Isothermal, Kinetic, and Thermodynamic Studies on the Adsorption of Molybdenum by a Nanostructured Magnetic Material

In this study, the magnetic 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) – poly (4-vinylpyridine) (P4VP) was synthesized and characterized. Removal of Molybdenum (Mo) from aqueous solutions using prepared material as nanosorbent was investigated. The magnetic P4VP was prepared by copolymerization of P4VP with TMSPMA. The prepared adsorbent was characterized by various techniques including the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The batch adsorption technique was applied and the effect of several important parameters such as pH of the aqueous solution, adsorbent dose, initial Mo(VI) concentration, contact time, and temperature was evaluated. Desorption behavior of Mo(VI) and the effect of foreign ions (Cd2+, Ca2+, Co2+, Fe3+, Ba2+ and Pt4+) in real samples were also investigated. Co (II) and Pt (IV) had a greater impact on the adsorption process than other foreign ions. The maximum capacity for Mo(VI) adsorption on the prepared adsorbent was 4.87 mg/g, which was obtained at a temperature of 40°C with an initial concentration of 10 mg/L of Mo(VI). The adsorption isotherms were best fitted with the Weber Van Vliet isotherm model. The kinetic data were fitted well with the pseudo-second-order equation with a high correlation coefficient (R2 > 0.99). Based on the negative standard Gibbs free energy change (ΔG° 0), it was found that the adsorption was an endothermic and a spontaneous process in nature

Extraction-separation of Eu(III)/Th(IV) Ions with a Phosphorylated Ligand in an Ionic Liquid

ABSTRACT: Extraction-separation of Eu(III) and Th(IV) ions from nitrate media into the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate by a phosphorylated salen extractant, bis(chlorophosphoryle)decahydro-2,4-di(2-hydroxyphenyl)benzo[d][1,3,6]oxadiazepine (DPO), is investigated. It is found that Eu(III) ions are extracted via a solvation mechanism, and the extraction of Th(IV) ions proceeds through an ion exchange mechanism. The analysis of the experimental data reveals that the extraction of Eu(III) and Th(IV) ions is taken place by formation of Eu(DPO)(NO3)3 and Th(DPO)2(PF6)4 complexes. A significant selectivity towards thorium ions with respect to trivalent lanthanides was observed. Thorium(IV) can be efficiently extracted from nitric acid solutions into the studied ionic liquid in the presence of DPO

Adsorption behavior of trace elements of 90Sr on MnO2–ZrO2 loaded with polyacrylonitrile polymer from aqueous solutions

Abstract A MnO2–ZrO2-polyacrylonitrile (MnO2–ZrO2-PAN) composite ion exchanger was produced and its properties were examined by Fourier-transformed infrared spectroscopy, scanning electron microscopy, The BET (Brunauer, Emmett and Teller) surface area, X-Ray diffraction analysis and thermogravimetric analysis. The adsorption of Strontium (Sr) from solutions by MnO2–ZrO2-PAN composite was studied thru batch experiments. The distribution Coefficient of Sr (II) on the composite sorbent was investigated against pH, interaction time, and primary concentration ion. To study the kinetics of adsorption, Pseudo-first-order and Pseudo second-order adsorption kinetics were studied and the results revealed that adsorption kinetics better fit to the pseudo-second-order model. Three iso-temperature models, Langmuir, Freundlich, and Temkin were applied to fit the experimental results. Among those models, Langmuir revealed the most suitable one with minimum deviation. The created composite exhibited strong compatibility to the elimination of Y (III), Ni (II), Pb (II), and Co (II) from radioactive waste streams. On the other, it is evident from the data that the quantifiable extraction of Sr (II) ions from Zr (IV), Mo (VI), and La (III) is feasible. MnO2–ZrO2 Loaded with (PAN) Polymer was figured out to have high ion exchange capacity and thermal stability and selectivity for strontium

Adsorption and safe immobilization of Sr ions in modified zeolite matrices

Abstract In the present study, an Iranian natural zeolite (Sabzevar region) was evaluated as a natural adsorbent for the elimination and immobilization of strontium ions from an aqueous solution. For improving the adsorption efficiency of strontium ion, the zeolite surface was modified by the Schiff base ligand of bis (2-hydroxybenzaldehyde)1,2-diaminoethane (H2L). The natural zeolite and zeolite/H2L were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray fluorescence (XRF), BET and scanning electron microscope (SEM). Analysis of the natural zeolite showed that the zeolite is from the type of clinoptilolite and has a crystalline structure with the specific surface area 29.74 m2/g. The results showed that strontium adsorption onto modified zeolite increases compared to unmodified zeolite from 64.5% to 97.2% (at pH = 6). The effective parameters pH, adsorbent dosage, initial concentration of strontium ions, contact time, temperature, and interfering ions, were studied and optimized. The maximum adsorption efficiency was confirmed by modified zeolite and found to be 97.5% after 60 min of equilibrium time at pH 6, 0.05g as adsorbent dosage, and at 25 °C. Adsorption of strontium was confirmed by Langmuir model with maximum adsorption capacity of 10.31 mg/g. Kinetic studies showed that the adsorption of strontium ions on the adsorbent follows pseudo-second-order (PSO) model. Also, the thermodynamics of the adsorption process indicated that the adsorption of strontium on zeolite/H2L is an endothermic and spontaneous process, and the adsorption mechanism is a combination of physical and chemical adsorption. Finally, to manage the secondary waste generated from the adsorption process, strontium ions were immobilized in a zeolite structure. The results showed that the stabilization is well done with the thermal preparation process. After thermal treatment at 25–900 °C, modified zeolite satisfactorily retains strontium during back-exchange tests with NaCl solution. According to the results, the amount of strontium released from the adsorbent phase decreases from 52.6 to 1.6% with increasing heat treatment temperature