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Selective separation of Nd from La/Ce/Pr using phosphate-based ionic liquids: Solvent extraction studies and density functional theory
No full textSince neodymium (Nd) has similar physicochemical properties to lanthanum (La), cerium (Ce) and praseodymium (Pr), their efficient separation and purification is very difficult. Three new phosphate-based ionic liquids (ILs): N,N-dimethyloctylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-8,N-H][DEHP]), N,N-dimethyldecylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-10,N-H][DEHP]), N,N-dimethyldodecylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-12,N-H] [DEHP]) were synthesized and evaluated for selective separation of Nd(III) from aqueous solution. The influences concentration of Nd(III), phase volume ratio (O/A), cation chain length of ILs, extraction time, extraction temperature, salt concentration, solution acidity have on the performance of ILs for extraction separation of Nd(III) from aqueous solution were systematically investigated. It was found that the extraction efficiency (E) of Nd(III) using [N-1,N-1,N-8,N-H][DEHP] was close to 100% at pH of 4, and that it only required 10 min to reach extraction equilibrium at 303 K. Meanwhile, the separation factors (beta) values of beta Nd/La, beta Nd/Ce, beta Nd/pr using [N-1,N-1,N-8,N-H][DEHP] were all higher than 3. The density functional theory (DFT) results indicated that the interaction between [N-1,N-1,N-8,N-H][DEHP] and Nd were stronger than that between La, Ce and Pr. In addition, almost 100% of Nd(III) could be recycled from the loaded [N-1,N-1,N-8,N-H][DEHP] phase using 0.16 mol center dot L-1 hydrochloric acid via one step, and the E of Nd(III) by regenerated [N-1,N-1,N-8,N-H][DEHP] remained about 97% after eight cycles. Moreover, the extraction mechanism of Nd(III) using [N-1,N-1,N-8,N-H][DEHP] was complexation mechanism based on infrared spectroscopy and slope analysis. This work furnishes a strategy for selective separation of Nd(III) using phosphate-based ILs without diluent
Ruthenium-catalyzed reductive amination of ketones with nitroarenes and nitriles
No full textThe Ru(dppbsa)-catalyzed reductive amination of ketones with nitroarenes and nitriles using H-2 as the environmentally benign hydrogen surrogate is developed in this study. Cross-experiments demonstrated that both reactions are initiated by the reduction of nitroarenes or nitriles to the corresponding amines, followed by condensation with ketones to give imines and thereafter hydrogenation. However, the route to the formation of an amino-ligated Ru complex during the reduction of nitroarenes or nitriles, followed by in situ nucleophilic C-N coupling, cannot be completely excluded. This newly developed versatile method features good functional group tolerance, which provides a novel design platform for homogeneous catalysts in constructing motifs of secondary amines
Sequential hydrogenation of nitroaromatics to alicyclic amines via highly-dispersed Ru-Pd nanoparticles anchored on air-exfoliated C3N4 nanosheets
No full textDeveloping efficient and green catalytic systems is highly desired in the syntheses of alicyclic amines via hydrogenation of nitroaromatics. Herein, we developed Ru-Pd dual active site catalysts in which Ru and Pd species were anchored and highly dispersed on air-exfoliated carbon nitride (Ru-Pd/C3N4-air). As-prepared catalysts were employed in the hydrogenation of nitrobenzene (NB) to cyclohexylamine (CHA). Compared with single Ru or Pd based catalysts, Ru-Pd dual active site catalysts obtained a higher CHA production rate of 26.7 mol CHA mol(-1) Ru center dot Pd h(-1) at 80 degrees C and 3 MPa H-2. The activation energy for the hydrogenation of the nitro group and benzene ring was calculated as 26.26 kJ mol(-1) and 66.30 kJ mol(-1), respectively. Intrinsic kinetic studies demonstrated that Pd was the dominant metal for hydrogenation of nitro group, while Ru was dominant for benzene ring. Thereinto, the corresponding non-dominant metals enhanced activation and dissociation of H-2, thereby improving catalytic activity significantly. This excellent performance of Ru-Pd catalysts could be attributed to highly dispersed Ru-N-x and Pd-N-x at a nanoscale distance, which was conducive to metal-assisted hydrogenation. Stability investigation showed that the performance of Ru-Pd catalysts could be essentially maintained at a high level. Additionally, the substrate scope could be successfully extended to hydrogenation of other nitroaromatics with different substituents
Schiff base nanoarchitectonics for supramolecular assembly of dipeptide as drug carriers
No full textDevelopment of peptide-based supramolecular materials with hierarchical morphology and tunable guest loading displays broad potential as drug carrier in view of biocompatibility and biodegradability. Herein, we report a facile Schiff base nanoarchitectonic for supramolecular assembly of diphenylalanine (FF) metastable gel. The addition of trace glutaraldehyde (GA)/H2O solution induces the Schiff base reaction between GA and FF accompanying by phase transition from gel to solution. FF nanoparticles and hierarchical beaded nanofibers with autofluorescence properties can be constructed by regulating the competitive assembly between FF-H2O and FF-GA oligomer. Moreover, various guest molecules with different hydrophilic and hydrophobic properties can be easily loaded into such assembled particles and its release can be triggered under weak alkaline conditions, which show the potential application of the assembled FF system as drug carriers. (c) 2022 Elsevier Inc. All rights reserved
special fund of Beijing Key Laboratory of Clean Fuels and Efficient Catalytic Emission Reduction Technology
No full textMajor Science and Tech- nology Program for Water Pollution Control and Treatment[2015ZX07205-003.]
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A review on facilitated transport membranes based on z-complexation for carbon dioxide separation
No full textThe emission of CO2 from human activities is the principal reason for global warming. Membrane separation technology has been extensively regarded as a tremendous potential option for mitigating CO2 emissions when utilizing fossil fuels as a major source of energy. As an important group of CO2 separation membranes, the fixed CO2 carrier-facilitated transport membrane guided by z-complexation reactions is a rising research field and has attracted much attention in the last ten years due to its desirable CO2 separation performance in the dry state and high resistance to oxidation. In this review, facilitated transport theories derived from z-complexation reactions are discussed for an in-depth understanding, rational design and tunable fabrication of facilitated transport membranes. According to the different fixation methods of metal ions (CO2 active carrier), polymer electrolyte membranes and mixed matrix membranes are discussed in detail as two strategies for fabricating CO2-facilitated transport membranes. Future perspectives toward z-complexation reaction-facilitated transport membranes are proposed