جستجوی مقالات مرتبط با کلیدواژه « strontium » در نشریات گروه « علوم پایه »

Due to the importance of removing strontium ions in nuclear wastes, in the present work, while synthesizing hydroxybenzaldehyde propyltriethoxysilane ((EtO)3Si-HL) and pyridylmethylidene propyltriethoxysilane ((EtO)3Si-L) ligands, we investigated the properties of silica nanoparticles modified with these ligands as solid adsorbents in The removal of strontium ion from the aqueous solution was investigated and parameters such as pH, time, the mass of adsorbent, temperature, and interfering ions were tested. The adsorption behavior of the adsorbents showed that by modifying the surface of the nano adsorbent, the ability of the adsorbents to adsorb strontium ion at pH=6 increased from 6.31% to 86% and 22.11% using the (EtO)3Si-HL and (EtO)3Si-L ligands, respectively. The results of isotherms and adsorption kinetics indicate that the adsorption process follows the Longmuir isotherm and the pseudo-second-order model, respectively. Also, thermodynamic parameters show that strontium removal from the aqueous solution is an endothermic process. The positive entropy values are the driving force behind the adsorption process.

This research investigates the transfer factor in the soil to plant (as one of the important parameters in safety analysis calculations and determining the amount of radiation of people) of strontium ion (a conventional radionuclide in pollution caused by nuclear accidents) to two plant samples including radish (Raphanus sativus var. sativus) and watercress (Lepidium sativum) as highly consumed plants in the food chain grown in the southern soil of Tehran. In this research, experiments were carried out in pots with a diameter of 15.5 cm and a height of 15.7 cm. These pots contained 2 kg of soil mixed with compost under the natural sunlight conditions of Tehran. In order to investigate the effect of strontium ion concentration on the transfer factor, the desired soil was first mixed with compost at a ratio of 3:1 and, using strontium nitrate salt solution in four different concentrations (50-200-500-1000 mg/kg) was infected. Pots were irrigated weekly with a specific volume of water at two different acidity levels (pH = 5 and 6) to investigate the effect of pH on the transfer factor. Also, the concentration of strontium ions in two tissues of the leaf and root of radish and watercress was done. This was examined to determine the accumulation of strontium ions in each of the tissues and their influence on the transfer factor. The results showed that with the increase in soil strontium concentration, the amount of adsorption of this element in both plants increases and the transfer factor decreases. Also, the plant had more adsorption in the soil with lower pH and a higher transfer factor was reported. The comparison of transfer factor and strontium adsorbed between the two plants also showed that radish adsorbed more strontium than watercress and had more transfer factor. Also, using an experimental method, the distribution coefficient, which is a crucial and practical parameter in pollutant transfer modeling and pollution risk assessment in soil and water resources, was determined by using the transfer factor from soil to plant. In this research, the possibility of decontamination of strontium from the soil by applying radish was investigated. The results showed that this plant could be used as a purifier to purify soils contaminated with strontium.

This study investigates the distribution coefficient of strontium in a soil sample in the south of Tehran. In this research, the columnar method  was used to determine the distribution coefficient of strontium. Also, the effect of three factors, pH, strontium concentration, and soil height in the column was studied using the RSM method's experimental design. For this purpose, five different levels were considered for each parameter, and the experiments were designed and performed by MiniTab software. According to the results obtained in the predicted model, pH, column height, interaction between pH and column height, the interaction between pH and strontium concentration, and interaction between strontium concentration and column height are important. The square of the coefficients as well as the concentration of strontium, did not have much effect on the distribution coefficient. The most significant effect is due to the height of the column, which increases with increasing the height of the column. The rate of conformity of the predictive equation with the actual values ​​is 96.39%, which is an acceptable value.

Graphene-based nanomaterials are being investigated for their biocompatibility and bioactivity, as well as their ability to improve osteogenic differentiation. In this research, the base material, reduced graphene oxide (rGO) sheets, were decorated with hydroxyapatite and strontium (rGO / HAp-Sr) to induce osteogenic differentiation in adipose-derived mesenchymal stem cells. Different techniques were used to determine the properties of the nanocomposite such as diffraction analysis techniques (XRD) and transmission electron microscopy (to evaluate the size and morphology of HAp-Sr on rGO plates), FT-IR (to analyze the nanocomposite functional group), Raman spectroscopy (to investigate possible disorders in nanocomposite structure and number of layers), induced dual plasma emission spectroscopy (to assess atomic concentration of Ca and Sr), zeta potential(electrical potential of the nanocomposite) and MTT (nanocomposite cytotoxicity assessment) were used. The ossification potential of the synthesized nanocomposite was investigated and confirmed using the calcium deposition test in dipose-derived mesenchymal stem cells. According to the obtained results, osteogenic differentiation induction is possible using synthesized nanocomposites without the need for chemical inducers.