查看更多>>摘要：The solvent extraction of Pd2+ in nitric acid solution by a phenanthroline-derived diamide ligand of N,N '-diethylN,N '-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) and the complexation between them were described. By using meta-nitrobenzotrifluoride (F-3) as a diluent, Et-Tol-DAPhen ligand extracted Pd2+ with strong extractability and excellent selectivity in comparison with traditional amine extractants Aliquat 336 nitrate and tri-n-octylamine. Job's method and mole ratio method suggested the formation of a 1:1 complex of Pd2+ with Et-Tol-DAPhen. The extraction was a spontaneous and exothermic process of decreased entropy. Furthermore, the analyses of Fourier transform infrared spectra (FT-IR), UV-vis titration, and single-crystal X-ray diffraction revealed that the composition of the extracted species was [Et-Tol-DAPhen.Pd(NO3)2]. Based on the results of solvent extraction and complexation study, a neutral complexation extraction model was proposed. Meanwhile, the stability constant for the complexation of Pd2+ with Et-Tol-DAPhen was also presented.
Garcia-Costa, Alicia L.Carbajo, JaimeQuintanilla, AsuncionYuste-Cordoba, Francisco J....
7页
查看更多>>摘要：This work explores the feasibility of Fenton oxidation and Catalytic Wet Peroxide Oxidation (CWPO) at high temperature for the treatment of a complex cork-boiling wastewater (CBW) characterized by a high organic load (COD = 4906 mg/L) and substantial content of phenolics. Since CBW leaves the process at 100 degrees C, working at high temperature favors the integration of an on-site thermal water treatment, as explored in this work. Fenton oxidation of CBW at 100 degrees C employing 100 mg/L Fe2+ and the stoichiometric dose of H2O2 for complete mineralization (H2O2 = 9795 mg/L), yielded around 70% TOC removal after 180 min reaction. In CWPO, four different catalysts were tested, 0.5wt.%Fe/SiC, 4wt.%Fe/SiC, AC (activated carbon) and 4wt.%Fe/AC also at 100 degrees C. The Fe catalysts exhibited significant activity that makes possible the disposal of the treated water to the environment. Nonetheless, the occurrence of significant iron leaching jeopardizes their stability and the process implementation. On the contrary , AC showed a great stability as evidenced by the well maintained COD and TOC removal efficiencies of 78 and 58%, respectively, in a long term run (72 h) at 100 degrees C. Based on these results, CWPO at 100 degrees C using AC as catalyst can be considered a promising alternative for the integration of an on-site CBW treatment.
查看更多>>摘要：As an important raw material to produce many useful chemicals, cyclohexanol production attracts much attention to obtain high purity product, leading to high energy consumption. Traditional technologies include three routes: oxidation of cyclohexane, hydrogenation of phenol and direct hydration of cyclohexene. Without the risk of explosion and having a low price of raw material, the direct hydration of the cyclohexene route is selected in this paper. Four processes with different phase-refluxed or with/without a stripper configuration for the direct hydration of cyclohexene are investigated, including aqueous-phase-refluxed conventional reactive distillation (ACRD), an organic-phase-refluxed conventional reactive distillation (OCRD), an aqueous-phaserefluxed reactive distillation with a stripper (ARDS), and an Organic-phase-refluxed reactive distillation with a stripper (ORDS). The results show that the conventional reactive distillation (ACRD and OCRD) has a relatively low capital cost but has high operating costs due to high energy consumption, while the ARDS and ORDS show better performance than the OCRD and ACRD, but still have considerably high energy consumption. The ORDS shows better performance due to a slightly higher conversion of cyclohexene to cyclohexanol and the potential to achieve the better performance in terms of energy and economic considerations. Integration of a novel confirmation with heat pump assisted reactive distillation (HPRD) is investigated to further improve the energy efficiency and thereby reduce CO2 emission. The results show that the HPRD process realizes a significant energy saving of 58% and achieves 62% and 24% reductions in specific CO2 emission and total annualized cost, respectively, compared to ORDS, demonstrating high feasibility and environmental sustainability.
查看更多>>摘要：The forecast of an increase in the consumption of petroleum products, together with the growing scarcity of new deposits, makes it necessary to take full advantage of existing ones. The main problem faced by the petrochemical industry is high acid crude oils, which produce corrosion in equipment and high monetary losses. Crude oil acidity is usually calculated by making use of the total acid number (TAN). Current operations for the elimination of naphthenic acid (NA) have several drawbacks so at present this has led to new lines of research, among which the application of ionic liquids (ILs) in the extraction of this compound stands out. In this work, the extractive behavior of 6 different ILs has been analyzed with simulations of molecular dynamics (MD), a technique based on classical mechanics that allows visualizing the movement of molecules while they interact. This allows us to study the extraction mechanism of NA by ILs, as well as transport properties such as diffusion coefficients. In addition, it will be experimented in the laboratory with the same cases to contrast the results obtained, making use of a synthetic crude oil (SC, 150 g/mol, TAN equal to 3.8), which was treated with every IL at four different temperatures (30, 70, 90 and 120 degrees C). The IL/NA ratio implemented was 1:1 mol/mol, which corresponded more or less with the IL/crude ratio of 0.015 g/g. To support (MD) results and experimental results, the COSMO-RS model was used to characterize ILs analyzing the results obtained by the sigma-profile. COSMO-Therm was put into practice to study the theoretical predictions of the TAN in the liquid/liquid phase equilibria where results were in agreement with the experimental ones except for acetate, whose extraction mechanism is supposed to be different (neutralization). Computer simulation suggests that a longer alkyl chain of [BMIm] respect [EMIm] behaves better in extraction, and it seems that the anion plays a major role in the extraction process of the NA than the cation of the ILs. This tendency has been correlated with the experimental results.
查看更多>>摘要：In the design air filtration materials, surface modification and porosity control are appealing strategies to achieve a higher quality factor. In this study, a sacrificial template method was introduced to obtain hierarchically metal-organic framework (MOF)-loaded micro/nano-backbone fibrous filters. Cobalt carbonate hydroxide hydrate nanoneedle arrays were first grown on polyester fabric as a sacrificial template that provide Co2+ source for constructing a ZIF-67 on micro/nano fibrous backbone substrate, which resulted in a combination of enokitake-like and bead-on-string-like structure simultaneously. This unique structure effectively reduced the pore size of the fabric and provided a modified surface with a maximum exposure of MOFs. As a consequence, the composite fabric filter exhibited excellent PM2.5 removal efficiency of 97.5 +/- 1.2%, while with only a small increase in pressure drop (similar to 14 Pa). Particularly, the PM2.5 filtration quality factor was up to 0.051, which is 200% higher than that of pristine PET. Furthermore, the composite fabric filter showed excellent antibacterial activity against both S. aureus and E. coli. This study facilitated the design of hierarchically MOF-loaded fibrous filter materials with excellent comprehensive filtration performance.
查看更多>>摘要：The recovery of silicon from metallurgical-grade silicon refined slag (MGSRS) is of great significance for improving the utilization of silicon resources and increasing production profits. Currently, the main treatment method of MGSRS is crushing and manual selection. However, this method is characterized by the low recovery rate of silicon and lower production efficiency. In this study, a novel investigation was conducted to overcome these disadvantages and explore the separation behaviors of silicon from MGSRS. Moreover, direct remelting and electromagnetic induction remelting was conducted to determine why it is difficult to completely separate the slag and silicon in MGSRS, and to study the behaviors of silicon in different remelting methods. The results indicate that silicon is subject to the weak resultant force of gravity and buoyancy, which makes it difficult to move under the constraint of viscous force during direct remelting, and ultimately leads to the failure of separation from the MGSRS. On the contrary, under electromagnetic induction remelting conditions, silicon will aggregate to the center of the electromagnetic field to form bulk silicon, which can be separated from MGSRS. Ultimately, the results of this research confirm that electromagnetic induction remelting is a feasible alternative for the recovery of silicon from MGSRS. This study provides a new concept for the recovery of silicon from MGSRS, and is conducive to the development of related technologies in the future.
查看更多>>摘要：In the preparation of Sb-SnO2 internal layer of PbO2 electrode, the traditional thermal decomposition method has many problems, such as environmental pollution, short service life and low catalytic activity. Herein, a three-dimensional (3D) Sb doped SnO2 nanoflowers interlayer with good conductivity was prepared on the titanium substrate by the hydrothermal strategy to fabricate a novel PbO2 electrode (Ti/Sb-SnO(2)NFs/PbO2). Compared to the traditional PbO2 anode, a more compact and undulating 3D morphology of Ti/Sb-SnO(2)NFs/PbO2 electrode exhibited a higher total and inner active sites and stronger center dot OH generation ability. Specifically, three typical organics, methylene blue (MB), norfloxacin (NOR) and p-dihydroxybenzene (p-DHB), were effectively degraded by the novel Ti/Sb-SnO(2)NFs/PbO2 electrode with economic energy consumption and the degradation mechanism of MB was also investigated. This 3D interlayer also improved the anode stability and safety with the lifetime prolonged about 2.70 times (from 30.1 h to 81.3 h). Consequently, this work offers a meaningful method to prepare PbO2 anode with high catalytic activity and good stability for wastewater treatment.
查看更多>>摘要：With the rapid development of nuclear medical imaging, the production of Mo-99 has attracted much attention, because the important medical isotope Tc-99m can be obtained from Mo-99. N,N'-diethyl-N,N'-ditolyl-2,9-diamidel,10-phenanthroline (Et-Tol-DAPhen) has been proven to be an excellent ligand for the extraction of U (VI), while there are still few reports on the extraction of Mo(VI) using this ligand. To investigate the coordination structures of MoO22+ with Et-Tol-DAPhen, we carried out theoretical calculations using scalar relativistic density functional theory (DFT). The analyses of Wiberg indices (WBIs), quantum theory of atoms in molecules (QTAIM) and natural orbitals of chemical valence (NOCV) indicate that the MoO22+ have stronger complexation ability with O atoms compared to N atoms. The bonds between MoO22+ ions and ligands are mainly ionic interactions. The analyses of EDA and the most negative binding energy indicates that complex [MoO2L(NO3)](+) is energetically favorable and Et-Tol-DAPhen has also good extraction ability for MoO22+. Moreover, although both the electron-donating and electron-withdrawing groups have slightly effect on the electronic structures of the [MoO2L(NO3)](+) complexes, Et-Tol-DAPhen modified by the electron-donating group can enhance the extraction ability of MoO22+. This study is helpful to understand the complexation behavior of Et-Tol-DAPhen with MoO22+ and provides useful structural and thermodynamic information for the MoO22+ extraction with phenanthroline derivative ligands.
查看更多>>摘要：The pervaporative desalination of synthetic seawater and brines was studied to explore the water flux and salt rejection of a thin-film composite (TFC) membrane made of polydimethylsiloxane (PDMS) dip-coated on porous polysulfone support. Despite the hydrophobic nature of rubbery PDMS, we demonstrate that nonporous TFC membranes exhibit remarkable pervaporative desalination performance as evidenced by very high water permeance and 99.8 +/- 0.2% NaCl rejection. For comparison, two commercial hydrophilic polyamide thin-film composite membranes designed for reverse osmosis (RO) were also tested in pervaporation mode. At the highest temperature explored (85 degrees C) the PDMS thin-film composite membrane produced an outstanding pure water flux of -70 kg m- 2 h-1, which was 2.6 times higher than that of the best commercial RO membrane tested in this work. Although the presence of salt in the feed water reduced water flux to 36 kg m- 2 h-1 (at a brine sodium chloride concentration of 70,000 ppm and 85 degrees C), the hydrophobic PDMS composite membrane performed among the best compared with previously reported hydrophilic TFC polymer membranes.
查看更多>>摘要：Dust removal experiments of rare earth tungsten cathode tubular electrostatic precipitators (ESPs) were carried out at high temperatures from 1073 to 1373 K. The impact of various factors on dust collection efficiency was investigated. The results show that at temperature of 1173 K and working voltage of 4000 V, the dust collection efficiency of La-W cathode single tube ESP can reach 98.22% on coal-fired power plant flying ash. Compared with the single tube ESP, the dust collection efficiency of a double tube ESP is improved. Although the tubular rare earth tungsten cathode high-temperature ESPs have higher collection efficiency for particles greater than 5 mu m, they can't collect fine particles smaller than 5 mu m efficiently due to the limitation of their maximum working voltage. With rise of working voltage or temperature, the collection efficiency mainly shows evident increase tendency, while a little decrease with increasing temperature at higher temperature and lower voltage. Larger anode tube presents lower collection efficiency. Higher dust concentration leads to lower dust collection efficiency due to particle accumulation and deposition on the cathode surface. At low voltage (<3500 V), the dust collection efficiency can be significantly enhanced by extending the rare earth tungsten cathode.
NSTL
Elsevier