查看更多>>摘要：Transitional metal oxides with lamellar feature are desirable catalysts towards peroxydisulfate (PDS) activation for wastewater treatment. However, the feasibility and mechanism of PDS activation by Cu-Fe bimetallic nanosheets are barely explored. Herein, novel ultrathin Cu-Fe oxide nanosheets (CuFe-OS) were constructed by fast reduction for efficient PDS activation. Assembled by intercrossing nanosheets with about 4 nm thickness, Cu1Fe1-OS possessed regular crystal texture, multiple metal-oxygen bonds, and abundant oxygen vacancies, distinguishing from the amorphous Cu-Fe oxide (CuFe-O). Such features of Cu1Fe1-OS contributed to a 62.40 % increase of typical organic pollutant (acid orange 7) removal efficiency and 13.47 times improvement of degradation rate constant, compared to Cu1Fe1-O. Furthermore, the coupling function of radical and nonradical pathways drove the Cu1Fe1-OS activation process, with O-1(2) and O-center dot(2)- as the primary reactive oxygen species. The O-1(2) was principally generated from the recombination of O-center dot(2)-, manifesting the transformation from radical to nonradical mechanism in the Cu1Fe1-OS/PDS system. Abundant oxygen vacancies benefited the generation of O-center dot(2)- and the conversion of metallic ions. The bimetallic synergy in Cu1Fe1-OS boosted the reversible redox cycles of Fe3+/Fe2+ and Cu2+/Cu+. This work provides a novel strategy of persulfate activation for wastewater remediation and deepens the understanding of coupled radical and nonradical mechanisms.
查看更多>>摘要：Deep eutectic solvents (DESs) are a new class of solvents that can offset some of the major drawbacks of common solvents and ionic liquids. When dealing with the preparation of dense membranes, the use of DESs is still challenging due to their low compatibility with the polymer phase. In this research, a novel L-proline:sulfolane (molar ratio 1:2) DES was synthesized and used for the preparation of more sustainable bio-based membranes using chitosan (CS) as a polymer phase. The compatibility among both phases (polymer and DESs) and their ability to form homogenous membranes was preliminary studied. In this regard, scanning electron and confocal microscopies were used to completely map the structure of the resulting membranes evidencing a complete homogenous structure. The membranes were also characterized in terms of contact angle (CA), Fourier trans -formed infrared spectroscopy (FTIR), mechanical resistance and swelling degree (uptake). Preliminary perva-poration tests for the separation of a methanol (MeOH)-methyl tert-butyl ether (MTBE) azeotropic mixture were, thus, performed. In this regard, the addition of DESs provided an enhanced separation efficiency in comparison to pristine CS membranes. Thanks to the morphology and properties exhibited, the newly developed membranes can be considered as excellent bio-based candidates to be explored in other gas selective and solvent oriented membrane operations.
查看更多>>摘要：Flotation separation of smithsonite (ZnCO3) from calcite (CaCO3) is not commonly satisfied using traditional fatty acids, and thus, more selective collectors are required. In this regard, a new collector, N-hexadecanoylglycine (C16Gly) was used to selectively collect ZnCO3 from CaCO3 in this work. The flotation selectivity of C16Gly was predicted by DFT calculations. The calculation results showed that the C16Gly anion adsorbed on the ZnCO3/CaCO3 surface via two Zn-O/Ca-O bonds. Moreover, as the new Zn-O bonds were more covalent than Ca-O bonds, the adsorption of C16Gly on the ZnCO3 surface was more stable. Therefore, this collector may be used as a specific collector for ZnCO3 rather than for CaCO3. The DFT results were confirmed by experimental results. Single-mineral flotation and contact angle results both suggested that C16Gly efficiently floated ZnCO3 rather than CaCO3 at pH >= 10. As for the 1:1 ZnCO3 and CaCO3 mixture, the Zn recovery was much higher than that of CaO with 3 x 10(-4) mol/L of collector at pH 10, and the separation efficiency reached 64.53% under the same conditions. XPS analysis revealed that Zn/Ca atoms on ZnCO3/CaCO3 surface were involved in the reaction of C16Gly with the mineral surface. In addition, a good coverage of C16Gly on the ZnCO3 surface was observed by the time-of-flight secondary ion mass spectrometry system. In contrast, this collector was not found on the CaCO3 surface due to its poor adsorption capacity. These experimental results confirmed that C16Gly is a promising collector for the selective flotation of ZnCO3 from CaCO3 and DFT calculations are a powerful tool to predict the flotation behavior of C16Gly for the ZnCO3-CaCO3 system.
查看更多>>摘要：Walnut green husks are a good source of natural naphthoquinones (NQs). In this study, a novel extraction strategy combining microemulsion and high voltage electric discharge (HVED) was proposed to extract the NQs from walnut green husks and maximize the value of this agro-byproduct. Firstly, the optimum microemulsion formula (ME8) for NQs extraction was determined among 17 microemulsions prepared with various contents ratios. Then the single factor experiments were conducted to explore the effect of discharge parameters (voltage, treatment time, liquid-solid ratio) on NQs yield. These parameters were further optimized by response surface methodology with Box-Behnken design, and the highest yield of NQs (67.1 +/- 0.3 mg/g) was obtained under the predicted optimal conditions. The combination of HVED and microemulsion showed favorable synergistic preponderance and the NQs yield was 1.52 times higher than heating reflux extraction. Moreover, this strategy presented a competitive option to extract hydrophobic compounds in a less-organics-consumption way.
Eslami, TourajJakob, Leo A.Satzer, PeterEbner, Gerald...
9页
查看更多>>摘要：Traditional chromatographic purification steps consist of long loading steps at a constant residence time, especially during early stages of the downstream process. The breakthrough behavior of the product is usually well defined. This information can be used to optimize the loading phase by starting the loading phase at a low residence time and gradually increasing the residence time to boost productivity and resin utilization. Process modeling of the loading of lysozyme on a Toyopearl SP-650C stationary phase, a strong cation exchanger, revealed optimal residence time gradients. These gradients result in a faster breakthrough in the time domain, while having the same breakthrough as constant residence time loading, in the volume domain. Modeling also revealed that a delayed start of the gradient further increases productivity. Eventually, several mathematical optimizations were employed to ensure the optimality of the idea. We confirmed the process model results in lab experiments using lysozyme breakthrough in ion-exchange chromatography and monoclonal antibody breakthrough in protein A affinity chromatography. Productivity of the loading step could be increased by 68 % from 40.8 to 68.7 g L(-1)h(-1) resin for protein A chromatography while retaining the same breakthrough behavior and better manufacturability of unstable proteins. Consequently, the bound fraction of protein is maintained above 99 %. This affords similar productivity gains as multicolumn chromatography while employing an easy-to-implement process model that can be used on conventional systems.
查看更多>>摘要：Desulfurization by ore pulp has proved to be an attractive pathway, by which sulfur dioxide (SO2) removal from fuel gas and mineral acid leaching can be realized simultaneously in hydrometallurgy. However, the weak reaction between alkalescent ore pulp and the weak acid SO2 aqueous solution, and large mass transfer resistance caused by the heterogeneity of pulp seriously impeded their applications. Increasing the dispersion and surface tension of pulp by surfactants is an effective way, which has been rarely reported. Herein, the influence of the representative cationic, anionic and nonionic surfactants on desulfurization performance by ore pulp containing electrolytic manganese residue (EMR), phosphate ores (PO), and copper tailings (CT) were investigated systematically. Due to the high performance of anionic surfactant in enhancing the dispersion of ore pulp, reducing the surface tension of pulp, and increasing foaming, the desulfurization efficiency of EMR, PO, and CT was increased by 21.56 +/- 3.25%, 23.13 +/- 4.09%, and 20.54 +/- 1.01%, respectively. However, the charge neutralization of cationic surfactant and the non-dissociation of nonionic surfactant made their promotion lower than the anionic one. Further, the co-ions and counter-ions in pulp affected the performance of surfactants in desulfurization. Besides, transition metal ions catalyzed the oxidation of SO2 and promoted the formation of H2SO4.
查看更多>>摘要：Basicity is an intrinsic factor of coagulants that plays important roles in turbidity removal. However, the effects of basicity on the coagulation performance of titanium (Ti) coagulants remain unclear. This knowledge gap is mainly due to the lack of highly polymerized Ti coagulants. In this study, we fabricated a series of Ti-based coagulants with basicity values in the range of 0-93% and evaluated their coagulation performance with simulated and real waters of low-turbidity. A positive correlation was observed between the basicity of the Ti coagulants and the coagulation performance, i.e., higher basicity led to higher turbidity removal, larger floc size, and faster settling rate. For the two titanium xerogel coagulants (TXC) of similar chemical structures, the one with a higher basicity (TXC-93%) worked better than the one of a lower basicity (TXC-78%). The advantage brought from the difference in basicity is of great significance in the purification of low-turbidity water. For the treatment of a surface river water, the required dosage of TXC-93% was about 1/2 to 1/3 of those of titanium tetrachloride (TiCl4) and polytitanium tetrachloride (PTC-21%), and was comparable to that of a high-quality commercialized polyaluminum chloride (PAC-72%). The results here provide a useful technical guidance for the mass production and application of Ti coagulants.
查看更多>>摘要：Efficient separation and reclaim of HCl from its effluent gases is vital for its high value resource utilization. For this, six choline chloride (ChCl) based deep eutectic solvents (DESs) were designed and synthesized. Their absorption behavior for HCl gas was studied at varying temperature and pressure, and analyzed in terms of their free volume, hydrogen bond donors (HBDs)' structure, interaction energy, various instrumental characterization, and changes of viscosity and density in the absorption process. The dissolution mechanism of HCl was proposed, and a new 3-parameter physical chemical absorption model (PCAM) was developed. The solubility of HCl in DESs is reversely proportional to the interaction energy between ChCl and HBD, and followed the order of ChClpolyol (ethylene glycol (EG), glycerol) > ChCl-hydroxyacid (glycolic acid, lactic acid) > ChCl-carboxylic acid (oxalic acid, malonic acid). ChCl-EG (1:2) is the best solvent here for its lowest viscosity (similar to 33.18 mPa.s), and highest absorption capacity of 0.97 mol.mol- 1 (0.403 g.g(-1)) at 303.15 K and 101.3 kPa. The interaction energy of ChCl-EG (1:2) (-95.99 kJ.mol(-1)) is comparable to its interaction energy with HCl (-54.68 kJ.mol(-1)), which promotes the complete desorption of HCl under mild conditions compared to the partial desorption from its neat constituents. DES is proved to be a viable solvent for HCl gas absorption in terms of its least volatility, low cost and energy consumption, and high efficiency and reversibility.
查看更多>>摘要：Solar-driven membrane distillation is an emerging desalination technology with low energy consumption and efficient vapor collection, but the low vapor flux and limited efficiency hinders its practical application. Here, we demonstrated an innovative photothermal composite membrane by depositing polypyrrole nanotubes (PPy NTs) as functional coating layer onto an electrospun poly (vinylidene fluoride) (PVDF) nanofibrous support layer via vacuum filtration stabilized by adhesive polydimethylsiloxane (PDMS). According to the proportional relationship between the fibrous materials diameter and the pore size, the large-scale surface gaps between adjacent nanofibrous could be replaced by smaller pores from the PPy NTs layer on the PVDF substrate. The PDMS with low surface energy was used as an adhesive to in-situ solder the loose PPy NTs together as well as to enhance the adhesion between the PPy layer and the PVDF substrate to form an integrated and robust dual-layer composite membrane with superhydrophobicity, high porosity and controllable pore size. By exploring the optimal match of PPy loading and PDMS concentration, the solar-to-thermal performance and structural stability could be significantly improved. With 1 sun irradiation, the selected composite membrane thus showed a high-water vapor flux of 1.3 kg/(m(2).h) and a photothermal conversion efficiency of 81.6%, specially, the membranes maintained stable permeate conductivity during the 10 h solar-driven DCMD seawater desalination test. These results indicated that the photothermal dual-layer superhydrophobic composite membranes has promising potential for desalination with the help of sustainable energy sources such as sunlight.
NSTL
Elsevier