POLYMER DEGRADATION AND STABILITY
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2018
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IF 3.193
Yong Guan,Rui Yang,Yongkang Huang,Chenchen Yu,Xiang Li,Dafu Wei,Xiang Xu
A small addition amount (0.01–4 phr) of multi-walled carbon nanotubes (MWCNTs) were blended into fluorosilicone rubber (FSR) in order to improve its thermal aging properties, and the paper was investigated from three aspects: (1) the distribution of MWCNTs inside FSR was characterized using scanning electron microscope (SEM); (2) the thermal stability of FSR and FSR/MWCNTs was evaluated by the changes of mechanical performance and weight loss in the thermo-oxidative aging process, and the function mechanism of MWCNTs was studied by thermogravimetric analysis (TGA), chemiluminescence (CL), electron spin resonance (ESR) and fourier transform infrared spectroscopy (FTIR) measurements; (3) the vulcanization properties of FSR and FSR/MWCNTs were obtained from their vulcanization curves employing three kinds of peroxides as vulcanizers. The results showed MWCNTs, with a homogeneous distribution inside FSR, had significantly improved the antioxidant performance of FSR due to their powerful radical scavenging activity. Moreover, MWCNTs revealed no scavenging effect on the tert -butoxy radical, which ensured that FSR/MWCNTs could be well vulcanized.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Liwei Chen,Xu Zuo,Shengjiong Yang,Tianming Cai,Dahu Ding
Rational design and synthesis of efficient catalyst for the generation of sulfate radicals (SO 4 − ) through heterogeneous approach is highly desirable. In the present study, a magnetic cobalt-based catalyst, Co 3 O 4 @Fe 2 O 3 was successfully synthesized by using metal-organic frameworks (MOFs) as a template. A hollow core-shell structure possessing moderate specific surface area (22.8 m 2 g −1 ) and pore volume (0.18 cm 3 g −1 ) was obtained. The catalyst performed high efficiency for the degradation of norfloxacin (NOR) by coupling with peroxymonosulfate (PMS). And the process was kinetically favorable in neutral (0.43 min −1 at pH of 7.5) and weak acidic/basic conditions, whilst significantly inhibited at acidic condition (0.12 min −1 at pH of 4.5). Catalyst loading showed a more remarkable effect on the degradation process than PMS dose. Interestingly, chloride, phosphate and bicarbonate ions clearly promoted the degradation process while humic acid showed a detrimental effect. Cl 2 /HOCl oxidation system was demonstrated when massive Cl − was added into the reaction system. As evidenced by electron paramagnetic resonance (EPR) analysis, both hydroxyl and sulfate radicals contributed to the degradation and the latter one played a crucial role. Eventually, degradation pathway was tentatively proposed based on the HPLC-ESI-MS/MS analysis of the detected intermediates. This study would be very meaningful to promote the applications of sulfate radical based advanced oxidation processes (SR-AOPs) for the environmental remediation.
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高影响因子
JOURNAL OF MATERIALS RESEARCH
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2018
·Vol. 33
·期 21
·3549-3558
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IF 1.495
Mengdie Chen,Haiming Xu,Xiaofang Zhang,Dongya Li,Dongsheng Xia
Activation of persulfate (PS) by ultraviolet light or transition metal catalysts has been extensively studied. However, little is known about the activation of PS by iron oxychloride (FeOCl) in the presence of visible light irradiation. Herein, the catalytic activity of FeOCl was developed for oxidative degradation of rhodamine B (RhB) with the FeOCl/PS/Vis process. The characterization of FeOCl for reaction kinetics, degradation mechanism, and catalyst stability was investigated. It is found that the redox cycle of iron species and photoinduced electrons formed on the FeOCl catalyst surface can effectively activate PS, to generate radicals. Based on quenching experiments and electron paramagnetic resonance, the photogenerated holes (h+) and sulfate radicals (SO4−•) are the predominant reactive oxidants for RhB decolorization, while superoxide radicals (•O2−) and hydroxyl radicals (•OH) are also involved. Moreover, FeOCl shows good catalytic performance in a wide range of pH values (pH = 3–10) and excellent reusability and stability, as well.
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高影响因子
ACS Applied Materials & Interfaces
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2018
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IF 8.097
Lingling Hu,Huanjunwa He,Dehua Xia,Yajing Huang,Jiarong Xu,Haoyue Li,Chun He,Wenjing Yang,Dong Shu,Po Keung Wong
A self-stabilized Z-scheme porous g-C3N4/I3–-containing BiOI ultrathin nanosheets (g-C3N4/I3–-BiOI) heterojunction photocatalyst with I3–/I– redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-C3N4/I3–-BiOI composites were systematically characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, N2 adsorption/desorption, UV–vis diffuse reflectance spectrum, and photoluminescence. The g-C3N4/I3–-BiOI composites, with a heterojunction between porous g-C3N4 and BiOI ultrathin nanosheets, were first applied for the photocatalytic elimination of ppm-leveled CH3SH under light-emitting diode visible light illumination. The g-C3N4/I3–-BiOI heterojunction with 10% g-C3N4 showed a dramatically enhanced photocatalytic activity in the removal of CH3SH compared with pure BiOI and g-C3N4 due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CH3SH over g-C3N4/I3–-BiOI were deeply explored by in situ diffuse reflectance infrared Fourier transform spectroscopy, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, electron spin resonance and Mott–Schottky experiments, it was revealed that the responsible reactive species for catalytic CH3SH composition were h+, •O2–, and 1O2; thus, the g-C3N4/I3–-BiOI heterojunction followed an indirect all-solid state Z-scheme charge-transfer mode with self-stabilized I3–/I– pairs as redox mediator, which could accelerate the separation of photogenerated charge and enhance the redox reaction power of charged carriers simultaneously.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
·
IF 6.735
Shanshan Yang,Pingxiao Wu,Junqin Liu,Meiqing Chen,Zubair Ahmed,Nengwu Zhu
For eliminating organic pollutants from wastewater, Fe 0 or Fe 0 -composites as catalyst for peroxymonosulfate (PMS) activation have attracted increasing attention in advanced oxidation processes. In this work, a novel Fe 0 -montmorillonite composites (Fe-Mt-C-H 2 ) have been prepared by thermal reduction and used as an activator for PMS to remove bisphenol A (BPA). The removal efficiency of BPA (25 mg·L −1 ) and total organic carbon (TOC) were 99.3% and 70.6%, respectively, in the presence of Fe-Mt-C-H 2 (0.4 g·L −1 ) and PMS (1 mM) at pH of 3. Electron paramagnetic resonance (EPR) spectroscopy and radical scavenger studies demonstrated that superoxide radical (O 2 − ) and singlet oxygen ( 1 O 2 ) were the crucial reactive oxygen species (ROS) in the Fe-Mt-C-H 2 /PMS system rather than sulfate (SO 4 − ) and hydroxyl radical (·OH). Besides, it was found that pH had a great influence on the catalytic oxidation rate of BPA and the Fe-Mt-C-H 2 exhibited best catalytic performance and reusability at initial pH of 3. Furthermore, the constituents of the iron surface oxidation layer at different initial pH were investigated with X-ray photoelectron spectroscopy studies, which indicated that the major constituents were Fe 3 O 4 in acidic solution and contained α-Fe 2 O 3 , FeO and FeSO 4 (s) in alkaline or neutral solution. The findings of this study provide new insights into the activation mechanism of PMS by Fe 0 -composites and exhibit a promising application of Fe-Mt-C-H 2 in wastewater treatment.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
·
IF 6.735
Jiali Ge,Xinghao Wang,Chenguang Li,Siyuan Wang,Lianhong Wang,Ruijuan Qu,Zunyao Wang
Polychlorinated diphenyl sulfides (PCDPSs) are a group of dioxin-like compounds that have been widely used in agricultural and industrial productions. Here, we systematically investigated the photochemical behaviors of 2,2′,3′,4,5-pentachlorodiphenyl sulfide (2,2′,3′,4,5-PCDPS) on the surface of silica gel (SG) in an aqueous environment. Under the simulated sunlight irradiation, 2,2′,3′,4,5-PCDPS adsorbed on SG (0.11 mg/g) was found to be degraded with time, giving a removal rate of 68.5% within 16 h at pH 7.0. Environmental factors like pH and humic acid can also affect the removal rate. Results showed that the removal rate of 2,2′,3′,4,5-PCDPS in alkaline conditions (75.6% at pH 11) was higher than that in acidic conditions (46.7% at pH 3). Moreover, the addition of (1–5 mg/L) humic acid can promote the degradation rate compared to control group. In our study, it was found that SG can act as photocatalyst to generate reactive oxygen species (ROS) for the degradation of PCDPSs, and UV light contributed much more than visible light (>420 nm). According to electron paramagnetic resonance (EPR) technology and radicals quenching experiments, hydroxyl radical ( OH), single oxygen ( 1 O 2 ), and superoxide radical ( O 2 − ) participated in the removal of the contaminant. Based on the identified intermediate products via LC–MS, two main pathways, i.e., the hydroxyl-substituted reaction of the benzene ring and the oxidation of the sulfur atom, were proposed for the photodegradation of 2,2′,3′,4,5-PCDPS. Then, the density functional theory (DFT) was employed to confirm these reaction pathways. This study would enhance the understanding of the photochemical transformation and environmental fate of PCDPSs on the surface of solids in natural waters.
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高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Zhenying Jiang,Lingzhi Wang,Juying Lei,Yongdi Liu,Jinlong Zhang
The application of photo-Fenton process is restricted by the acidic pH and additional hydrogen peroxide (H 2 O 2 ). In order to overcome these drawbacks, a photo-Fenton system of CdS/rGO/Fe 2+ which can perform at natural pH with in situ -generated H 2 O 2 has been successfully developed. Highly efficient photo-Fenton degradation of phenol was achieved under the visible light irradiation via the CdS/rGO/Fe 2+ system. Experimental results showed that phenol could be degraded completely in 1 h at natural pH. The plentiful in situ generation of H 2 O 2 was further proved to act as an important role in phenol degradation with the addition of Fe 2+ . The advantages of degradation at natural pH with in situ -generated H 2 O 2 can provide a new prospective to the environmental-friendly Fenton process.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Amina,Xiongyuan Si,Kang Wu,Youbin Si,Balal Yousaf
In this study, a modified Fenton system using calcium peroxide (CaO 2 ) powder, as an effective source of hydrogen peroxide (H 2 O 2 ), for the degradation of sulfamethoxazole (SMX) in aqueous solution was investigated. Our results indicated that degradation of SMX in Fe(II)-EDTA catalyzed CaO 2 system was readily more efficient than in Fe(II) catalyzed CaO 2 system. The SMX degradation efficiency was found maximum at pH 6.0 and SMX degradation was suppressed as the initial solution pH was increased. Nevertheless overall removal efficiency in this system was favorable near to neutral pH. In addition, it was observed that the higher bicarbonates (HCO 3 − ) contents had a considerable scavenging ability to SMX degradation while low concentration exhibited auspicious role. The presence of chlorides (Cl − ), nitrates (NO 3 − ), sulfates (SO 4 2− ), and humic acid (HA) could improve SMX removal in this Fenton-like system. Furthermore, chemical probe and radical scavenging activity confirmed the formation of hydroxyl (HO ) and superoxide (O 2 − ) radicals, and also described that the SMX degradation was predominantly due to the HO -induced oxidative destruction. Electron paramagnetic resonance (EPR) studies for different systems, different pH values and different reaction times were carried out to determine the HO radical intensities. EPR results showed that HO intensities were higher in Fe(II)-EDTA catalyzed CaO 2 system, at pH 6.0 and at 90 s reaction time, respectively. Intermediate products of SMX were identified and possible mechanism of SMX degradation was suggested. In conclusion, this work provided comprehensive knowledge for the use of Fe(II)-EDTA catalyzed CaO 2 system for remediation of SMX contaminated sites.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2018
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IF 3.927
Ying Liu,Deli Wu,Shuhan Peng,Yong Feng,Zhigang Liu
Cu-Fe-O nanoparticles (CFO NPs), synthesized with zero-valent iron (ZVI) and Cu(NO 3 ) 2 as the metal precursors, were used to enhance ozonation to degrade dimethyl phthalate (DMP). Great DMP degradation and mineralization rates were achieved in a wide range of the initial pH values (3–9); the amount of OH in catalytic ozonation was much higher than that of O 3 alone at the initial pH of 5.70. The generation of hydroxyl radicals ( OH), methyl radicals ( CH 3 ) and superoxide radicals (O 2 − ) were identified and OH mainly contributed to DMP removal. The potential of Fe(III)/ Fe(II) and Cu(II)/ Cu(I) cycles have largely been overlooked, which was found to be the key for producing more OH in CFO/O 3 system. The underlying mechanisms were probably initiated by a chain reaction: initiated O 3 reaction with Cu(I)/ Fe(II) OH to form OH and O 2 − , accelerated reaction between Cu(II)/ Fe(III) and the in situ generated O 2 − with a relatively high reaction constant, redox reaction between Cu(I) and Fe(III), OH oxidizing reaction with DMP to produce CH 3 . In addition, different degradation pathways of DMP were proposed based on the intermediates in the presence of CH 3 . This study sheds new light on the specific radical chain reaction mechanisms of catalytic ozonation.
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高影响因子
Journal of Materials Chemistry B
·
2018
·Vol. 7
·期 2
·296-304
·
IF 4.776
Yan-Wen Bao,Xian-Wu Hua,Huan-Huan Ran,Jia Zeng,Fu-Gen Wu
Nanomaterial-based enzyme mimics (nanozymes) are attracting increasing attention because of their low production cost, high stability against denaturation, and resistance to high concentrations of substrates. Here, carbon nanoparticles doped with a small amount (<5 mol%) of Pt (denoted as PtCNPs) are synthesized via a facile, cost-effective hydrothermal treatment of p-phenylenediamine (PPD) and K2PtCl4. The obtained PtCNPs possess high aqueous stability, excellent water-dispersibility, and suitable size (∼15 nm). More interestingly, the PtCNPs exhibit an intrinsic peroxidase-like activity that can quickly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) and produce a blue color. Importantly, since satisfactory catalytic properties were also observed when K2PtCl4 was replaced with CuCl2, NiCl2, or Na2PdCl4 during the synthesis, the PPD- and inorganic metal salt-involved hydrothermal synthetic approach may be developed as a general and simple way to fabricate new nanozymes. Besides, the steady-state kinetics reveals that the PtCNPs have a stronger affinity for TMB and a weaker affinity for H2O2 compared with horseradish peroxidase. On the basis of the color reaction, a colorimetric detection method for H2O2 and glucose has been successfully established with a detection limit of 0.15 and 0.30 μM, respectively. Further, the method has also been successfully applied for glucose detection in human serum samples. To sum up, this work develops a new synthetic method of metal-doped carbon nanomaterials and demonstrates their capability for the sensitive and selective detection of H2O2 and glucose, which may foster the development of new nanozymes for biosensing applications.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Peng Zhou,Jing Zhang,Gucheng Zhang,Wenshu Li,Yang Liu,Xin Cheng,Xiaowei Huo,Yunxin Liu,Yongli Zhang
The oxidation capacity and mechanisms involved in activation of peroxomonosulfate (PMS) by nanoscale zero valent tungsten (nZVW) were investigated with dimethyl phthalate (DMP) as a targeted contaminant. DMP removal was completely achieved by hydroxyl radical ( OH) and sulfate radical ( SO 4 − ) at 50 min in the nZVW/PMS system, and structural and componential changes of nZVW powder before and after reaction were not obvious. Low valence tungsten species were released during nZVW corrosion in oxygenated water via heterogeneous reactions, which was accelerated by PMS. The homogeneous reactions were mainly responsible for radical generation: 1) the stepwise oxidation of nZVW to produce H 2 O 2 , which was then activated by low valence tungsten species to generate OH; 2) the activation of PMS by low valence tungsten species to produce SO 4 − and OH. However, OH − reduced the reactivity of low valence tungsten species due to the formation of tungstate, higher pH thus partly inhibited the DMP removal. Two stages of DMP removal were found, and DMP degraded dramatically in the second stage. The degradation pathways of DMP were proposed, involving the formation of aromatic esters (monomethyl phthalate, methyl benzoate, and methyl salicylate), aromatic acids (phthalic acid, salicylic acid, and benzoic acid), and phenols (catechol, phenol, and hydroquinone) in turn. These results help to comprehend the application of nZVW in reactive radicals-based oxidation processes and the reactivity of low valence tungsten species in water treatment field.
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高影响因子
CHEMOSPHERE
·
2018
·
IF 4.427
Xueming Lin,Yongwen Ma,Jinquan Wan,Yan Wang,Yongtao Li
In this study, FeMoO 4 was applied to activate persulfate (PS, S 2 O 8 2− ) for azo dye Orange G (OG) degradation. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption isotherms. FeMoO 4 showed excellent efficiency in activating PS for OG removal. More than 95% could be removed after 40 min under reaction conditions of 4 mM PS, 0.3 g L −1 FeMoO 4 and 0.2 mM OG. The effect of different parameters (PS doses, FeMoO 4 doses and pH) were evaluated. The results showed that acid condition provided higher efficiency and overdosing FeMoO 4 and PS presented a scavenging effect. Major intermediates were identified and possible degradation pathway was proposed. Recycle tests presented that FeMoO 4 had excellent recyclable stability in activating PS for OG removal. Sulfate radicals and hydroxyl radicals all occurred in the oxidation reactions and the former came first. The oxidation reaction was involved in the translation of Fe 2+ /Fe 3+ occurred on the surface layer. This study revealed that the FeMoO 4 /PS system is a very promising method for degrading organic contaminants in the environment.
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高影响因子
危险品化学品经营许可证（带存储）