Arsenic (As) is toxic to human and is often found in drinking water in India and Bangladesh, due to the natural abundance of arsenides ores. Different removal procedures such as precipitation, ...sorption, ion exchange and membrane separation have been employed for removal of As from contaminated drinking water (CDW), however, there is a critical need for low-cost economically viable biochar modification methods which can enhance As sorption. Here we studied the effectiveness of zero-valent iron (ZVI)-biochar complexes produced by high temperature pyrolysis of biomass and magnetite for removing As5+ from CDW. Batch equilibration and column leaching studies show that ZVI-biochar complexes are effective for removing As5+ from CDW for the studied pH range (pH ∼7–7.5) and in the presence of competing ions. XPS As 3d analysis of ZVI-biochar complexes exposed to As5+ in the batch and column studies show primarily As3+, indicating simultaneous oxidation of Fe° to Fe3+ and reduction of As5+ to As3+. SEM-EDS and XRD analyses show isomorphous substitution of As3+ for Fe3+ in neo-formed α/γ-FeOOH on biochar surfaces, which is attribute to co-precipitation. This study also demonstrates the efficacy of pyrolyzing biomass with low-cost iron ores at 900 °C to rapidly produce ZVI-biochar complexes, which have potential to be used for treatment of As CDW.
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•Zero-valent iron (ZVI) biochar complexes are effective for As5+ removal from water.•Co-pyrolysis of low cost iron ore and biomass can produce ZVI biochar complexes.•Simultaneous oxidation of Fe° to Fe3+ and reduction of As5+ to As3+ occurred.•As3+ sorption attributed to isomorphous substitution of As3+ for Fe3+ in α/γ-FeOOH.•ZVI-biochar complex developed in this study can mitigate As contamination risk.
Biochar applications have been shown to increase crop yields on acidic and low activity soils in the tropics but fewer positive yield responses have been reported for temperate soils. We hypothesized ...that even without a yield response, applying biochar to a Midwestern Mollisol could improve soil quality and plant nutrient availability because of the carbon it supplies and its conditioning effect. Eighteen small field plots (23.7m2) on a glacial-till derived soil were established by incorporating 0 to 96Mgha−1 of hardwood biochar to a depth of 30cm. Several soil quality indicators, plant nutrient availability, uptake, and yield of two consecutive maize (Zea mays L.) crops were monitored. Biochar application significantly increased soil pH, readily available water (RAW) content (defined as volumetric water available between −10kPa and −100kPa) and soil organic C (SOC). It decreased bulk density (BD), but had no consistent effect on soil infiltration rates, CEC, or nutrient uptake. Biochar application did increase grain yield during the first year by 11 to 55% following very high stover application rates (3.5× the typical amount), presumably because biochar mitigated adverse effects of allelochemicals released from the decomposing maize residue. There was no detectable biochar effect on maize yield during the second year when the crop was limited by severe drought.
•Biochar may mitigate adverse effects of allelochemicals from decomposing residue on maize yields.•Biochar application decreased soil bulk density and increased surface volumetric water content.•High rates of biochar did not adversely affect plant nutrition or corn grain yields.
The treatment of flue gases from power plants and municipal or industrial wastewater using electron beam irradiation technology has been successfully demonstrated in small-scale pilot plants. The ...beam energy requirement is rather modest, on the order of a few MeV; however, the adoption of the technology at an industrial scale requires the availability of high beam power, of the order of 1 MW, in a cost effective way. In this article we present the design of a compact superconducting accelerator capable of delivering a cw electron beam with a current of 1 A and an energy of 1 MeV. The main components are an rf-gridded thermionic gun and a conduction cooledβ=0.5ellipticalNb3Sncavity with dual coaxial power couplers. An engineering and cost analysis shows that the proposed design would result in a processing cost competitive with alternative treatment methods.
The higher efficiency of superconducting radio-frequency (SRF) cavities compared to normal-conducting ones enables the development of high-energy continuous-wave linear accelerators (linacs). Recent ...progress in the development of high-qualityNb3Snfilm coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. A possible use of conduction-cooled SRF linacs is for environmental applications, requiring electron beams with energy of 1–10 MeV and 1 MW of power. We have designed a 915 MHz SRF linac for such an application and developed a prototype single-cell cavity to prove the proposed design by operating it with cryocoolers at the accelerating gradient required for 1 MeV energy gain. The cavity has a∼3μmthickNb3Snfilm on the inner surface, deposited on a∼4mmthick bulk Nb substrate and a bulk∼7mmthick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three Gifford-McMahon cryocoolers. The rf tests of the conduction-cooled cavity, performed at General Atomics, achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date and meet the requirements for a 1 MeV energy gain.
Up to half of the world's drylands have degraded, dysfunctional soils that lower success rates of restoration efforts to reestablish lost vegetation. Because soil amendments of organic matter have ...the potential to improve multiple ecosystem functions and overall soil health, we added a mulch of whole mesquite (Prosopis velutina) branches—both alone and in combination with 3 and 6 cm of compost—to a degraded semiarid rangeland. We then measured effects of these organic amendments on a suite of soil health indicators as well as plant cover and abundance. We found that surface applications of these amendments improved several indicators of soil health after two summer growing seasons. Soil temperature decreased and soil moisture increased in all treatments with organic amendments. However, during drier times of the year and in response to smaller rain events, mulch alone increased soil moisture more so than when combined with compost. As expected, total soil nitrogen was greatest with compost addition. Soil organic carbon, water‐stable aggregate size, and microbial abundance did not respond significantly to any treatment. Mesquite mulch increased native plant cover and abundance when applied without compost and increased plant cover when combined with 3 cm of compost, but it did not increase plant abundance or cover when combined with 6 cm of compost. Collectively, these results suggest that a thin layer of compost—but particularly woody branches used as mulch—can improve success rates of revegetation in dryland ecosystems by moderating the soil microclimate.
Accelerators for Discovery Science and Security applications Todd, A.M.M.; Bluem, H.P.; Jarvis, J.D. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
05/2015, Letnik:
350, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Several Advanced Energy Systems (AES) accelerator projects that span applications in Discovery Science and Security are described. The design and performance of the IR and THz free electron laser ...(FEL) at the Fritz-Haber-Institut der Max-Planck-Gesellschaft in Berlin that is now an operating user facility for physical chemistry research in molecular and cluster spectroscopy as well as surface science, is highlighted. The device was designed to meet challenging specifications, including a final energy adjustable in the range of 15–50MeV, low longitudinal emittance (<50keV-psec) and transverse emittance (<20πmm-mrad), at more than 200 pC bunch charge with a micropulse repetition rate of 1GHz and a macropulse length of up to 15μs. Secondly, we will describe an ongoing effort to develop an ultrafast electron diffraction (UED) source that is scheduled for completion in 2015 with prototype testing taking place at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). This tabletop X-band system will find application in time-resolved chemical imaging and as a resource for drug–cell interaction analysis. A third active area at AES is accelerators for security applications where we will cover some top-level aspects of THz and X-ray systems that are under development and in testing for stand-off and portal detection.
Zusammenfassung
Bei der derzeitigen Erschließung von alternativen und erneuerbaren Energiequellen finden in erster Linie Biomasse und Windkraft Beachtung. Im Vergleich dazu bietet die Nutzung der ...Wasserkraft in der Form von Kleinwasserkraftwerken nach wie vor ein sehr großes Ausbaupotential. Dieses ist jedoch aus ökologischen, ökonomischen oder gesellschaftlichen Gründen in seiner Akzeptanz begrenzt. In dieser Arbeit wird eine neue Technologie, das Wasserwirbelkraftwerk, vorgestellt und im Hinblick auf die potentielle elektrische Leistungsabgabe bewertet. Bisherige Betriebserfahrungen haben gezeigt, dass der neue Kraftwerkstyp nur einen geringen Eingriff in Bach- und Flusslandschaften darstellt und sich positiv auf deren Bioaktivität auswirkt. Des Weiteren können solche Kraftwerke schon bei sehr geringer Fallhöhe wirtschaftlich betrieben werden.
Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate: formate lyase and the fermentative lactate dehydrogenase, ...gave rise spontaneously to a chromosomal mutation that restored its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor, strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1 mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence in E. coli of a novel succinic acid:acetic acid:ethanol fermentation pathway
Reactive nitrogen (Nr) is a term used to describe non-nitrogen gas (non-N2) forms of nitrogen (N) in the biosphere. It causes major pollution problems when it occurs in excess, and it has many ...sources, including fertilizers used in production agriculture. Currently there is no on-the-go soil nitrate sensor that could guide the application of the optimal amount of fertilizer, which often varies significantly within a field. We report for the first time nitrate-in-soil measurements performed on moving soil samples at concentration levels relevant for fertilizer application. An infrared emission technique called transient infrared spectroscopy (TIRS) was tested on soil samples spiked with different nitrate concentrations in the parts-per-million range and moving at a velocity of 2.6 m/s (5.8 miles per hour) in the laboratory. The TIRS Fourier transform infrared (FT-IR) spectra were modeled by partial least squares and produced a standard error of cross-validation (SECV) of 6.3 parts per million (ppm) N and an R2 of 0.938 for 512-scan spectra. These results are compared to those using fewer TIRS scans and to those from photoacoustic spectroscopy (PAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements on stationary samples. TIRS 128-, 32-, and 8-scan spectra yielded SECVs of 11.2, 11.4, and 18.4 ppm N and R2 values of 0.800, 0.831, and 0.583, respectively. The PAS and DRIFTS measurements produced SECVs of 12.4 and 9.0 ppm N and R2 values of 0.766 and 0.876, respectively.
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