Daily Variation of Natural Emission of Methane to the Atmosphere and Source Identification in the Luntai Fault Region of the Yakela Condensed Oil/Gas Field in the Tarim Basin,Xinjiang,China

The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry （GC/C/MS）, 13^C/12^C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m^2·d, the lowest 4.38 mg/m^2, and the average 7.55 mg/ m^2·d. The 13^C/12^C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.

农用纳米二氧化硅载体对作物生长影响的研究

近年来,纳米二氧化硅在农业中的应用越来越广泛,评价纳米二氧化硅对农作物生长的影响日益迫切。该文采用了经典的幼苗根伸长试验,研究了纳米二氧化硅(平均尺度14.0 nm,NP-Si)对卷心菜、胡萝卜和黄瓜3种蔬菜生长的影响;同时研究了亚微米二氧化硅(MP-Si,平均尺度为667.6 nm)对蔬菜生长的影响以作对比。结果显示,NP-Si对这3种蔬菜幼苗的生长均具有促进作用,且在脱离了NP-Si的接触后,此促进作用在实验周期内没有逆转;而MP-Si对蔬菜幼苗的生长无影响。多环芳烃菲的吸附将NP-Si对这3种蔬菜幼苗的促生长作用改变为抑制作用。FTIR的测定表明,多环芳烃菲的吸附前后,NP-Si的红外光谱有所不同。研究结果表明:(1)NP-Si对农作物生长的影响不仅仅来源于其纳米的尺度,还与其表面吸附的物质有关;(2)纳米材料表面的吸附作用及吸附的物质是在纳米材料对农作物生长影响的研究中必须考虑的重要因素。

Evidence against hydroxyl radical mechanism in photo-Fenton degradation of p-chlorophenol

This paper provides evidence for the degradation of organic pollutant by the photo-Fenton complex mechanism. Both the complex oxidation and HO. oxidation mechanisms were verified by p-chlorophenol degradation, UV/Vis spectra anaylsis, and quantum yield. The hydroxyl radical involved in the photo-Fenton process can also be generated from the decomposition of H2O2, photolysis of Fe^3＋ and degradation of hydrated Fe（Ⅵ）-complex, excepting the traditional Fenton reaction.

Removal of nickel from spent electroless nickel-plating bath with nickel foam cathode

The electrochemical method was used to remove nickel ion from spent electroless nickel plating bath (pH=5 3). An electrolytic cell was composed of a porous nickel foam cathode and an inert RuO 2/Ti anode. Nickel ions were reduced and deposited on the surface of the nickel foam cathode. The effect of current density (i), linear velocity of wastewater(v), gap between cathode and anode(d C/A) and reaction time(t) on nickel removal rate and current efficiency were studied. As reaction time prolonged, nickel removal rate increased while current efficiency decreased. And larger v and smaller d C/A can enhance nickel removal rate and increase current efficiency by promoting mass transfer and dropping concentration polarization. The effect of current density on nickel removal by electrochemistry was related to other parameters. After three hours’ electrolysis with i=1 0 A/dm2, v=18 5 cm/min and d C/A=0 5 cm, nickel removal rate and current efficiency reached 85 6% and 29 1%, respectively.

Effect of sulfate on the methanogenic activity of a bacterial culture from a brewery wastewater during glucose degradation

The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.

Greywater Treatment by High Rate Algal Pond under Sahelian Conditions for Reuse in Irrigation

High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored. With a hydraulic retention time of 7.5 days and a solid retention time of 20 days, the average removal efficiencies (ARE) were 69% and 62% for BOD5 and COD respectively. The ARE for , and were 23%, 52% and 43% respectively. The removal of suspended solids (SS) was unsatisfactory, which could be attributed to the low average algal settling efficiencies of 9.3% and 16.0% achieved after 30 and 60 minutes respectively. The ARE of fecal coliforms, Escherichia coli and enterococci were 2.65, 3.14 and 3.17 log units respectively. In view of the results, the HRAP technology could be adapted for greywater treatment in sahelian regions. However, further studies on the diversity of the algal species growing in the HRAP unit are necessary in order to increase the removal of SS. Hazards of a reuse of the effluents are discussed on the basis of the various qualitative parameters. The residual content of E. coli was varying from 4 CFU per 100 mL. Based on WHO guidelines for greywater reuse in irrigation, the effluents could be used for restricted irrigation (E. coli < 105 CFU per 100 mL). Furthermore, the reuse potential is discussed on the basis of FAO guidelines using SAR (3.03 to 4.11), electrical conductivity (482 to 4500 μS/cm) and pH values (6.45 to 8.6).

Hydrogen Smart-Grids: Smart Metering of Electricity from Hydrogen Fuel Cells

In the last decade, increasing applications of information technology (IT) within power industry has become a significant reality. As distributed power networks are gaining importance and renewables are getting a bigger ratio within energy production, Smart Grid applications have become essential, especially due to the intermittent nature of renewable energy resources. Smart Grid is a sustainable energy system that measures, checks, and controls the generation, transmission, and consumption of electrical energy in grids on all voltage levels. Smart Grid experts are driving forward the development of effective communication and information technologies for the build-up of intelligent power supply networks. Examples of these are control systems for the realization of virtual power plants, intelligent consumer data acquisition systems, and smart distribution management systems. Fuel cell-based hydrogen electricity, in comparison to other renewable energy sources, is more stable and predictable. Yet hydrogen power and smart-grids have many application points, mainly as means of energy storage. This study claims that hydrogen energy and smart-grids could also engage through an appliance of IT managed metering of hydrogen power production. Smart metering and management of hydrogen fuel cells would enable advanced planning of short-to-mid-term power productions and thus foster use of hydrogen power within distributed networks, as local community or industrial applications.

Elimination of antibiotic resistance genes and control of horizontal transfer risk by UV-based treatment of drinking water: A mini review

Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been recognized as one of the biggest public health issues of the 21 st century. Both ARB and ARGs have been determined in water after treatment with conventional disinfectants. Ultraviolet (UV) technology has been seen growth in application to disinfect the water. However, UV method alone is not adequate to degrade ARGs in water. Researchers are investigating the combination of UV with other oxidants (chlorine, hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and photocatalysts) to harness the high reactivity of produced reactive species (C1-, C1O -, Cl2-,-OH, and SO4-_) in such processes with constituents of cell (e.g., deoxyribonucleic acid (DNA) and its components) in order to increase the degradation efficiency of ARGs. This paper briefly reviews the current status of different UV-based treatments (UV/chlorination, UV/H2O2, UV/PMS, and UV-photocatalysis) to degrade ARGs and to control horizontal gene transfer (HGT) in water. The review also provides discussion on the mechanism of degradation of ARGs and application of q-PCR and gel electrophoresis to obtain insights of the fate of ARGs during UV-based treatment processes.

Coupling of zero valent iron and biobarriers for remediation of trichloroethylene in groundwater

This study attempted to construct a three series barrier system to treat high concentrations of trichloroethylene （TCE; 500 mg/L） in synthetic groundwater. The system consisted of three reactive barriers using iron fillings as an iron-based barrier in the first column, sugarcane bagasse mixed with anaerobic sludge as an anaerobic barrier in the second column, and a biofilm coated on oxygen carbon inducer releasing material as an aerobic barrier in the third column. In order to evaluate the extent of removal of TCE and its metabolites in the aquifer down gradient of the barrier system, a fourth column filled with sand was applied. Residence time of the system was investigated by a bromide tracer test. The results showed that residence time in the column system of the control set and experimental set were 23.62 and 29.99 days, respectively. The efficiency of the three series barrier system in removing TCE was approximately 84% in which the removal efficiency of TCE by the iron filling barrier, anaerobic barrier and aerobic barrier were 42%, 16% and 25%, respectively. cis-Dichloroethylene （cis-DCE）, vinyl chloride （VC）, ethylene and chloride ions were observed as metabolites following TCE degradation. The presence of chloride ions in the effluent from the column system indicated the degradation of TCE. However, cis-DCE and VC were not fully degraded by the proposed barrier system which suggested that another remediation technology after the barrier treatment such as air sparging and adsorption by activated carbon should be conducted.

Assessment of solar-assisted electrooxidation of bisphenol AF and bisphenol A on boron-doped diamond electrodes

Bisphenol(BP)analogues in wastewater effluent and groundwater pose a potential threat to human health due to their ability to disrupt steroidogenesis.A new solar-assisted electrochemical process(SECP)was developed and evaluated for the degradation of BP analogues.The effects of quenchers,current density,initial pH,supporting electrolyte,and aqueous matrix on the removal kinetics of bisphenol AF(BPAF)and bisphenol A(BPA)were investigated.The kinetic constants of BPAF,BPA,and bisphenol S(BPS)in the SECP with irradiation intensity of 500 mW cm^(-2) were 0.017±0.002 min^(-1),0.022±0.002 min^(-1),and 0.012±0.001 min^(-1),respectively.The changes in the degradation rates of BPAF,BPA,and BPS in the presence of quenchers indicated the relative contribution of hydroxyl radical(·OH)oxidation,anodic electrolysis,and singlet(^(1)O_(2))oxygenation in the degradation of BPs in the SECP.The enhanced rate of generation of ·OH and ^(1)O_(2) was observed in the SECP compared with those in the conventional electrochemical system.The identification of the transformation products(TPs)of BPAF demonstrated that hydroxylation,ring cleavage,b-scission,and defluorination were the major processes during the oxidation in the SECP.The conversion to fluoride ions(76%)and mineralization of total organic carbon(72%)in the SECP indicated further degradation of TPs.The results from this study improved our understanding of the degradation of BP analogues in the electrooxidation irradiated by solar light and help to establish the application potential of the SECP for the effective degradation of emerging contaminants in wastewater.

Two-dimensional RGO-bridge S-scheme phosphorus-doped g-C_(3)N_(4)/Bi_(5)O_(7)Ivan der Waals heterojunctions for efficient visible-light photocatalytic treatment of real pharmaceutical wastewater

The design of van der Waals heterojunctions with S-scheme charge transfer pathway is expected to be an effective strategy for improvement of photocatalytic performance.Herein,two-dimensional(2D)phosphorus-doped g-C_(3)N_(4)/Bi_(5)O_(7)Ivan der Waals heterojunctions with reduced graphene oxide as electron bridge(PCN/RGO/Bi_(5O)_(7)I)were successfully synthesized via hydrothermal method.The van der Waals interaction endowed 2D PCN/RGO/Bi_(5O)_(7)I with intimate contact interface,lattice match,tunable band structure,and internal electric field,which efficiently promoted interfacial charge separation and enhanced redox ability of photogenerated charge carriers.As a result,the S-scheme PCN/RGO/Bi_5O_7I van der Waals heterojunctions exhibited superior photocatalytic performance in ciprofloxacin degradation and real pharmaceutical wastewater treatment.The optimized 12%PCN/RGO/Bi_5O_7I displayed the highest photocatalytic activity with 92%removal of ciprofloxacin.Importantly,the COD removal efficiency and extent of mineralization of real pharmaceutical wastewater reached 66.9%and 59.8%,respectively,and the biodegradability of pharmaceutical wastewater was significantly improved.The photocatalytic mechanism of the S-scheme PCN/RGO/Bi_(5)O_(7)I van der Waals heterojunctions based on the analysis of reactive species,work function,and internal electric field was presented.This study provides fresh insights into plausible design of S-scheme van der Waals heterojunction to enhance photocatalytic redox ability.

Quantitative Analysis of Graphene Sheet Content in Wood Char Powders during Catalytic Pyrolysis

The quantitative characterization of the graphene sheet content in carbon-containing materials is arguable and has not yet been developed. The authors report on a feasible method to characterize graphene sheet content quantitatively in pyrolized carbon materials using an X-ray diffraction （XRD） spectrometer. A direct carbonation at 300℃ followed by catalytic pyrolysis （heat-treatment temperature was set at 700-1400 ℃） under a vacuum condition was used for turning wood waste into pyrolized wood char powders. The graphene content in the samples was calculated through an analysis of full width at half maximum （FWHM） of the carbon （100） crystal plane at around 42°-43° in XRD. Results showed that the FWHM and the calculated graphene sheet content of pyrolized wood char powders depended on the heat-treatment temperature, and the FWHM of wood char powder with well-developed graphene sheets （100%） was determined to be 5.0. In addition, the trend to 100% graphene sheet-contained pyrolized carbon powder was obtained at a heattreatment temperature of 2700 ℃. The resistivity of the wood char powder with 100% graphene sheets was predicted to be 0.01 Ω cm, close to our experimental data of 0.012 and 0.006 Ω cm for commercial graphite and graphene products, respectively.

Photocatalytic properties of hierarchical CuO nanosheets synthesized by a solution phase method

CuO nanomaterials were synthesized by a simple solution phase method using cetyltrimethylammonium bromide（CTAB） as a surfactant and their photocatalytic property was determined towards the visible-light assisted degradation of Reactive Black-5 dye. A detailed mechanism for the formation of CuO nanostructures has been proposed.The effect of various experimental parameters such as catalyst amount, dye concentration,p H and oxidizing agent on the dye degradation efficiency was studied. About 87% dye was degraded at p H 2 in the presence of CuO nanosheets under visible light. The enhanced photocatalytic activity of CuO nanosheets can be ascribed to good crystallinity, grain size,surface morphology and a strong absorption in the visible region. CuO is found to be a promising catalyst for industrial waste water treatment.

Ag-decorated 3D flower-like Bi_(2)MoO_(6)/rGO with boosted photocatalytic performance for removal of organic pollutants

A series of unique 3D flower-like Bi_(2)MoO_(6)(BMO)/reduced graphene oxide(rGO)heterostructured composites decorated with varying amounts of Ag nanoparticles(NPs)were fabricated.Their morphological characteristics,structural features,energy band structures and photoelectrochemical properties were systematically studied.All the Ag/BMO/rGO ternary composites(AgBGy;y=1%,2%and 3%)demonstrated greater photocatalytic activity towards efficient removal of our selected organic models[methyl orange(MO),rhodamine B(RhB)and phenol],as compared with the BMO/rGO binary composites(BG-x;x=0.25,2,4 and 5).Particularly,AgBG-2%,which was synthesized with the addition of 2 wt% rGO and 2 wt%Ag in BMO,possessed superior photocatalytic activity.The fitted rate constants(k)for the photocatalytic degradation of RhB,MO and phenol using AgBG-2% were estimated to be 0.0286,0.0301 and 0.0165 min^(-1),respectively,which were over one order of magnitude greater than those obtained using pure BMO.Several factors may contribute to the observed enhancement,including greater specific surface area,enhanced light absorption,promoted spatial separation of electronhole(e^(-)-h^(+))pairs and their suppressed recombination,especially benefiting from the synergistic effects among BMO,rGO and Ag NPs.Our work suggests that the rational design of BMO/rGO/Ag ternary composite was an effective strategy to boost the photocatalytic activity of the resulting catalyst towards the highly efficient removal of organic pollutants from water.

Enhanced carbon tetrachloride degradation by hydroxylamine in ferrous ion activated calcium peroxide in the presence of formic acid

Hydroxyl radicals(HO*)show low reactivity with perchlorinated hydrocarbons,such as carbon tetrachloride(CT),in conventional Fenton reactions,therefore,the generation of reductive radicals has attracted increasing attention.This study investigated the enhancement of CT degradation by the synergistic effects of hydroxylamine(HA)and formic acid(FA)(initial[CT]=0.13 mmol/L)in a Fe(il)activated calcium peroxide(CP)fenton process.CT degradation increased from 56.6%to 99.9%with the addition of 0.78 mmol/L HA to the CP/Fe(II)/FA/CT process in a molar ratio o f 12/6/12/1.The results also showed that the presence of HA enhanced the regeneration of Fe(II)from Fe(III),and the production of HO*increased one-fold when employing benzoic acid as the HO*probe.Additionally,FA slightly improves the production of HO*.A study of the mechanism confirmed that the carbon dioxide radical(C02·),a strong reductant generated by the reaction between FA and HO*,was the dominant radical responsible for CT degradation.Almost complete CT dechlorination was achieved in the process.The presence of humic acid and chloride ion slightly decreased CT removal,while high doses of bicarbonate and high pH inhibited CT degradation.This study helps us to better understand the synergistic roles of FA and HA for HO·and C02·^-generation and the removal of perchlorinated hydrocarbons in modified Fenton systems.

High Temperature Phase Transitions of Graphene Oxide Paper from Graphite Oxide Solution

Graphene oxide paper （GOP） can be prepared through simplified filtration of a graphite oxide solution. It possesses similar properties to graphene. In this study, the graphite oxide solution was synthesized from commercial graphite by means of Hummer＇s method. It corresponds to the dried GOP that was prepared by deposition on a cellulose filter. It is found that the mesophase of the dried graphene oxide papers obtained from the graphite was thermotropic hexagonal columnar liquid crystal. Its higher temperature transitions were found at 80 ℃, 150 ℃ and 170 ℃-180 ℃. Therefore, it could be used for thermal storage and conductive materials in the future.

Artifact analysis of a far-field coded-aperture gamma camera extended to partially coded field-of-view

Purpose Coded-aperture gamma cameras play an important role for homeland security nowadays.They have limitedfield-of-view(FOV)which is a critical parameter for many applications.The FOV can be potentially increased by extending it to the penumbra area(partially coded FOV).Methods In this study,we analyzed this artifact phenomenon based on simulating a commercial coded-aperture gamma camera.The camera uses a modified uniformly redundant array(MURA)mask with a basic pattern of rank 11.Its opening angle of the basic pattern to the detector center is 26.36◦which is the commonly used non-artifact FOV(NAFOV).In some applications,the radiation source is a far-field single-point source.Thus,we extend its FOV to 40◦by including a part of the partially coded area,which is a trade-off between the FOV and image quality.Analytical calculations and simulation studies were carried out.The system matrix was calculated using the Sidden’s algorithm.The maximum likelihood expectation maximization(MLEM)reconstruction method was employed.Projections and reconstruction results of the point source at different positions were compared.The second moment of inertia was used as thefigure of merit.Results Results show that projections have periodic similarity with a period of NAFOV,and reconstructions also have periodic artifacts,i.e.,fromθtoθ+NAFOV.Artifacts are the most serious at the edge of the NAFOV.The upper and lower artifacts are more serious than the left and right artifacts due to the difference between the horizontal centerline(tungsten)and vertical centerline(holes expect the center unit)of the mask.Conclusions For a point source with high activity,artifacts can be reduced by increasing the iteration number of the MLEM reconstruction.Even at the edge of NAFOV,the point source can be possibly reconstructed thanks to the large size of the position sensitive detector(PSD)used.The noise will significantly increase artifacts,which may lead to error locate the point source with low activity at some specific positions.