Song-Dong Ding

Extraction of Trivalent Europium and Americium from Nitric Acid Solution with Bisdiglycolamides

Two bisdiglycolamides (BisDGAs) of N,N,N′′′,N′′′-tetrabutyl-Nʹ,N′′-ethidene bisdiglycolamide (TBE-BisDGA) and N,N,N′′′,N′′′-tetrabutyl-Nʹ,N′′-m-xylylene bisdiglycolamide (TBX-BisDGA) were synthesized. Their extraction behaviors of Eu(III) and Am(III), as well as nitric acid were investigated from nitric acid medium by using n-octanol as diluent. Nitric acid is extracted as the form of HNO3·(BisDGAs)0.6 by BisDGAs and the conditional acid uptake constants of TBE-BisDGA and TBX-BisDGA were 0.26 and 0.10, respectively. The distribution ratios of Eu(III) and Am(III) increased with the increase of nitric acid and extractant concentration, whilst decreased with temperature rise. TBX-BisDGA had a stronger extraction power for Eu(III) and Am(III) than TBE-BisDGA. Both of the extractants displayed a higher affinity toward Eu(III) than Am(III). In the examination of the acidity range from 0.5 to 5.0 M, a maximum separation factor SFEu(III)/Am(III) can reach 8.0 at 3.0 M HNO3 for TBX-BisDGA; and 10 at 4.0 M HNO3 for TBE-BisDGA, respectively. Slope analyses showed that Eu(III) and Am(III) are extracted as di-solvated species by TBX-BisDGA or TBE-BisDGA. The extraction mechanism was described and the apparent extraction equilibrium constant as well as Gibbs free energy change, enthalpy change and entropy change were presented. In addition, their Eu(III) complexes were analyzed by using infrared spectra.

Hydrolytic degradation behaviors of poly(p-dioxanone) in ambient environments

The effects of temperature and relative humidity on the hydrolytic degradation of poly(p-dioxanone) (PPDO) were investigated. The hydrolytic degradation behaviors were monitored by tracing the changes of water absorption, mechanical and crystalline properties, molecular weight and its distribution, surface morphologies, as well as infrared absorption peaks and hydrogen chemical shifts during the degradation. It is found that the water absorption increases whilst the intrinsic viscosity, tensile strength and elongation at break decrease as the temperature or relative humidity increases. With degradation time growing, the molecular weight drops and its distribution broadens. The crystallinity of PPDO has a tendency to increase at first and then to decrease, while the crystalline structure is not significantly changed. At the same time, some cracks are observed on the surface and keep growing and deepening. All results show that temperature plays more significant roles than relative humidity during the degradation. The analyses of Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy reveal that the degradation of PPDO is a predominant hydrolysis of ester linkages.

Non-isothermal Crystallization Behaviors of Poly(p-dioxanone) and Poly(p-dioxanone)-b-poly(butylene succinate) Multiblock Copolymer from Amorphous State

A novel alternating multiblock copolymer poly(p-dioxanone)-b-poly(butylene succinate) (PPDOBS) was prepared through a two-step process including the initial ring-opening polymerization of p-dioxanone (PDO) initiated by poly(butylene succinate)-diol and the following chain extension, using hexamethylene diisocyanate (HDI) as a chain extender. The resulting PPDOBS was characterized by hydrogen nuclear magnetic resonance spectroscopy (1H NMR), wide angle X-ray diffraction (WAXD), and differential scanning calorimeter (DSC). The WAXD analysis showed that the introduction of PBS segments did not change the crystal structure of PPDO. The heating scans of DSC curves showed that the cold crystallization temperature was decreased after the introduction of PBS segments, which indicated that the ability of PPDO to crystallize was improved. The non-isothermal crystallization kinetics of PPDO and PPDOBS were evaluated by means of Avrami, Ozawa, and Mo methods. It was found that the Ozawa method was not suitable to describe the crystallization kinetics for both PPDO and PPDOBS. The results of Avrami and Mo methods showed that crystallization rate of PPDO were enhanced by introduction of PBS segments. In addition, the activation energies for non-isothermal crystallization calculated using the Kissinger method for PPDO and PPDOBS were 46 kJ/mol and 38 kJ/mol, respectively, indicating the crystallization ability of PPDO was improved after the introduction of PBS segments.

Synthesis of Extraction Resin Containing N,N,N′,N′-Tetraisobutyl Diglycolamide and its Application for Separation of Sr(II) from Rb(I)

Abstract A novel Levextrel resin containing N,N,N′,N′-tetraisobutyl diglycolamide (TiBDGA) was synthesized by suspension polymerization of styrene and divinylbenzene and its performance for separation of Sr(II) from Rb(I) was investigated. The effects of crosslink degree, stirring speed, and the ratio of porogenic-agents on the resin synthesized were examined. The optimum TiBDGA resin with 40 wt.% divinylbenzene as cross linking agent and 20 wt.% of n-octanol as porogenic-agents provided excellent adsorption capacity of 22.5 mg/g. The distribution coefficient (K d) of Sr(II) in HNO3 media onto the resin depended heavily on the acidity in the aqueous solution. The maximum K d for Sr(II) (7300 mL/g) was observed when the HNO3 concentration in aqueous phase reached 2 mol/L. The difference in the Sr(II) and Rb(I) distribution coefficients of several orders of magnitude implied that 89Sr may be separated from 86Rb with a radionuclide purity greater than 99%. And the maximum static adsorption capacity of Sr(II) on the resin was 22.5 mg/g.

Influences of Bis-(2,6-Diisopropylphenyl) Carbodiimide on the Thermal Stability and Crystallization of Poly(P-Dioxanone)

ABSTRACT The influences on the thermal degradation and crystallization behaviors of poly(p-dioxanone) (PPDO) were initially investigated by adding bis-(2,6-diisopropylphenyl) carbodiimide (labeled as St). It was found that the addition of St could significantly enhance the thermal stability and crystallizability of PPDO. The thermal decomposition temperature of PPDO increased with the increase of the amount of St added. The thermal decomposition activation energies of PPDO increased from 94.2 to 130.8 kJ mol−1 in the case of 5 wt% St. The addition of St did not change the crystal structure of PPDO, while it increased the number of nucleation sites and improved the crystallizability of PPDO. The crystallization activation energies, calculated by the Kissinger method, for PPDO and PPDO/5 wt% St were −111.4 and −141.5 kJ mol−1, respectively, confirming the crystallizability of PPDO was enhanced after the addition of St.