Sorption of some radionuclides from liquid waste solutions using anionic clay hydrotalcite sorbent

¹²⁹I and ⁷⁹Se are potentially important anionic radionuclides in safety assessments due to their high mobility, radiotoxicity, and long half life's (1.7 × 10⁷ and 3.27 × 10⁵ years, respectively). This study is interested in the sorption of ¹³¹I and ⁷⁵Se radionuclides onto magnesium iron hydrotalcite (Mg/Fe HTlc). Mg/Fe HTlc was prepared by co-precipitation technique and characterized using different analytical tools such as FT-IR, XRD, XRF, TGA & DTA, SEM, and BET. Results obtained from this study showed that the adsorption process was a very fast equilibrium time (20 min). The distribution coefficient values as a function of pH have high separation factors for ¹³¹I at all different pHs. Reaction kinetic obeys the pseudo-second-order model. Maximum sorption capacity for ¹³¹I and ⁷⁵Se has the values 21.45, and 9.25 mg/g respectively. Sorption isotherms are more relevant to a Langmuir isotherm. The % removal of ¹³¹I is decreased by increasing the concentration of competing species. The investigation evidenced that the prepared sorbent is suitable for the removal of ¹³¹I and ⁷⁵Se from radioactive waste and could be considered potential material for purification of effluent polluted with these radionuclides.

Comparison of the physical and thermodynamic stability of amorphous azelnidipine and its coamorphous phase with piperazine

The thermodynamic stabilities of an amorphous phase and a coamorphous phase of azelnidipine in 0.01 M HCl medium were investigated using a solution chemistry method.

Pharmaceutical cocrystals, salts and polymorphs: Advanced characterization techniques

The main goal of a novel drug development is to obtain it with optimal physiochemical, pharmaceutical and biological properties. Pharmaceutical companies and scientists modify active pharmaceutical ingredients (APIs), which often are cocrystals, salts or carefully selected polymorphs, to improve the properties of a parent drug. To find the best form of a drug, various advanced characterization methods should be used. In this review, we have described such analytical methods, dedicated to solid drug forms. Thus, diffraction, spectroscopic, thermal and also pharmaceutical characterization methods are discussed. They all are necessary to study a solid API in its intrinsic complexity from bulk down to the molecular level, gain information on its structure, properties, purity and possible transformations, and make the characterization efficient, comprehensive and complete. Furthermore, these methods can be used to monitor and investigate physical processes, involved in the drug development, in situ and in real time. The main aim of this paper is to gather information on the current advancements in the analytical methods and highlight their pharmaceutical relevance.

Solid state characterization of azelnidipine-oxalic acid co-crystal and co-amorphous complexes: The effect of different azelnidipine polymorphs

In present study, based on the two polymorphs (α and β form) of azelnidipine (AZE), 12 complexes of AZE and oxalic acid (OXA) were prepared by solvent-assisted grinding (SG) and neat powder grinding (NG) methods at the AZE/OXA molar ratios of 2:1, 1:1, and 1:2. The effect of the different polymorphs of AZE on the micro-structure of the complexes were investigated by powder X-ray diffraction (PXRD), tempreture modulated differential scanning calorimetry and thermogravimetric analysis, cryo-field emission scanning electron microscope system, fourier transform infrared (FTIR), and solid-state nuclear magnetic resonance spectroscopy. β-AZE-OXA co-crystal was produced at β-AZE/OXA molar ratio of 2:1 when SG method was used; while α-AZE was used to produce α-AZE-OXA co-crystal at same condition. However, the other 10 combinations were in co-amorphous forms, including the NG samples with α (or β)-AZE/OXA molar ratios of 2:1, 1:1 (SG and NG), and 1:2 (SG and NG). Although the XRD pattern and IR spectra of the two co-crystals showed no difference, the melting enthalpy and specific heat c_p of the β-AZE-OXA co-crystal was higher than that of the α-AZE-OXA co-crystal, indicating that the numbers of solvent molecules which entered the two co-crystal lattices were different. Interestingly, obvious difference occurred in the IR spectra between the α-AZE-OXA and β-AZE-OXA co-amorphous systems. 1745cm^-1 wave-numbers, which were assigned to the free CO groups, appeared in the α-AZE-OXA co-amorphous systems even when just a small amount of OXA was introduced, thereby indicating the presence of different intermolecular forces in the two series of co-amorphous forms. The solubility in different media and the dissolution rate in 0.1molL^-1 HCl of the 12 complexes were determined. The dramatically improved dissolution rates of the α- and β-AZE-OXA 1:2 (NG) combinations in vitro showed potential in improving the physicochemical properties of AZE by co-amorphous complex formation.