Recovery of deuterium from hydrogen–deuterium mixture using palladium

The applicability of palladium for the separation of hydrogen isotopes (hydrogen and deuterium) is evaluated systematically by generating isotherm data and conducting column experiments in a laboratory set-up. Effect of various parameters such as concentration of the isotopic mixture, particle size, eluent flow rate, etc. is studied experimentally. A fixed-bed chromatographic model is developed and validated using the experimental data. The model is further used to predict the performance of a multi-column configuration for large-scale separation. Chromatographic separation is thus found to be a promising technique to achieve the required purity and hence it may be clubbed with the existing systems (e.g. cryogenic distillation) to obtain enhanced performance.     

Solvent-induced generation of two cadmium-based metal–organic frameworks from 1, 3, 5-benzenetricarboxylic acid ligand

Two cadmium-based metal–organic frameworks (MOFs), namely [Cd₅(BTC)₄(DMAc)₂(H₂O)₂DMF]·2[H₂N(CH₃)₂]·4DMAc (JUC-133) and [Cd₃(BTC)₂(DMSO)₄] (JUC-134) (JUC = Jilin University, China), based on 1, 3, 5-benzenetricarboxylic acid ligand (H₃BTC) were synthesized by solvent-induced strategy under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, luminescent spectroscopy, TGA analysis, and powder X-ray diffraction. The ligand is connected to cadmium metals to form different cores with distinctive coordination modes to generate different structures. JUC-133 displays a new three-dimensional (3D) topology with the point symbol (4·6²)₄(4·8²)₄(4²·6⁵·8³)₄(8⁶) based on Cd₂(COO)₅ and Cd₂(COO)₄ as secondary building units (SBUs), which is unknown in previously reported MOFs. JUC-134 can be symbolized as a rutile (rtl) topology with the point symbol (4·6²)₂(4²·6¹⁰·8³) based on Cd₃(COO)₆ as SBUs. Furthermore, the luminescent of the ligand H₃BTC and compounds were measured at room temperature. It is worth noting that the solvent could play an important role in the structural assembly process.     

Graphene supported Ru@Co core–shell nanoparticles as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane and methylamine borane

Well-dispersed graphene supported Ru@Co core–shell nanoparticles were synthesized by one-step in situ co-reduction of aqueous solution of ruthenium(III) chloride hydrate, cobalt(II) chloride hexahydrate and graphite oxide (GO) with ammonia borane under ambient condition. The as-synthesized nanoparticles exert excellent catalytic activities, with the turnover frequency (TOF) value of 344 mol H₂ min^− 1 (mol Ru)^− 1 for catalytic hydrolysis of ammonia borane, which is the second highest value ever reported. The as-synthesized catalysts exert superior catalytic activities than the monometallic (Ru/graphene), alloy (RuCo/graphene), and graphene-free Ru@Co counterparts towards the hydrolytic dehydrogenation of AB. Moreover, the catalytic hydrolysis of MeAB at room temperature was also studied. These Ru@Co NPs are a promising catalyst for amine-borane hydrolysis and for developing a highly efficient hydrogen storage system for fuel cell applications.     

Application of ZnO–NiO greenly synthesized nanocomposite adsorbent on the elimination of organic dye from aqueous solutions: Kinetics and equilibrium

Organic dyes are discharged into aquatic systems from several industries causing severe environmental problems and toxicity to aquatic life. Therefore, it should be removed from water with a suitable process. Among several treatment processes, adsorption is one of the most attractive because of its simplicity, efficiency, and low operating cost. Moreover, adsorption supports environmental sustainability if a suitable adsorbent is used. In this work, a green route was followed to prepare ZnO: NiO nanocomposites using the Neem leaf extract as a stabilizing agent instead of harmful chemicals. Four different samples with three different ZnO:NiO ratios were prepared, namely: 3Z:1 N, 1Z:1 N, 1Z:3 N and 1Z:1 N without extract. The samples were characterized by XRD, TEM, SEM, IR, and UV, which all confirmed the successful synthesis of the nanocomposites. The nanocomposites were used for the adsorption of methyl orange (MO) from aqueous solutions. The four nanocomposites prepared with the aid of the extract showed a high sensitivity with 100% removal of MO from 6.25 ppm solutions. Furthermore, all the samples have a relatively fast kinetic with an equilibrium time less than 1 h. Also, the three samples maintained 100% removal efficiency after 5 adsorption-desorption cycles. The difference in particle size distribution obtained for the 1Z:1 N prepared with and without the extract confirms the important rule of the extract as a capping agent with an average size of 18 nm for the sample with the extract and 88 nm for the sample prepared without the extract. This difference in the particle sizes has been reflected on the adsorption performance of the two samples with a maximum adsorption capacity of 33 mg/g for the sample prepared with the extract compared to 6 mg/g for the sample without the extract.     

Excellent field emission characteristics from few-layer graphene–carbon nanotube hybrids synthesized using radio frequency hydrogen plasma sputtering deposition

The growth of few-layer graphene (FLG) on carbon nanotubes (CNTs) was realized by using radio frequency hydrogen plasma sputtering deposition. A defect nucleation mechanism and a two dimensional growth model of the FLG were proposed, and field emission characteristics of these FLG–CNT hybrids were studied. They show excellent field emission properties, with a low turn-on electric field (0.98 V/μm) and threshold field (1.51 V/μm), large field enhancement factor (～3980) and good stability behavior, which are much better than those of the as-grown CNT arrays. The sharp edges and the low work function of the hybrids are believed to be responsible for the improved field emission properties.     

3-D pillared clay mimics of lanthanide–organic frameworks constructed from 5-fluoroisophthalic acid and 4,4′-bipyridine through hydrogen bonds

Four 2-D lanthanide coordination polymers constructed from 5-fluoroisophthalic acid show reliable 3-D pillared clay mimics based on the secondary hydrogen-bonding with 4,4′-bipyridine templates. The dimensionality of the structures turns out to be independent of the ionic radius of the lanthanide centers and the Eu^III complex displays strong red luminescence.     

Photocatalytic hydrogen production from methanol aqueous solution under visible-light using Cu/S–TiO2 prepared by electroless plating method

Cu was loaded on the S-doped TiO₂ by electroless plating method. The prepared Cu/S–TiO₂ exhibited high photocatalytic activity for hydrogen generation, and the yield is up to 7.5 mmol h^− 1 g^− 1cat in methanol solution. Their physical structure and chemical properties were characterized by UV–Vis, XRD, XPS and EXAFS. The copper species were CuO and Cu₂O, and the sample showed excellent visible light absorption ability. Comparing with the sample prepared by chemical reducing method, the electroless plated copper on S–TiO₂ was highly dispersed, which could facilitate photo-generated charges capture, transfer and separation.     

Solvent-induced generation of two magnesium-based metal–organic frameworks with doubly inter-penetrated ReO3 nets constructed from the same linkers but distinct inorganic nodes

Through changing the components of solvent, two Mg-based metal–organic frameworks were synthesized, which possess the same two-fold interpenetrated ReO₃ net constructed by identical linkers, 4,4′,4″-benzene-1,3,5-triyl-tribenzoate, but distinct nodes, Mg₂ and Mg₆ units, respectively. Here, DMSO and water are key factors for forming hexanuclear clusters, while DMF and DMSO act as template reagents for constructing super-octahedral cavities.     

Preparation,characterization and photocatalytic activity of a novel nanostructure composite film derived from nanopowder TiO2 and sol–gel process using organic dispersant

A novel sol–gel-derived titanium dioxide nanostructure composite has been prepared by spin-coating and investigated for the purpose of producing films. The processing of the composite sol–gel photocatalysts involved utilizing of precalcinated nanopowder titanium dioxide as filler mixed with sol and heat treated. The sol solution was prepared by adding titanium tetra isopropoxide (Ti(OPr)₄ or TTP) to a mixture of ethanol and HCl 35.5% (mole ratio TTP:HCl:EtOH:H₂O = 1:1.1:10:10), then a solution of 2 wt% methylcellulose was added and stirred at room temperature. Precalcinated TiO₂ nanopowder was dispersed in the sol and the prepared mixture was deposited on the microscope glass slide by spin-coating. The inhomogeneity problem in preparation of composite film which causes peeling off and cracking after calcination due to the shrinkage of the films with thermal treatment were overcome by using methylcellulose (MC) as a dispersant. The composite heat treated at approximately 500 °C has the greatest hardness value. Surface morphology of composite deposits by scanning electron microscopy (SEM) showed remarkable increase in the composite surface area. Evaluation of the adhesion and bonding strength between the coating and substrate was carried out by the scratch test technique. The minimum load which caused the complete coating removal, for composite thick film was 200 g/mm² which indicates a strong bond to the substrate. Photocatalytic activity of the composite film was evaluated through the degradation of a textile dye, Light Yellow X6G (C.I. Reactive Yellow 2) as a model pollutant and were compared with those of similar composite thick film without MC, thin film of TiO₂ and TiO₂ nanopowder. The results show that the photocatalytic activity and stability of the composite films are higher than those of nanopowder TiO₂. However, a remarkable increase in the composite surface and good mechanical integrity make this composite film a viable alternative for commercial applications.