Ruthenium Nitrosyl Structure in Solvent Extraction Systems: A Comparison of Tributyl Phosphate, Tetrabutyl Urea, N-Methyl, N-Octyl Ethylhexanamide, and N,N,N′,N′-Tetraoctyl Diglycolamide

Comparative Study of Callistemon citrinus (Bottlebrush) and Punica granatum (Pomegranate) Extracts for Sustainable Synthesis of Silver Nanoparticles and Their Oral Antimicrobial Efficacy

A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant's type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20-70 nm, and with 10-30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant's biomolecules on the nanoparticles' properties.

Structural Investigation of Technetium Dibutylphosphate Species Using X-ray Absorption Fine Structure Spectroscopy

The speciation of Tc after the extraction of Tc(IV) from H2O and 1 M HNO3 by dibutylphosphoric acid (HDBP) in dodecane has been studied by X-ray absorption fine structure (XAFS) spectroscopy. Results show the formation of dimeric species with Tc2O2 and Tc2O units, and the formulas [Tc2O2(DBP·HDBP)4] (1) and [Tc2O(NO3)2(DBP)2(DBP·HDBP)2] (2) were, respectively, proposed for the species extracted from H2O and 1 M HNO3. The interatomic Tc-Tc distances found in the Tc2O2 and Tc2O units [2.55(3) and 3.57(4) Å, respectively] are similar to the ones found in Tc(IV) dinuclear species. It is likely that the speciation of Tc(IV) in dodecane is due to the extraction of a species with a Tc2O unit for (2) and to the redissolution of a Tc(IV)-DBP solid for (1). The XAFS results for (1) and (2) were compared to that obtained for the extraction of Tc(IV) with TBP/HDBP/dodecane from 0.5 M HNO3, (3) which highlight the formation of Tc mononuclear nitrate species {i.e., [Tc(NO3)3(DBP)] or [Tc(NO3)2(DBP·HDBP)]}. These results confirm the importance of the preparation and speciation of the Tc(IV) aqueous solutions prior to extraction and how much this influences and drives the final Tc speciation in organic extraction. These studies outline the complexity of Tc separation chemistry and provide insights into the behavior of Tc during the reprocessing of used nuclear fuel.

Separation of Radioactive Ruthenium from Alkaline Solution: A Solvent Extraction and Detailed Mechanistic Approach

A solvent extraction-based technique has been utilized to study the separation of ruthenium from simulated alkaline solution using Aliquat 336 as the extractant and isodecyl alcohol (IDA) as the phase modifier in n-dodecane. The effects of various experimental parameters such as solution pH, mixing time, concentration of Aliquat 336 and IDA, role of citric acid as the aqueous phase modifier/complexing agent, and stripping agents have been evaluated. It was observed that with the increase in the solution pH, the extraction efficiency increases gradually. However, when citric acid was added into the aqueous solution, an overall increase (from ∼20 to 91%) in ruthenium extraction is observed. 20 min of the mixing time was found to be sufficient to reach the extraction equilibrium. Solution composition was optimized as 50% Aliquat 336 and 10% IDA in n-dodecane (v/v) for maximum extraction. The stripping of ruthenium from the loaded organic phase has been studied using HCl and HNO₃. The result indicates that in the presence of 8 M HNO₃, ∼73% of ruthenium can be back extracted to the aqueous phase in a single contact. The stripping efficiency of HNO₃ was found to be higher than that of HCl. Active studies with ¹⁰⁶Ru as the radiotracer were also performed and monitored using a HPGe detector. The same method was implemented for extraction studies with real waste solution in the presence of other radionuclides such as ¹³⁷Cs, ⁹⁰Sr, and ¹²⁵Sb. The presence of the chemical species in aqueous as well as organic phase has been identified using UV-vis spectrophotometry, Fourier transform infrared spectroscopy, and Raman spectroscopy. Density functional theory-based quantum mechanical calculations have been performed in order to unravel the extraction mechanism with the present solvent system.

Selective actinide(III) separation using 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl]pyridine (PyTri-Diol) in the innovative-SANEX process: laboratory scale counter current centrifugal contactor demonstration

An innovative-SANEX process for the selective separation of the trivalent actinides americium and curium from a simulated PUREX raffinate solution was successfully demonstrated on the laboratory scale using a 16-stage 1 cm annular centrifugal contactor setup. The solvent was composed of 0.2 mol L−1 N,N,N′,N′-tetra-n-octyl-diglycolamide (TODGA) and 5% v/v 1-octanol in a kerosene diluent. Zr(IV) and Pd(II) co-extraction was prevented using trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA) as a masking agent in the feed. The actinide(III) selective back-extraction was achieved using 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl]pyridine (PyTri-Diol) in 0.45 mol L−1 HNO3 as a CHON alternative to the sulfur-containing stripping agent used in a previous version of the innovative-SANEX process. The new process described in this paper showed excellent performance for the recovery of An(III). An An(III) product with a quasi-quantitative recovery of americium and curium (≥99.9%) and very good separation from fission and activation products was obtained (decontamination factors ≥4000). Only a slight contamination with Zr and Ru was observed. This test demonstrates the successful use of molecules containing only carbon, hydrogen, oxygen, and nitrogen atoms (so-called CHON molecules) for the selective separation of An(III) from a simulated PUREX raffinate solution. By avoiding sulfur- or phosphorous-containing molecules, the generation of secondary radioactive waste during process operation can be reduced drastically.

Density functional theory investigations on the coordination of Pa(v) with N,N-dialkylamide

The density functional theory (DFT) method was used to study the coordination of a series of N,N-dialkylamides with Pa(v) to shed light on the inherent principles for screening amide extractants of Pa(v) from aqueous solution.