NWs) and nanoparticles (NPs) have been synthesized by hydrothermal methods respectively in the absence and presence of EDTA. The Eu³⁺ and Yb³⁺ codoped YPO₄ NWs and NPs prepared directly from hydrothermal systems show efficient red down-conversion luminescence (DL) and upconversion luminescence (UL) at room temperature without further annealing process. EDTA plays a critical role in controlling the morphologies of YPO₄ nanocrystals in hydrothermal systems and enhances both the DL and UL intensities of Eu³⁺ by the factor of 100%. Monodispersed Eu³⁺ and Yb³⁺ codoped YPO₄ NPs will be a new candidate for application in infrared displays and biological labels.

Abstract: Solid solution BiP_0.9V_0.1O₄ from BiP_XV_1-XO₄ system has been synthesized by solid state synthesis at 973 K. It has been shown that the phosphate-vanadate can be prepared as a single phase for x =0.9, while higher degree of (P/V)O₄ substitution in BiVO₄ has not been detected for the range studied. The substitution peculiarities have been investigated by X-Ray powder diffraction, infrared and photoluminescence spectroscopy. The luminescence spectrum of BiP_XV_1-XO₄:Eu³⁺ solid solution reveal intensive photoluminescence lines related to f-f electronic transitions in Eu³⁺ ions.

Abstract: In the present study, we fabricated the amorphous zirconium oxides by the classic sol-gel precipitation methods. SEM analysis proved that the prepared ZrO₂ particles are micrometer scales and XRD further illustrated its amorphous nature. The effects of solution pH on adsorption suggests the phosphate retention onto ZrO₂ was a pH-dependent process and the optimum pH values between 4.5-8.0; competition tests also demonstrated its excellent selectivity by comparing D201 resin in presence of common anions at high levels. All the results proved that ZrO₂ is a promising adsorbent for P(V) sequestration.

Abstract: Phosphate is widely used in frozen aquatic products. In this study, frozen Pollock was taken as raw materials, and the effect of different phosphates (sodium pyrophosphate, sodium tripolyphosphate and sodium hexametaphosphate) on weight gain, thawing loss and cooking yield of Pollock fillets were studied. The results showed that with the increasing concentration, the weight gain and cooking yield of sodium pyrophosphate and sodium tripolyphosphate treatment groups increased, and the thawing loss reduced, whereas sodium hexametaphosphate treatment group remained unchangeable. The optimal proportion of sodium pyrophosphate, sodium tripolyphosphate and sodium hexametaphosphate on Pollock fillets was 3:2:3 and the concentration of mixed phosphates was 4%, and the weight gain, cooking yield and thawing loss was 17.1%, 88.6% and 2.7%, respectively