Peifang Wang

Hohai University, Nan-ching, Jiangsu Sheng, China

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Publications (56)94.57 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The unsaturated fatty acid (linoleic acid) sustained-release microspheres were prepared with linoleic acid (LA) using alginate–chitosan microcapsule technology. These LA sustained-release microspheres had a high encapsulation efficiency (up to 62%) tested by high performance liquid chromatography with a photo diode array. The dry microspheres were characterized by a scanning electron microscope, X-ray diffraction measurement, dynamic thermogravimetric analysis and Fourier transform infrared spectral analysis. The results of characterization showed that the microspheres had good thermal stability (decomposition temperature of 236 °C), stable and temperature independent release properties (release time of more than 40 d). Compared to direct dosing of LA, LA sustained-released microspheres could inhibit Microcystis aeruginosa growth to the non-growth state. The results of this study suggested that the LA sustained-release microspheres may be a potential candidate for algal inhibition.
    Chemosphere 01/2015; 120:383–390. · 3.14 Impact Factor
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    ABSTRACT: This study investigated the kinetics of phenol and 4-chlorophenol (4-CP) biodegradation by a cold-adapted bacteria, Pseudomonas putida LY1, isolated from Songhua River sediment. The results showed that P. putida LY1 cannot grow on 4-CP as a sole carbon source. P. putida LY1 had the potential to cometabolic biodegrade phenol and 4-CP in a wide range of temperature (varying from 5 to 35 °C) with the optimal temperature around 25 °C. Mixture of phenol and 4-CP were completely removed at two 4-CP concentrations (15 and 40 mg/L) over a wide range of phenol (20-400 mg/L) concentrations, whereby the ratio of 4-CP/biomass (S 2/X) was lower than 0.03. The kinetic models of cometabolic biodegradation of phenol and 4-CP were proposed, considering the growth and nongrowth substrate inhibition. These models successfully simulate the processes of cometabolic degradation of phenol and 4-CP.
    Environmental science and pollution research international. 08/2014;
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    ABSTRACT: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O2 respiration activities of aerobic wastewater biofilms were investigated using an O2 microelectrode. The resulting time-course microelectrode measurements demonstrated that ZnO NPs inhibited O2 respiration within 2h. The spatial distributions of net specific O2 respiration were determined in biofilms with and without treatment of 5 or 50mg/L ZnO NPs. The results showed that 50mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O2 respiration induced by higher concentrations of ZnO NPs (50mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs.
    Journal of hazardous materials. 04/2014; 276C:164-170.
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    ABSTRACT: Purpose Sediments are significant methane (CH4) sources of the atmosphere. However, the mechanisms of CH4 generation remain unclear in sediments of shallow urban lakes. The aims of this investigation were to study the characterization of environmental parameters, CH4 generation, and methanogen populations in Wulongtan Lake, China, which is affected solely by nonpoint pollution. Materials and methods The concentrations of CH4 in the atmosphere and of vertical sediment profiles and the methane flux at the air–water interface were monitored in the summer of 2012. Environmental parameters in the water column and in the vertical sediment profiles were assayed. The activities of cellulose, saccharase, polyphenol oxidase, and urease enzyme and 16S rRNA gene copy numbers of Archaea (ARC), Methanobacteriales (MBT), Methanococcales (MCC), Methanomicrobiales (MMB), Methanosarcinales (MSL), Methanosarcinaceae (MSC), and Methanosaetaceae (MST) were determined in the vertical sediment profiles. The abundance of methyl–coenzyme A reductase (ME) gene was also determined to evaluate the total activities of methanogens. Results and discussion High CH4 concentrations were detected in the atmosphere above the lake, and the mean CH4 flux at the air–water interface was 6.21 mM m−2 h−1. Dissolved oxygen decreased with an increase of water depth. Eh values and CH4 contents increased, but total nitrogen, water content, and total organic carbon (TOC) decreased with an increase of sediment depth. Cellulose, saccharase, polyphenol oxidase, and urease activities were detected in all sedimentary layers. The copy number of 16S rRNA gene (wet weight) for Archaea reached the highest value in the surface sediment. Copy numbers of ME were higher at 12–33 cm than at 0–6 cm. In general, abundances of MMB, MBT, and MSL were higher than that of MCC in the same sedimentary layer. 16S rRNA gene copy numbers of MST decreased with increasing depth, while MSC was higher at 18–27 cm than that at other sections. These indicate that hydrogenotrophic, aceticlastic, and methylotrophic pathways coexisted in these sediments. Principal component analysis revealed that in the sediments, the level of CH4 was closely related with several parameters including saccharase, urease, ME, and MBT, while TOC content was related to CEL, MST, ARC, water content, and Eh. Conclusions High CH4 release potential was detected in this shallow urban lake and can be ascribed to the anaerobic aquatic environment, bacterial enzyme activities, and methanogens. The orders MMB, MBT, and MSL were dominant in sediments for CH4 production. The presence of orders or families of methanogens might be determined by the types of available substrates in lake sediments.
    Journal of Soils and Sediments 02/2014; · 1.97 Impact Factor
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    ABSTRACT: Flume experiments were conducted to investigate the distribution and composition of extracellular polymeric substances (EPS) in biofilms and the detachment mechanism of biofilms grown under different flow velocity conditions. The results of biofilm growth kinetics showed that the growth trends were coincident with the logistic growth model. The growth kinetics parameters reached their maximum under intermediate velocity (IV) condition. Biofilms exhibited different profiles of EPS composition and distribution, depending on the flow conditions in which the biofilms were grown. The amounts of total polysaccharide and total protein in the thin biofilm (high velocity condition 2 - HV2) were both generally greater than those in the thick biofilm (IV). As compared to the heterogeneous distribution of EPS in the thick biofilms (IV), the EPS in the thin biofilms (HV2) exhibited more homogeneous distribution, and the bound EPS in the thin biofilms (HV2) were much greater than those in the thick biofilms (IV). From the detachment tests, an inverse relationship was observed between the proportion of detached biomass and the value of flow velocity during growth. Biofilms grown under higher velocities showed stronger cohesion than those grown under lower velocities. Therefore, water velocity during biofilm growth conditioned the distribution and composition of EPS, as well as its detachment characteristics under higher shear stress.
    Water Science & Technology 02/2014; 69(4):825-832. · 1.10 Impact Factor
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    ABSTRACT: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O2 respiration activities of aerobic wastewater biofilms were investigated using an O2 microelectrode. The resulting time–course microelectrode measurements demonstrated that ZnO NPs inhibited O2 respiration within 2 h. The spatial distributions of net specific O2 respiration were determined in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O2 respiration induced by higher concentrations of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs.
    Journal of Hazardous Materials. 01/2014; 276:164–170.
  • Yanhui Ao, Hong Tang, Peifang Wang, Chao Wang
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    ABSTRACT: Ag@AgCl–BiOCl nanocomposites were prepared by an in-situ ultraviolet (UV) reduction method. BiOCl in the composites exhibits morphology of square-like 2D nanoplates. The results indicated that there was an optimum irradiation time (30 min) for obtaining the highest photocatalytic activity.
    Materials Letters. 01/2014; 131:74–77.
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    ABSTRACT: Graphene–carbon nanotubes (CNTs)–TiO2 composites were successfully synthesized by a one-pot solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and diffuse reflectance UV–vis spectra. The photocatalytic activity of as-prepared composite photocatalysts was tested by degradation of dye methylene blue (MB) and photoreduction of Cr(VI) in aqueous solution under UV light irradiation. The experiment results showed that the composites exhibited enhanced photocatalytic performance compared to binary one (i.e. graphene–TiO2) and pristine TiO2. The effect of CNTs content on the photocatalytic activity was also studied. It showed that the photocatalytic performance of the graphene–CNTs–TiO2 hybrids was dependent on the proportion of CNTs in the composite. The mass ratio of CNTs:TiO2 = 5% was proved to be the optimal ratio. The apparent rate constants k for MB degradation and Cr(VI) reduction were 2.2 and 1.9 times as graphene–TiO2 composite, respectively. The enhanced activity can be ascribed to the addition of CNTs, which can be severed as charge transmitting paths thus decrease the recombination rate of photoinduced electron–hole pairs. This mechanism for the enhanced photoactivity was further confirmed by measuring the hydroxyl radical and transient photocurrent.
    Applied Catalysis A: General. 01/2014; 473:83–89.
  • Qing Wang, Yi Li, Chao Wang, Yue Wu, Peifang Wang
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    ABSTRACT: A novel bio-reactive capping barrier composed of polysulfone/granular activated carbon (PS/GAC) hybrid membranes immobilized with microorganism was developed for the remediation of nitrobenzene in sediments. The SEM observation demonstrated that all the membranes had a dense top layer and a porous sublayer, this structure can block the transfer of nitrobenzene from sediment to the water and enhance nitrobenzene degradation. Adsorption behaviors of nitrobenzene on membranes showed that the membrane impregnated with GAC had better performance than the pure PS membrane. The values of Kads increased from 4.64 (without GAC) to 6.19 (1:2 GAC). 20mg/L nitrobenzene can be completely degraded by Pseudomonas putida immobilized on membranes. The biodegradation rate of activated carbon-filled membrane system was little higher than that of pure PS membrane system. For remediation experiments, only about 21.7, 28.3 and 43.9% of nitrobenzene in the sediment was removed by the end of the experiments for PS/GAC membrane, sand-alone and sand amended with activated carbon capping systems, respectively. While for PS/GAC+microorganisms capping system, more than 70% of nitrobenzene loss was observed. This demonstrated that nitrobenzene can be effectively removed from contaminated sediments by microbial degradation in the bio-reactive capping system.
    Journal of Hazardous Materials. 01/2014; 276:415–421.
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    ABSTRACT: A solvothermal method was employed to prepare a novel magnetic composite adsorbent composed of graphene, multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles. The prepared adsorbents were characterized by X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectrometry and Fourier transform infrared spectroscopy. Fourier transform infrared spectroscopy and the particle size distribution of the samples before and after adsorption was also carried out. The performance of as-prepared composites was investigated by the adsorption of dye methylene blue. Results showed that the maximum adsorption capacity of the samples was up to 65.79 mg g−1, which was almost equal to the sum of magnetic graphene and magnetic MWCNTs. The effect of pH and temperature on the adsorption performance of methylene blue onto the magnetic adsorbents was investigated. The kinetic was well-described by pseudo-second-order and intraparticle diffusion model, while the isotherm obeyed the Langmuir isotherm. Furthermore, the as-prepared composites were found to be regenerative and reusable. The application in the treatment of an artificial dye wastewater and its cost estimation were also discussed. Therefore, the as-prepared magnetic composites can be severed as a potential adsorbent for removal of dye pollutant, owing to its high adsorption performance, magnetic separability and efficient recyclable property.
    Applied Surface Science 01/2014; 290:116–124. · 2.54 Impact Factor
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    ABSTRACT: A series of mesoporous BiOBr–activated carbon (AC) composite photocatalysts with different content of AC were synthesized by an in situ loading solvothermal method. The obtained samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area and UV/vis diffuse reflectance spectrum (DRS). Results showed that the composite samples exhibit higher BET values and stronger adsorption ability for organic pollutants. Moreover, the existence of AC influenced the size of BiOBr deposited on ACs. High photocatalytic activity was observed for the degradation of the heteropolyaromatic dye methylene blue (MB) under both UV and visible light irradiation. Additionally, the results indicated that there was an optimum AC amount of 80% for obtaining the highest photocatalytic activity.
    Composites Part B Engineering 01/2014; 59:96–100. · 2.14 Impact Factor
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    ABSTRACT: Ag nanoparticles loaded TiO2 nanoplate array which grew on activated carbon fiber (ACF) was prepared for the first time. Results showed that the Ag nanoparticles deposited uniformly on the titania nanoplate array, which grew nearly perpendicularly on the activated carbon fiber. The obtained samples showed high photocatalytic activity for phenol degradation under both UV and visible light.
    Catalysis Communications 01/2014; 53:21–24. · 2.92 Impact Factor
  • Lei Rao, Junling Xu, Yanhui Ao, Peifang Wang
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    ABSTRACT: Graphene/ZnWO4 (G–ZnWO4) nanorod composite photocatalysts were prepared by a simple one-step method. Namely, the reduction of graphene oxide and the growth of ZnWO4 nanorod occurred simultaneously in one single process. An enhancement in the photocatalytic activities were observed in G–ZnWO4 composites compared with pure ZnWO4 under UV light irradiation.
    Materials Research Bulletin. 01/2014; 57:41–46.
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    ABSTRACT: Sustainable design and implementation of wastewater reuse in China have to achieve an optimum compromise among water resources augmenting, pollutants reduction and economic profit. A systematic framework with a multi-objective optimization model is firstly developed considering the trade-offs among wastewater reuse supplies and demands, costs and profits, as well as pollutants reduction. Pareto fronts of wastewater reuse optimization for 31 provinces of China are obtained through non-dominated sorting genetic algorithm trials. The control strategies for each province are selected on the basis of regional water resources and water environment status. On the national level, the control strategies of wastewater reuse scale, BOD5 reduction, and economic profit are 15.39 billion cubic meters, 176.31 kilotons, and 9.68 billion RMB Yuan, respectively. The driving forces of water resources augmenting and water pollution control play more important roles than economic profit during wastewater reuse expanding in China. According to the optimal allocations, reclaimed wastewater should be intensively used in municipal, domestic, and recreative sectors in the regions suffering from quantity-related water scarcity, while it should be focused on industrial users in the regions suffering from quality-related water scarcity. The results present a general picture of wastewater reuse for policy makers in China.
    Environmental Science & Technology 12/2013; · 5.26 Impact Factor
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    ABSTRACT: The Yangtze Estuary is heavily influenced by coast-continent geochemical processes and anthropogenic activity; thus, the source and distribution of chromophoric dissolved organic matter (CDOM) in the estuary are strongly impacted by these processes. Here, a series of samples were collected from across the Yangtze Estuary to investigate the source and spatial dynamics of CDOM and its components throughout the system. Three indices (a(355), spectral slope, and fluorescence) were then calculated and interpreted. The results indicated that the distribution of CDOM was dominated by allochthonous input, conservative mixing, and phase transfer. The contribution of biogenic CDOM to total CDOM increased with salinity, and three individual CDOM components were identified upon fluorescence excitation emission matrix spectroscopy and parallel factor analysis of the water samples: C1, corresponding to humic substance-like CDOM, C2, corresponding to tryptophan-like CDOM, and C3, corresponding to tyrosine-like CDOM. C1 primarily originated from a terrestrial source, C2 had widespread origins, none of which played a dominant role, and C3 mainly originated from allochthonous input in the medium salinity area. Unexpectedly, no marine humic-like component was found in the surface water of the Yangtze Estuary, possibly because turbidity decreased the depth of sunlight penetration, limiting production of this component.
    Environmental Science and Pollution Research 11/2013; · 2.76 Impact Factor
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    ABSTRACT: Ag/AgCl@chiral TiO2 nanofibers are synthesized to tune the angle of the incident visible light through the chiral structure of the TiO2 nanofibers, intensifying the surface plasmon resonance effect of the supported Ag/AgCl materials, which are proven to be a highly active and stable visible light photocatalyst for the degradation of 17-β-ethinylestradiol.
    Chemical Communications 09/2013; · 6.38 Impact Factor
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    ABSTRACT: The spread of antibiotic-resistance bacteria and antibiotic-resistance genes (ARGs) has been of concern worldwide. In this study, 114 Escherichia coli isolates were isolated from surface water samples of a lake to identify their susceptibility to antibiotics, including tetracycline (TC), gentamicin (GN), ampicillin (AMP), streptomycin (ST), oxytetracycline (OC), levofloxacin (LEV), nalidixic acid (NA), and sulfamethoxazole/trimethoprim (SFT). Isolates showing resistance to TC, GN, AMP, ST, OC, LEV, NA, and SFT occurred in 50, 76, 68, 71, 55, 32, 82, and 85 % of the total isolates, respectively. Thirty-seven different resistance patterns were identified, and the most abundant resistance profile (28 of 104) was TC/GN/AMP/ST/OC/LEV/NA/SFT. The occurrence of 29 ARGs were detected in their corresponding resistance clones, and 88 % of TC-resistance, 94 % of SFT-resistance, 90 % of AMP-resistance, 78 % of ST-resistance, and 72 % of quinolone-resistance clones can be described by their corresponding ARGs. It should be noted that most of these antibiotic-resistance clones harbored at least two corresponding ARGs, indicating that high frequencies of combined ARGs occurred in these isolates. In addition, 9 new types of DNA sequence of qnr(B) gene were obtained and were clustered into the same group as showed by phylogenetic trees analysis. These results suggest that the development of antibiotic resistance can be ascribed to the high frequency in the recombination of ARGs through horizontal gene transfer.
    Archives of Environmental Contamination and Toxicology 07/2013; · 2.01 Impact Factor
  • Yanhui Ao, Peifang Wang, Chao Wang, Jun Hou, Jin Qian
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    ABSTRACT: Graphene oxide/Ag3PO4 (GO–Ag3PO4) composite photocatalysts were prepared by a simple precipitant method. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity was investigated by the degradation of MB. An increase in photocatalytic activity was observed for GO–Ag3PO4 composite materials compared with pure Ag3PO4 under visible light. This improvement was attributed to the following two reasons: increased migration efficiency of photo-induced electrons and increased adsorption activity for dye molecules. A study of the effect of the amount of GO on the photocatalytic activity showed that there was an optimum amount of 10%.
    Applied Surface Science 04/2013; 271:265–270. · 2.54 Impact Factor
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    ABSTRACT: The mechanisms of simultaneous photocatalytic hydrogen production and estrogenic activity (EA) removal from secondary effluent were investigated by evaluating the effects of initial dissolved oxygen (DO), organic matter, and inorganic ions on the process. The photocatalytic process was enhanced and can be divided into two phases according to the availability of DO. In aerobic phase, the humic/fulvic-like compounds in hydrophilic substances fraction were preferentially decomposed by aerobic photo-formed reactive oxygen species (i.e. O2(-), h(+), and OH) with generation of electron donors (i.e. formaldehyde, acetaldehyde, acetate, and formate). Approximately 41% of dissolved organic carbon and 90% of EA were reduced in the aerobic phase. In the following anoxic phase, the hydrogen production was significantly improved (apparent photonic efficiency 3.04 × 10(-3)) by the generated electron donors and accompanied with completely EA removal by the anoxic photo-formed OH. Hydrogen production was enhanced with the presence of low concentrations of [Formula: see text] (below 0.1 mmol/L) and [Formula: see text] (below 0.2 mmol/L) through accelerating electrons accumulation while it was inhibited at high concentrations since the formed ion-radicals could not decompose humic/fulvic-like compounds. EA removal was inhibited by [Formula: see text] and [Formula: see text] through scavenging h(+)/$OH. The presence of [Formula: see text] (below 1 mmol/L) only resulted in minor impacts since [Formula: see text] was almost unreactive toward electronor OH in neutral conditions.
    Water Research 03/2013; · 4.66 Impact Factor
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    ABSTRACT: In the present paper, the TiO nanorod arrays electrode was developed as a sensor for the determination of chemical oxygen demand (COD) based on a photoelectrochemical degradation principle. Effects of common parameters, such as applied potential, light intensity and pH on its analytical performance were investigated. Under the optimized conditions, the nanorod arrays electrode was successfully applied in the COD determination for both synthetic and real samples. In the COD determination, the proposed method can achieve a practical detection limit of 18.3mgL and a linear range of 20-280mgL. Furthermore, the results obtained by the proposed method were well correlated with those obtained using the conventional (i.e., dichromate) COD determination method. The main advantages of this COD determination method were its simplicity, long term stability and environmental friendly (corrosive and toxic reagents not consumed). This work would open a new application area (COD determination) of the TiO nanorod arrays.
    Analytica chimica acta 03/2013; 767:141-7. · 4.31 Impact Factor