查看更多>>摘要：In this study, carbamazepine (CBZ) degradation was evaluated by peroxymonosulfate (PMS) activation after the simultaneous introduction of FeS2 and WS2. For FeS2/WS2/PMS system, 99% of CBZ was removed within 40 min under the conditions of 100 mg/L FeS2,150 mg/L WS2, 0.2 mM PMS, and initial pH 6.7. The apparent rate constant (k_(obs)) of CBZ degradation in the FeS2/WS2/PMS system (0.108 min~(-1)) was about 3.0- and 13.5-folds of that in FeS^PMS system (0.036 min~(-1)) and WS2/PMS system (0.008 min~(-1)). Quenching experiments and electron paramagnetic resonance (EPR) experiments indicated that hydroxyl radical, sulfate radical, superoxide radical, and singlet oxygen participated in the CBZ degradation. The catalytic reaction mechanism was proposed, and W on the surface of WS2 was the main reactive site to accelerate the regeneration of Fe(II) in the FeS2, which played a dominant role in PMS activation. The degradation pathways of CBZ in the FeS2/WS2/PMS system were put forward, and the ecotoxicity of CBZ and its degradation by-products was evaluated. A distinguishing performance of CBZ degradation in the successive six runs was shown. The work indicated the FeS2/WS2/PMS system was an efficient advanced oxidation process with promising engineering application due to its simple operation, high efficiency, and stability for the degradation of the organics from water.
查看更多>>摘要：Two new donor-acceptor covalent triazine polymers (CTPs), namely Th-Trz (JOU-6) and Th-Ph-Trz (JOU-7), containing electron-donating thieno[2,3-b]thiophene (Th) units and electron-withdrawing triazine (Trz) units have been successfully constructed (Ph = benzene ring). The unique conjugated structure of the CTPs invokes wide absorption range and high charge transfer efficiency. Because of these advantages, the as-prepared CTPs are highly effective photo catalysts for Cr(VI) reduction. It is found that high acid concentration in the photocatalytic system may assist the protonation of triazine groups in CTPs, which not only can enhance their adsorption ability for Cr2O7~(2-), but also can promote their charge transfer ability. Another important finding is that compared with JOU-6, JOU-7 shows more efficient charge separation owing to the introduction of benzene ring between the donor and acceptor units, inducing a spatial separation of photogenerated electrons and holes, and thereby giving a better photocatalytic performance. The spatial charge distribution of the CTPs was also investigated by theoretical calculation based on molecular orbital theory. Fascinatingly, Cr(VI) and organic pollutions can be simultaneously removed by JOU-7 without any sacrificial agents, oxidizer, or acid. This work provides a valuable strategy for the design and construction of effective photo catalysts for the removal of pollutants in wastewater.
查看更多>>摘要：Piezocatalysis has received tremendous interest due to the catalytic effect can be triggered by mechanical vibration. Herein, (1 - x)Bi_(0.5)Na_(0.5)TiO3-xBiFeO3 solid solution piezocatalysts were synthesized by a sol-gel method aim to improve the piezocatalytic activities of Bi_(0.5)Na_(0.5)TiO3 (BNT) and BiFeO3 (BFO). The piezocatalytic efficiencies of all obtained solid solution catalysts were improved compared with pure BNT and BFO for methyl orange (MO) degradation as expected. Among them, 0.5BNT-0.5BFO catalyst exhibited outstanding piezocatalytic activity and reusability, the reaction rate constant (0.0615 min~(-1)) was about 5.2 and 3.2 times larger than that of BNT and BFO. Trapping experiments demonstrated that ·O2~-and ·OH were the main species for MO degradation. Electrochemical measurements indicated that 0.5BNT-0.5BFO exhibited more efficient charge separation efficiency than that of BNT and BFO, which accounts for its efficient catalytic performance. A possible piezocatalytic reaction mechanism was proposed based on band structure and reactive oxygen species (ROS) detection. This work provides a new perspective for designing highly efficient piezocatalysts.
查看更多>>摘要：In this study, polyvinyl chloride (PVC) microplastic was removed by dielectric barrier discharge (DBD) plasma. The removal performance, mechanisms and products were studied. The results show that PVC removal efficiency reached to 85.9% at the optimal condition with 100 min treatment time. Discharge voltage and water content had significant influence on PVC removal efficiency. The removal mechanisms were studied by experiments and density functional theory (DFT) calculations, e_(aq)~-, was the most powerful reactive substance for PVC removal. ·OH and ~1H played both positive and negative roles in PVC removal. ·OH and ·H can capture e_(aq)~-, which was not beneficial for PVC removal, but they also reacted with PVC to carry out dehydrogenation and dechloridation reactions. Moreover, charge density difference unveiled that the electron transfer from PVC to "OH and "H to PVC. O2~(·-) played a negative role in PVC removal by consuming e_(aq)~-. The possible degradation pathway of PVC was proposed, and -CH site of PVC was the most important reaction site.
查看更多>>摘要：The separation of racemic drugs remains significance and challenge for pharmaceutical production. Recently, chiral drugs permeation separation based on membrane is a promising technology with advantages of energy efficient, continuous operation and cost-effectiveness. Herein, ethylenediamine-β-cyclodextrin (EDA-β-CD) mixed matrix membranes (EDA-β-CD MMMs) and EDA-P-CD modified graphene oxide thin-film nanocomposite membranes (GO/EDA-β-CD TFNMs) were fabricated via precipitation phase inversion and interfacial polymerization process, respectively. The corresponding membrane structure and GO nanosheets were characterized by SEM, TEM, ATR FT-IR, EA. Subsequently, the water flux, BSA rejection and stability of the membranes were studied. Moreover, enantioseparation performances of GO/EDA-β-CD TFNMs and EDA-β-CD MMMs toward (DL)-tryptophan (Trp) and (RS)-propranolol (Prop) were examined. Results showed that the GO/EDA-β-CD TFNMs exhibited extraordinary enantioselectivity, which remained high percent enantiomeric excess (ee.%) of Trp (100.00%) and Prop (75.34%). GO nanosheets with a multilayer structure and an interlayer spacing not only provided bonding site of EDA-β-CD but also improved permeation flux of the membrane. Finally, molecular docking technology was used to study the separation mechanism of the membranes. These findings demonstrate that GO/EDA-β-CD TFNMs might possess possibilities of high permeability and high enantioselectivity for chiral drugs separation.
查看更多>>摘要：This study employed a self-designed underwater arc discharge (UAD) plasma reactor, which combined advanced oxidation process (Fe2O3-CoFe2O4/PMS) and low-temperature plasma technology to efficiently degrade refractory organic pollutants (i.e. phenol, p-chlorophenol, p-nitrochlorobenzene). The results illustrated that the plasma/PMS/Fe2O3-CoFe2O4 system possessed high degradation efficiency and TOC removal rate towards three target pollutants (phenol: 99.8%, 96.12%; 4-CP: 98.4%, 86.48%; p-NCB: 99.9%, 88.31%). With the help of in-situ variable temperature EPR and Indigo colorimetry method, · OH, SO4~(·-), O2~(·-), ~1O2 and O3 were identified as the main reactive oxygen species (ROS) for the degradation of target pollutants, revealing the synergistic catalytic mechanism between plasma and Fe2O3-CoFe2O4 for PMS activation and inferring the degradation pathways of target pollutants. The results confirmed that the plasma/PMS/Fe2O3-CoFe2O4 system was feasible for the degradation of refractory organic pollutants, has the advantages of high efficiency and low energy consumption, and could provide an effective strategy for the treatment of refractory organic pollutants in groundwater/soil.
查看更多>>摘要：Recycling valuable elements from municipal solid waste incineration fly ash and air pollution control (APC) residue has become the focus of research to manage this kind of residual waste. This paper assesses the possibility of energy savings to increase the economic sustainability of the electrodialytic (ED) recovery process by using pulsed stirring during extraction of As, Cd, Cr, Cu, Pb, and Zn from fly ash and APC residue suspensions and analyzing the data with multivariate statistical methods. Fly ash and APC residue in different batches were ED treated using different stirring frequencies of the ash suspensions, i.e., manually, 25%, 50%, 75%, and 100% (constant) stirring. An automatic camera was used to record the effect of pulsed stirring on the distribution of the ash suspensions during ED treatment and revealed three stages of the ash suspension during ED treatment that was presented in a conceptual model. The results showed that applying both pulsed and constant stirring could increase the acidification, the redox potential of ash suspensions, and the contact between ash particles and H~+, thus boosting the extraction of metals. The regression coefficients and variable influence on projection values based on partial least squares models show similarity between 50% stirring and 100% stirring, indicating that it is possible to save energy by applying the stirrer only 50% of the time for all ashes, without compromising the extraction of the metals.
查看更多>>摘要：Arsenic (As), an extremely toxic metalloid, has a potential threat to the environment and human health. Crayfish shell, animal-derived biomass, was reused to prepare novel positively charged biochar (CSBC) at 300, 500, and 700 °C (CS300, CS500, and CS700) and the adsorption performance and mechanism of CSBC for As(III/V) were investigated. The results revealed that pyrolysis temperature determined the physicochemical characteristics of CSBC. The maximum adsorption capacities of As(III/V) on the CSBC predicted by the Langmuir model were following as: CS300 (7.71/8.40 mg · g~(-1)) >CS700 (3.61/4.15 mg · g~(-1)) >CS500 (2.61/2.76 mg · g~(-1)), and the adsorption process reached equilibrium after 240 min. The spectroscopic characterization indicated the physical adsorption, electrostatic interaction, and complexation were involved in adsorption mechanisms of As(III/V) by CSBC. Compared with CS500, the variety of functional groups on CS300 facilitated the complexation between it with As and the high degree of aromatization, and more positive charge for CS700 made it had stronger electrostatic interaction with As. These results highlight the significant potential of novel positively charged animal-derived biochar as an adsorbent for As(III/V) removal from aqueous solution.
查看更多>>摘要：In this study, a novel β-cyclodextrin immobilized the three-dimensional macro structure of reduced graphene oxide and multiwall carbon nanotubes (β-CD/rGO-MWCNTs) was synthesized with hydrothermal reduction and chemical crosslinking, adopting as an effective adsorbent for naproxen removal in aquatic environments. With a larger specific surface area (SSA) and excellent porous structure, p-CD/rGO-MWCNTs ensured a large internal space, which was conducive to the preservation of adsorption sites and naproxen diffusion. The maximum naproxen adsorption capacity (qm) value of P-CD/rGO-MWCNTs stood at 132.09 mg g~(-1) at room temperature, higher than that of most of the commonly used naproxen adsorbents. Such immense adsorption was attributed to hydrophobic interaction, electrostatic interaction, π/n-π interaction and hydrogen bonding. The naproxen adsorption kinetics and isotherm on the adsorbents match the pseudo-second-order kinetics model and the Freundlich model better. The thermodynamic parameters certified the naproxen adsorption on β-CD/rGO-MWCNTs as a favorable, thermodynamically feasible and exothermic process. The stable three-dimensional (3D) structure endowed the adsorbent with an excellent regeneration performance and practical application potential.
查看更多>>摘要：The separation and recycling processes of current cyclo dextrin (CD)-based adsorbents are complicated. Thus, a novel composite based on a large surface area, porous, and self-floating tetrafluoroterephthalonitrile (TFN)-crosslinked CD polymer (FTFCD), was fabricated, characterized and applied to treat cationic dye pollutants. The characterization showed a porosity, good thermal stability, a stable crystal structure, and abundant functional groups on the prepared FTFCD, which had demonstrated great improvement on its adsorption capacity towards attention grabbing pollutants. The removal efficiency of the adsorbents for malachite green (MG) remained above 95% at pH 1 ～ 10. In addition, the adsorbents were found to rapidly reach equilibrium governed by the pseudo-second-order kinetic model, and the maximum adsorption capacity of FTFCD was 1390.263 mg/g, as corroborated by the Langmuir isotherm model. While the phenolate groups of FTFCD found to electrostatically interacts with the MG strong cationic quaternary amine group, hydrogen-bonding was responsible for the hydroxyl group of FTFCD and the quaternary amine group binding. Meanwhile, the triangular cone configuration of MG makes it easy to be entrapped and absorbed in the hydrophobic cavity. Besides, after regeneration of exhausted FTFCD for five successive cycles, the MG removal efficiency still reached more than 80%. Thus, FTFCD could be applied as a potential alternative adsorbent for cationic dye removal owing to its excellent adsorption performance, convenient recycling, wide pH application, and environmental friendliness.
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