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Nanostructure titanium carbide MXene (Ti3C2Tx) was modified with KH2PO4 and chitosan to effectively remove strontium from nuclear wastewater. Nuclear waste includes radionuclides of uranium, thorium, strontium, and cesium, which are classified depending on the concentration of radionuclides. Nuclear waste with a high strontium concentration is the production waste of radiopharmaceutical production centers. Ti3C2Tx was synthesized from Ti3AlC2 using HF40% and HF in situ (MILD-Ti3C2Tx) in 24 h at 313.15 and 333.15 K. Morphology, structure, and functional groups were investigated using the XRD, SEM, EDS, FTIR, and BET analyses. The Sr(II)'s adsorption capacity on Ti3C2Tx-HF and Ti3C2Tx-HF in situ was obtained as 61.9 and 253.5 mg g−1, respectively (temperature, 298.15 K; pH, 7.00; contact time, 180 min; and Sr(II) concentration, 150 mg l−1). Ti3C2Tx-HF in situ showed fourfold adsorption due to more hydroxyl functional groups and larger interlayer spacing. Ti3C2Tx was modified with KH2PO4 and chitosan to investigate the mechanism of change of Sr(II)'s adsorption capacity, which increased to 370 and 284 mg g−1, respectively. The structural results of modified Ti3C2Tx showed that the surface functional groups increased when modified with chitosan. In addition, modification with KH2PO4, through encapsulating large amounts of KH2PO4 between Ti3C2Tx layers, increased the possibility of Sr(II) diffusion between layers and electrochemical interactions with hydroxyl groups, and thus, increased its adsorption. Some experiments were designed to investigate the effect of parameters like initial concentration of Sr(II), contact time, temperature, and pH solution, as well as modified- and unmodified-Ti3C2Tx on adsorbent. The results revealed that the adsorption process of Sr(II) with pristine and modified-Ti3C2Tx follows pseudo-second-order kinetics and Freundlich heterogeneous isotherm model. Freundlich model isotherm indicates the presence of various functional groups on the surface and between the pristine and modified Ti3C2Tx layers. Electrostatic reactions and intra-sphere complexation were the two dominant mechanisms of the adsorption process. [ABSTRACT FROM AUTHOR]

To improve the mechanical properties, the cobalt ferrocyanide precipitation was carried out on clinoptilolite as an inorganic polymer. In this work the combination of two important factors, stability (zeolite) and high adsorption capacity (cobalt ferrocyanide) were considered to improve the ions uptake ability of adsorbent. The modification was approved by X-ray diffraction, Scanning electronic microscopy and Fourier transform infrared spectroscopy. The modified zeolite was applied to remove Sr(II) and Cs(I) ions from aqueous solution in a batch system. The adsorption capacities of modified zeolite for Cs(I) and Sr(II) improved to 90 and 130 mgg-1, respectively. The Sr(II) and Cs(I) removal were investigated as a function of shaking time, pH, Sr(II), and Cs(I) initial concentration and temperature. The experimental data were fitted well to Langmuir isotherm model for two sorbet metal ions. The time dependence sorption data showed that the uptakes of Cs(I) and Sr(II) were very rapid and apparent sorption equilibriums were achieved within 100 min of contact time. The kinetic experimental data were fitted to the pseudo-first order, pseudo-second order, the double exponential, Elovich and intraparticle diffusion models. The sorption rates and capacities as well as rate constants were evaluated.

To carry out our research, C6CoFeN6@poly-1-naphthol nanoparticles were synthesized and characterized by SEM, X-ray diffraction, Fourier transform infrared, thermogravimetric analysis and Brunauer-Emmett-Teller (BET) analyses. The SEM images indicate that the average particle sizes are about 60 nm in diameter. The BET result provides a clear evidence for the high surface area of the sample 180.6 m2/g. Cs(I) ions removed from the aqueous solution in a batch mode using CoHCF@poly-1-nanphtol as an adsorbent. The adsorption effecting parameters such as the solution pH, initial Cs(I) concentration, contact time and temperature were studied. Maximum sorption capacity for the nanocomposite was found to be 200.5 mg/g at 1000 mg/g, pH = 5 and 298 K. The time-adsorption dependence studies indicated that the maximum Cs(I) uptake was within the initial 40 min contact time and the adsorption mechanism was governed by the double exponential model. The equilibrium sorption data fitted well to the Freudlich model with n ˃ 1 indicating a stronger interaction and high affinity of C6CoFeN6@poly-1-naphthol for Cs(I) ions. The thermodynamic parameters, including changes in Gibbs free energy, entropy and enthalpy, were determined. The results indicated that CoHCF-poly-1-nanphtol could be a potential adsorbent for the uptake of Cs(I) ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

A new FeIIISnIISnIVH[P(MoO)]· xHO nano-hybrid was synthesized by chemical co-precipitation. The product was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. From TEM images, the size of the product was estimated to be smaller than 30 nm. The adsorption efficiency of the obtained hybrids were determined for Sr(II) and Th(IV) ions. The kinetics and thermodynamic of metal ions were studied. Results explained that the pseudo second-order sorption mechanism is predominant and the sorption of each ion is an endothermic process. [ABSTRACT FROM AUTHOR]