查看更多>>摘要：Toxic organic pollutants in wastewaters are becoming a worldwide problem, which threatens life on earth and prevents essential elements to sustain living organisms. Nitro compounds and organic dyes are the most common contaminants, which result in disturbing problems for human health and the environment. The application of heterogeneous nanocatalysts is one of the most efficient methods to overcome this challenge. In view of this, a novel nanocatalyst containing multi-walled carbon nanotubes (MWNTs), Kraft lignin, and Pd nanoparticles (NPs) was synthesized through a straightforward procedure. The synthesis of Pd NPs was performed using laser ablation, generating fine NPs without chemical agents and impurities. The morphology and structure of the prepared nanocomposite were studied by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron (XPS) and Raman spectroscopy. The efficiency of the as-prepared nanocatalyst in the reduction of methylene blue (MB), 4-nitrophenol (4-NP), and hexavalent chromium [Cr(VI)], was investigated in an aqueous solution using sodium borohydride (NaBH4) or formic acid (HCOOH) as the reducing agents. The progress of the reactions was monitored by UV-Vis spectroscopy. The catalyst can be easily removed from the reaction media by centrifugation and reused five times without any observable decrease in the catalytic activity. Overall, the performance of MWNT/KL reported herein alludes to the prodigious practical significance of this tunable support in real world scenarios such as nanocatalysis and wastewater remediation.
查看更多>>摘要：Pharmaceuticals and personal care products (PPCPs) are a class of compounds of increasing concern because they are widespread in the ecosystem and possibly have adverse effects on living organisms. However, PPCPs cannot be easily removed from water using typical wastewater treatment plants, owing to the fact that the existing infrastructure does not allow removal of such small molecules. Therefore, it is of a great importance to select the most appropriate and efficient method for the removal of PPCPs from water. This work provides a critical review of various methods presenting the potential to be applied for the removal from water of pharmaceuticals and personal care products. Several processes: adsorption, advanced oxidation processes (photodegradation, photocatalysis, ozonation, Fenton reaction, Wet Air Oxidation, ultraviolet radiation, hydrogen peroxide oxidation), and membrane based techniques (ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, membrane distillation) are analysed and their performance during removal of PPCP from water is compared. Moreover, summaries presenting the efficiency of various materials applied during each of the processes are provided. Finally, the advantages and disadvantages of each presented method are summarised and comprehensively discussed.
查看更多>>摘要：Electrocoagulation (EC) has been attracting increasing amounts of attention due to its ability to remove the pollutants in widespread wastewater. Chloride ions (Cl~-) are the most commonly used electrolyte in the EC process. However, the role of the reactive chlorine species (RCS) generated near the electrode is often being underemphasised. In this study, the experiments focused on the generation of RCS and its contribution to the removal of metronidazole (MNZ) during EC. The present findings demonstrated the presence of Cl· and CIO· near the anode in solution, which dominated the degradation of MNZ. The MNZ decomposition pathways was proposed based on the generation of intermediate products. The toxicity of MNZ and its main degradation products was evaluated by Toxicity Estimation Software Tool (TEST) model and most of intermediates were less toxic than MNZ. Furthermore, the flocs could adsorb part of MNZ by characterizing the flocs using SEM-EDS, FT-IR, XRD and XPS. The contribution ratio of the flocs adsorption and the RCS oxidation for removing MNZ were 57.30% and 41.70%, respectively. Response surface methodology (RSM) was applied to optimize the operation parameters. The present work reveals a new mechanism of EC and manifest good potential for removing antibiotics from chloride-containing wastewater.
查看更多>>摘要：Industrially applied coalescence filters, e.g. oil mist filters, usually consist of several filter layers in combination with a downstream support grid. While in the past the focus of research on coalescence filters has been e.g. on the filter media itself, information on the influence of support structures on pressure drop and entrainment is scarce. Recent studies on the influence of support structures on differential pressure and entrainment showed, that stainless-steel perforated sheets are particularly well suited for this purpose. Based on these findings, innovative 3D printed support structures with novel printed modifications, like conical holes instead of cylindrical holes or additional roofs above each hole, in comparison to the state-of-the-art stainless-steel perforated sheets, were developed and evaluated in this work. Especially for oleophilic filter media, where the oil film in quasi-steady state is build up on the filter rear side and thus, noticeably affected by support structures, the differential pressure was in some cases slightly reduced, whereas entrainment was significantly reduced (up to -75%) by the developed 3D printed support structures. For oleophobic filter media entrainment was mainly affected by the 3D printed support structures and was significantly reduced.
查看更多>>摘要：The main objective of this study was the design of an efficient adsorptive process to extract water from thin air, based on MIL-100(Fe), which is a promising material in water adsorption-related processes. Indeed, equilibrium and dynamic studies were performed to evaluate the suitability of this adsorbent. CO2, N2, and O2 adsorption equilibrium isotherms were measured at three different temperatures, and CO2 was the gas that presented a higher affinity towards MIL-100(Fe). H2O adsorption equilibrium isotherms follow a Type VI isotherm, showing two steps (0.21 < P/Po < 0.30 and 0.36 < P/Po < 0.40) attributed to the presence of two different cavities (25 and 29 A) on its structure. The obtained data were regressed against adsorption equilibrium isotherm models (Langmuir model, Dual Ising-Single Langmuir model, and Polanyi's potential theory). The H2O adsorption dynamic behavior was in agreement with the expected from the H2O vapor adsorption equilibrium isotherms. Furthermore, the dynamic adsorption behavior of water adsorption in fixed-bed experiments was well predicted by the developed model. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis revealed a high regeneration capability during the adsorption/desorption cycles. Additionally, the structure remains stable during the water vapor contact and after exposure at different temperatures. Temperature Swing Adsorption (TSA) process, with a column volume of 0.35 m~3, allowed maximum H2O productivity of 86.81 · day~(-1) for MIL-100(Fe).
查看更多>>摘要：Inversely removing trace CO2 from C2H2 and C2H4 by adsorbents has been considered as a promising energy-efficient alternative to traditional cryogenic distillation or chemisorption for the purification of C2H2 and C2H4. However, few adsorbents could realize one-step separation for CO2/C2H2 and CO2/C2H4 because of lack of specific recognition of CO2 and high separation selectivity as well as the similar molecular sizes and physical properties between CO2 and C2H2/C2H4. Herein, we selected the water-stable and easily scalable Bi-MOF(SU-lOl) as the adsorbent platform, which features ultramicropores and rich basic carbonyl oxygen sites and thus is expected to favor the CO2 adsorption. Al, In, and Ga ions were used to replace the Bi metal centers to tune the pore size and pore surface charge. The inversely selective capture characteristics of CO2 from C2H2 and C2H4 in SU-101(M) (M = Bi, In, Ga, and Al), both hydrated and activated, were theoretically investigated by grand canonical Monte Carlo simulations and density functional theory, highlighting the effects of coordinated water and metal centers. The results show that it is the synergistic effect of pore size limitation and carbonyl O charge regulation by coordinated water that leads to the special recognition of CO2 and the inverse CO2/C2H2 and CO2/C2H4 separation in hydrated SU-101 materials, compared to the activated counterparts. SU-101(Al) shows the highest selectivity for CO2/C2H2 (15.5) and CO2/C2H4 (8.3) under ambient conditions. Our work provides a general guidance for rational design of MOF adsorbents for the applications of separating CO2/C2H2 and CO2/C2H4 inversely.
查看更多>>摘要：With the over-exploitation of global resources, the recycling of gold becomes an urgent task to be solved. In this regard, design of stable adsorbents with low cost and large capacity is meaningful for the secondary utilization of resources. Herein, to obtain the efficient adsorbents, dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8) were cross-linked for the first time by Friedel-Crafts reaction to synthesize crown ether-based hypercrosslinked porous polymers, named DB18C6-HCP and DB24C8-HCP, respectively. These adsorbents exhibit high porosity, good stability, and outstanding gold adsorption selectivity. Notably, DB18C6-HCP exhibits a high gold uptake capacity with 1667 mg g~(-1). Furthermore, gold ions are in situ reduced into gold nanoparticles by DB18C6-HCP and DB24C8-HCP along with gold ion adsorption process. In short, we have confirmed the potential of porous organic polymers for the adsorption of gold, and provided a powerful reference for the recovery and reduction of gold.
Rafael L ZornittaLuis A.M. RuotoloLouis C.P.M. de Smet
10页
查看更多>>摘要：Capacitive deionization (CDI) is a technology used for water desalination and ion recoverybased on the use of capacitive electrodes. Typically, the porous carbon electrodes used for CDI display limited ion storage capacity and selectivity due to the mechanism of ion storage in the electric double layer, but impressive improvements have been achieved using alternative, redox-based electrode materials, including conducting polymers like polyaniline (PAni). PAni is capable of capturing anions based on redox chemistry, but it degrades at anodic potentials typically used in CDI. In this work, we employed a multi-channel membrane CDI cell to map the stability window of a porous carbon electrode modified with PAni by controlling the anodic potential. We demonstrated for the first time that applying a potential as low as + 0.35 V (vs. Ag/AgCl) yields a stable and high chloride removal capacity (65 mg_(Cl)/g_(Anode)) with charge and coulombic efficiencies close to 100% for CDI. Furthermore, this is first work to explore the selectivity of the PAni-modified CDI electrodes towards chloride in binary solutions, evidencing that chloride is preferred regardless the valence of the competing anions. We believe that this work provides an important contribution for a larger figure, one in which CDI can be used for both high-performance water desalination, and efficient anion-selective removal and recovery.
查看更多>>摘要：A braid-reinforced polybenzimidazole (PBI) hollow fiber membrane has been reported, which was made by our in-house developed spinning devices. The braid elements not only remarkably increase the mechanical strength of the PBI hollow fiber membrane to more than 100 Mpa but also maintains its low swelling ratio of less than 2% even in harsh organic solvents compared with the self-support PBI hollow fiber. The effects of PBI dope concentration, flow rate and wetting agents for braid co-extrusion on the structure and separation performance of braid-reinforced hollow fibers have been investigated. The spinneret design and the braid handling device are also discussed. The recently developed braid-reinforced PBI hollow fiber membrane has a rejection of Rose Bengal (RB) over 90% in methanol (MeOH) with a permeance up to 3.6 Lm~(-2)h~(-1)bar~(-1) compared with the self-support hollow fiber under high pressure. In addition, the braid-reinforced membrane has a slightly higher rejection and a stable separation performance over 40 h than the self-support one because the former has a lower swelling ratio than the latter one. Due to the favorable interfacial bonding between the PBI coating layer and the reinforced elements, the braid-reinforced PBI hollow fiber membrane can withstand an operation pressure of exceeding 10 bar, which exhibits its great prospects for solvent resistant nanofiltration (SRNF) applications.
查看更多>>摘要：The authors regret that in the above paper, Figs. 4(c, d, f), Fig. 7b, and Fig. 8a have some errors. Therefore, new analyses were provided as follows: In Fig. 4c, the O 1s spectrum indicates two peaks at 530.1 and 531.4 eV. The existence of Bi~(3+) was proved by the Bi 4f_(5/2) and Bi 4f_(7/2) peaks at binding energies of 164.7 and 159.4 eV, respectively (Fig. 4d).
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