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S. Fink - One of the best experts on this subject based on the ideXlab platform.

  • OXALATE MASS BALANCE DURING Chemical Cleaning IN TANK 6F
    2011
    Co-Authors: M. Poirier, S. Fink
    Abstract:

    The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed Chemical Cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the Chemical Cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during Chemical Cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following Chemical Cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the Chemical Cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

  • ANALYSIS OF SAMPLES FROM TANK 5F Chemical Cleaning
    2011
    Co-Authors: M. Poirier, S. Fink
    Abstract:

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed Chemical Cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the Chemical Cleaning. SRS personnel collected liquid samples during Chemical Cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following Chemical Cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the Chemical Cleaning process. The conclusions from this work are: (1) With the exception of iron, the dissolution of sludge components from Tank 5F agreed with results from the actual waste demonstration performed in 2007. The fraction of iron removed from Tank 5F by Chemical Cleaning was significantly less than the fraction removed in the SRNL demonstrations. The likely cause of this difference is the high pH following the first oxalic acid strike. (2) Most of the sludge mass remaining in the tank is iron and nickel. (3) The remaining sludge contains approximately 26 kg of barium, 37 kg of chromium, and 37 kg of mercury. (4) Most of the radioactivity remaining in the residual material is beta emitters and {sup 90}Sr. (5) The Chemical Cleaning removed more than {approx} 90% of the uranium isotopes and {sup 137}Cs. (6) The Chemical Cleaning removed {approx} 70% of the neptunium, {approx} 83% of the {sup 90}Sr, and {approx} 21% of the {sup 60}Co. (7) The Chemical Cleaning removed less than 10% of the plutonium, americium, and curium isotopes. (8) The Chemical Cleaning removed more than 90% of the aluminium, calcium, and sodium from the tank. (9) The Cleaning operations removed 61% of lithium, 88% of non-radioactive strontium, and 65% of zirconium. The {sup 90}Sr and non-radioactive strontium were measured by different methods, and the differences in the fraction removed are not statistically significant. (10) Chemical Cleaning removed 10-50% of the barium, chromium, iron, magnesium, manganese, and silicon. (11) Chemical Cleaning removed only {approx}1% of the nickel.

Samuel D. Fink - One of the best experts on this subject based on the ideXlab platform.

  • Oxalate Mass Balance During Chemical Cleaning in Tank 5F
    2011
    Co-Authors: Michael R. Poirier, Samuel D. Fink
    Abstract:

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed Chemical Cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the Chemical Cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during Chemical Cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following Chemical Cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the Chemical Cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  • Analysis of solids remaining following Chemical Cleaning in tank 6F
    2010
    Co-Authors: Michael R. Poirier, Fernando F. Fondeur, David M. Missimer, Michael E. Summer, Samuel D. Fink
    Abstract:

    Following Chemical Cleaning, a solid sample was collected and submitted to Savannah River National Laboratory (SRNL) for analysis. SRNL analyzed this sample by X-ray Diffraction (XRD) and scanning electron microscopy (SEM) to determine the composition of the solids remaining in Tank 6F and to assess the effectiveness of the Chemical Cleaning process.

Long D. Nghiem - One of the best experts on this subject based on the ideXlab platform.

  • Membrane fouling and Chemical Cleaning in water recycling applications
    Desalination, 2010
    Co-Authors: Monique Beyer, Burkhard Lohrengel, Long D. Nghiem
    Abstract:

    Abstract Fouling and subsequent Chemical Cleaning are two important issues for sustainable operation of nanofiltration (NF) membranes in water treatment and reuse applications. Fouling strongly depends on the feed water quality, especially the nature of the foulants and ionic composition of the feed water. Consequently, appropriate selection of the Chemical Cleaning solutions can be seen as a critical factor for effective fouling control. In this study, membrane fouling and Chemical Cleaning under condition typical to that in water recycling applications were investigated. Fouling conditions were achieved over approximately 18 h with foulant cocktails containing five model foulants namely humic acids, bovine serum albumin, sodium alginate, and two silica colloids in a background electrolyte solution. These model foulants were selected to represent four distinctive modes of fouling: humic acid, protein, polysaccharide, and colloidal fouling. Three Chemical Cleaning solutions (alkaline solution at pH 11, sodium dodecyl sulphate (SDS), and a combination of both) were evaluated for permeate flux recovery efficiency. The results indicated that with the same mass of foulant, organic fouling was considerably more severe as compared to colloidal fouling. While organic fouling caused a considerable increase in the membrane surface hydrophobicity as indicated by contact angle measurement, hydrophobicity of silica colloidal fouled membrane remained almost the same. Furthermore, a mechanistic correlation amongst Cleaning efficiency, characteristics of the model foulants, and the Cleaning reagents could be established. Chemical Cleaning of all organically fouled membranes by a 10 mM SDS solution particularly at pH 11 resulted in good flux recovery. However, notable flux decline after SDS Cleaning of organically fouled membranes was observed indicating that SDS was effective at breaking the organic foulant—Ca 2+ complex but was not able to effectively dissolve and completely remove these organic foulants. Although a lower permeate flux recovery was obtained with a caustic solution (pH 11) in the absence of SDS, the permeate flux after Cleaning was stable. In contrast, the Chemical Cleaning solutions used in this study showed low effectiveness against colloidal fouling. It is also interesting to note that membrane fouling and Chemical Cleaning could permanently alter the hydrophobicity of the membrane surface.

Zhang Run-ping - One of the best experts on this subject based on the ideXlab platform.

  • Research on standard processes of Chemical Cleaning of stone relics
    Sciences of conservation and archaeology, 2012
    Co-Authors: Zhang Run-ping
    Abstract:

    This research was conducted as part of the National Technology Support Project 'Research on the Cleaning of harmful surface residues in the stone grotto',and is prepared as a draft of 'Standard Chemical Cleaning procedures to clean surface pollution on immovable stone relics'.In order to get an extensive and in-depth understanding of the subject,the experiences with laboratory Chemical Cleaning and on-site Chemical Cleaning at Yungang grotto is discussed.International Chemical Cleaning technique requirements and processes were reviewed.Also included were preliminary field investigations,criteria for selection of cleaners,glue and attachment techniques,evaluation of results,laboratory research and on-site tests.Positive and negative factors related to the Chemical Cleaning of stone relics are discussed.This work,therefore,provides useful information for the development of standards for Chemical Cleaning of stone relics.

Zhang Da-quan - One of the best experts on this subject based on the ideXlab platform.