查看更多>>摘要：In this study, a floral and lamellar interlaced double Z-scheme ternary heterojunction Bi2O2CO3/g-C3N4/Bi2O3 was prepared by a simple precipitation and acalcination methods. TEM images demonstrated the flower-like layered structures of 3D Bi2O2CO3 and Bi2O3 were interwoven with the 2D g-CsN4 block structures. The synthesized heterostructure indicated the enhanced photocatalytic performance in tetracycline (TC) degradation compared with single Bi2O2CO3, Bi2O3 and g-CsN4 under simulated solar irradiation. Besides, organic pollutants including ciprofloxacin (CIP), methylene blue (MB), and rhodamine B (Rh B) were further used to evaluate the photocatalytic activity of Bi2O2CO3/g-C3N4/Bi2O3. The effects of pH, supporting electrolyte on photocatalytic performance were also investigated. Furthermore, the possible pathways of TC degradation intermediates were reasonably deduced by liquid mass spectrometry (LC-MS), and the toxicity analysis were evaluated based on quantitative structure activity relationship (QSAR) and structure of warning. Finally, according to free radical trapping experiments a double Z-scheme photocatalysis mechanism was proposed.
查看更多>>摘要：Herein, the alkynyl groups are grafted on g-C3N4 via ball milling of g-C3N4 and CaC2. The successful function-alization of g-C3N4 by alkynyl is demonstrated by Fourier transform infrared spectroscopy and X-ray photo-electron spectroscopy. Ultrathin wrinkle-like structure with abundant pores is observed for the resulted alkynyl functionalized g-C3N4 nanosheets, which can furnish abundant photocatalytic active sites. The photocatalytic NH3 production rate of 0.12 mmol-g_(cat)~(-1)·h~(-1) is gained for alkynyl functionalized g-C3N4 under UV-visible irradiation, which is 2.0-folds higher than pristine g-C3N4 (0.058 mmol-g_(cat)~(-1)·h~(-1)). A maximum of 1.9 and 1.5 folds enhancements are achieved for the photodegradation of rhodamine B and levofloxacin over functionalized g-C3N4 compared to pristine g-C3N4. The improved mechanism is investigated by linear sweep voltammetry, transient photo-current, Tafel plots, electrochemical impedance spectroscopy, Mott-Schottky curves, turnover frequency, transient decay time, photoluminescence spectra, etc. The modification technique proposed in this paper can also be adopted to prepare other alkynyl functionalized semiconductors for photocatalytic application.
查看更多>>摘要：Biocatalytic membranes, which are fabricated by taking advantage of the synergetic effect of membranes and enzymes, have been one of the attractive treatment methods as sustainable and environmentally friendly. In biocatalytic membrane systems, enzymes can be free or immobilized, but the number of immobilized applications increases due to tire advantages of immobilization. Immobilization is one of the critical points to improve the storage and operational stability of enzymes. Additionally, immobilized enzymes have a significant benefit over free enzymes in terms of reusability. This review summarizes recent advances in the preparation of biocatalytic membranes with the different immobilization methods of enzymes in/on membranes, paying particular attention to recent approaches for anti-fouling and emerging pollutant degradation applications. Also, some future outlooks were briefly presented.
查看更多>>摘要：Superhydrophilic/superhydrophobic surfaces with unique superiority have been applied for oil-water separation over a long time. Facing the increasingly complicated requirements in diverse separation fields, developing intelligent surfaces with switchable superhydrophilic/superhydrophobic properties are highly needed. In this work, versatile and robust poly(ionic liquid) (PIL) coatings were designed and a series of intelligent materials with switchable superwettabilities were generated for high-efficient oil-water separation. The PIL coatings were obtained by polymerization of PIL monomer on the roughened GO sheets, for which were realized by the immobilization of Fe3O4 nanoparticles. Three materials with different structures (cotton fabric (CF), nylon fabric (NF) and cotton ball (CB)) were chosen as the coating substrates. After ''dip-coating'' process, the PIL coated materials (PCMs) exhibited switchable superhydrophilic/superhydrophobic performances due to the anion-responsive behavior of PIL and the roughness enhanced effect. Thus, the PCMs showed high-efficient separation performances upon multiple oil-water separation cycles, and the separation could be switched between ''water-removing'' and ''oil-removing'' by anion exchange. Meanwhile, the PIL@CF had high permeate fluxes, which could separate layered water-oil mixtures rapidly under gravity; the PIL@NF had the highest separation efficiency; the PIL@CB possessed great potential to be used as efficient absorbents for water/oil adsorption and recycle.
查看更多>>摘要：To control NO_x (nitrogen oxide) emitted from point-of-use (POU) scrubbers during semiconductor production, O3 was injected into the inlet of a wet scrubber to oxidize NO to NO2, and Na2S, Na2SO3, and Na2S2O3 were added to remove N02 in the scrubber. Although Na2S is superior to the other reducing agents, it generated H2S below pH 11. Therefore, NaOH was added to adjust the pH, rapidly increasing Na2S consumption up to 7.13 times the theoretical consumption. In order to reduce chemical consumption, we manufactured a novel wet scrubber in which the liquid reservoir and scrubbing zone were separated according to the chemical. The novel scrubber dramatically reduced the consumption of Na2S and NaOH to levels below 1.42 and 1.19 times the theoretical values. Although Na2SO3 and Na2S2O3 do not generate H2S, their NO_x removal performances were inferior to Na2S. Hence, when Na2SO3 and Na2S2O3 were used alone as reducing agents, the chemical consumption rates were 38 times and 95 times their theoretical values, respectively. In order to reduce the chemical consumption rate, we mixed Na2SO3 and Na2S2O3 to prevent fast depletion of Na2SO3 by the free-radical scavenger reactions of thiosulfate (S2O3~(2-)). The total chemical consumption rates depending on the mixing ratio of Na2SO3 and Na2S2O3 were experimentally evaluated. Finally, an optimal mixing ratio of 1:1 was determined, which corresponded to a consumption rate of only double the theoretical value.
查看更多>>摘要：4',4'(5'')-Di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) modified with dodecyl benzenesulfonic acid (DBS) and 1-dodecanol was impregnated into silica-based polymer support (SiO2-P). The stability of adsorbent was evaluated according to thermal decomposition and leakage property. The leakage of total organic carbon (TOC) and dodecyl benzenesulfonic acid from the adsorbent was approximately constant and was below 2.26 wt % at 298 K at 0.5-7 M HNO3. The O 1s and Sr 3p XPS spectra of the adsorbent after adsorption of Sr(II), suggesting that strong binding interaction of Sr(II) and oxygen in DtBuCH18C6. The adsorbent containing DBS promoted the adsorption of Sr(II) compared to the DBS-free one, demonstrating the DBS worked as a counter ion. By adsorption kinetic and isotherm analyses, linear driving force expression with external mass coefficient (K_(fa)) and Freundlich model was found to be appropriate for the accurate description of adsorption dynamics. The separation column was designed by numerical thermal analysis and simulating breakthrough curve based on the short column data. Mathematical adsorption dynamics model was built, thereby obtaining the breakthrough curve of scale-up column. Thermal analysis was conducted due to the large heat value per unit adsorbent volume of 2292.877 W/m~3. The effect of column length and diameter on breakthrough curve and temperature field was further computationally discussed. Thus, a preliminary design for Sr(II) processing column (Φ150 mm × H700 mm, breakthrough time: 9.55 h, processing volume: 76.92 dm~3/cycle) from high-level liquid waste was proposed.
查看更多>>摘要：In this study, the effect of pH and oxidant dosage on the removal rate of levofloxacin (LEVO) was investigated using potassium ferrate (Fe(VI)) as an oxidant, and the degradation kinetics of LEVO was studied accordingly. CuS, as a catalyst, was subsequently used to activate Fe(VI) for LEVO degradation. The experimental results showed that the degradation rate of LEVO by Fe(VI) accords with the second-order kinetic equation. The more Fe (VI) dosage or the lower the pH value, the faster the degradation rate of Fe(VI) to LEVO. In addition, CuS could significantly improve the Fe(VI)-mediated degradation of LEVO; the Fe(VI)-CuS system achieved a removal rate of 96.9% in 30 s (which was only 24.8% in Fe(VI) system). Then, the surface characteristics of fresh and used CuS were analyzed by scanning electron microscope, Brunauer-Emmett-Teller, X-ray diffraction and X-ray photo-electron spectroscopy. Subsequentiy, under similar experimental conditions, different systems were established to investigate the effects of Cu~(2+) and S~(2+) leached from CuS in Fe(VI)-CuS system. Furthermore, the radical scavengers and methyl phenyl sulfoxide probe experiments proved that Fe(V)/Fe(IV) rather than radicals play a key role in the Fe(VI)-CuS system. The reaction mechanism of CuS catalyzing Fe(VI)-mediated degradation of LEVO can be summarized as follows: Fe(VI) adsorbed on the active site oxidizes the ionic bond of CuS to form Cu~(2+) and S~(2+); as an electron donor, S2'' can promote the adsorbed Fe(VI) to produce more Fe(V)/Fe(IV), thus accelerating the degradation of LEVO in Fe(VI)-CuS system. Meanwhile, the leached Cu~(2+) and LEVO formed an organic complex Cu-LEVO, which is easily degraded by Fe(VI)/Fe(V)/Fe(IV) in the system. Finally, three possible degradation pathways were proposed based on 10 intermediates identified by Q-TOF LC/MS. This study provides the experimental data and theoretical support for the treatment of LEVO-containing wastewater using Fe(VI) and Fe(VI)-CuS systems.
查看更多>>摘要：Considering the highly toxic by-products generation and environmental friendliness, the adsorption process is a suitable solution as the end of pipe treatment for refractory organics in coking wastewater. Nitrogen-doped micro-mesoporous carbon prepared by carbonization and KOH activation of urea-formaldehyde resin (UFCA) realized effective adsorption of quinoline, phenol and pyridine in coking wastewater. Among them, UFCA-900 has large specific surface area (Sbet = 1469.94 m2 g_1) and excellent adsorption properties: the adsorption removal rate of quinoline reached 98.40% about 16 min, and the maximum adsorption capacity of quinoline was 721.90 mg-g-1 at 318 K, the adsorption capacity of phenol and pyridine at 298 K were 341.59 mg-g-1 and 225.08 mg-g-1, respectively. The adsorption kinetics of UFCA-900 obeyed the pseudo-second-order model, and the adsorption process was endothermic. The membrane adsorption reactor demonstrated efficient adsorption, well separation, and negligibly irreversible membrane fouling. The adsorption mechanism included electrostatic interactions, k-k interactions and hydrogen bonds. Regeneration test proved that the removal rate of the chemically regenerated UFCA-900 was similar to the fresh adsorbent after six cycles. Taken together, a simple strategy for tn-situ nitrogen-doped porous carbon has been developed and the resultant composite UFCA-900 has promising application prospect in coking wastewater treatment.
查看更多>>摘要：The novel poly(m-phenylene isophthalamide) (PMIA) ultrafiltration membrane with enhanced anti-fouling performance was successfully designed using amphiphilic block copolymer Pluronic F127 via non-solvent induced phase separation (NIPS) technique combined with induced segregation. The influences of Pluronic F127 on PMIA membrane's microstructure and properties were systematically conducted by employing a series of characterized methods. Meanwhile, the density functional theory (DFT) calculation was employed to study the intermolecular force among the bulk PMIA, Pluronic F127 additive, solvent, and inorganic agent. Results demonstrated that Pluronic F127, functioning as both a porogen and an induced-segregation additive, could effectively affect membrane structure and property. Specifically, the resultant membrane morphologies of the sublayer gradually altered from the finger-like pore to cavity-like shape, and the pore diameter and porosity displayed a stepwise upward trend via increasing the concentration of Pluronic F127, which further induced the loss of the membrane's mechanical strength. The filtration experiments demonstrated that the water permeation was enhanced, along with the slightly reduced rejection to bovine serum albumin (BSA) with the increasing concentration of Pluronic F127. Furthermore, the fouling resistance and stability were improved remarkably, which benefited from the enhanced hydrophilicity caused by the migration of polyethylene glycol (PEO) segment of Pluronic F127 toward membrane surface and inner-pore wall. Additionally, DFT calculation confirmed the interaction energy among the dope components, which provided theoretical support on the dope design. In summary, the Pluronic F127/PMIA ultrafiltration membrane demonstrated great potential in the field of water purification and wastewater reclamation.
查看更多>>摘要：A noble metal-free photocatalyst, the porous flower spherical Ni5P4 coupled g-CsN4 quantum dots (GCNQDs) was prepared by a simple ultrasonic impregnation method for the degradation of norfloxacin in wastewater. The GCNQDs exhibit obvious quantum confining effect due to its small particle size. For Ni5P4, its large specific surface area is conducive to the adhesion of GCNQDs, so that GCNQDs/Ni5P4 composite photocatalysts have excellent photocatalytic performance. In addition, the important role of porous NisP4 in promoting electron-hole separation and photocatalytic performance was confirmed by experiments and density functional theory (DFT) calculations. It was found that the GCNQDs and Ni5P4 formed a Shottky junction. At the same time, the GCNQDs/ NisP4 composite photocatalysts showed good stability in the cycle test, which made it become a kind of green, efficient and repeatable photocatalytic material. This work proposed the degradation mechanism of GCNQDs/8% Ni5P4 composite photocatalysts and the possible degradation path of norfloxacin, providing a new idea for the design of highly active composite photocatalysts.
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