Chromium leachability from blue shavings by the TCLP procedure / Edward E. Menden in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXIX, N° 1 (01/1994)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXIX, N° 1 (01/1994) . - p. 2-13 Titre : Chromium leachability from blue shavings by the TCLP procedure Type de document : texte imprimé Auteurs : Edward E. Menden, Auteur ; Frank H. Rutland, Auteur ; Waldo E. Kallenberger, Auteur Année de publication : 1994 Article en page(s) : p. 2-13 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Leachability of chromium from leather wastes is a factor of considerable environmental concern. Many factors in the tanning process such as vegetable retanning or chrome leachability in the buffer prescribed by EPA in the Toxicity Characteristic Leaching Procedure (TCLP), and presumably, therefore, in land disposal scenarios where natural forces are at work. A number of simple additions or treatments have been conducted on blue shaving in order to observe the impact upon chromium leachability in the specific conditions required by the TCLP. These observations are offered in the hope that process design and waste treatment might beneficially draw upon this knowledge for greater environmentally responsible operation. En ligne : https://drive.google.com/file/d/1JbBGYuMiIadFqKA2WWWQStT66Hq9cxoQ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8138 [article]

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Comparative study of analytical methods for hexavalent chromium / Carlos L. Nazario in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXV (Année 1990)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXV (Année 1990) . - p. 212-224 Titre : Comparative study of analytical methods for hexavalent chromium Type de document : texte imprimé Auteurs : Carlos L. Nazario, Auteur ; Edward E. Menden, Auteur Année de publication : 1990 Article en page(s) : p. 212-224 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Determination of hexavalent chromium is essential for disposal of chromium containing waste into the environment,but current methods produce ambiguity in reported results. Using five concentration levels of Cr(III) and spiking with three concentrations of Cr(VI),determinations of Cr(VI) were made using EPA** solid waste methods 7195(Coprecipitation), 7196(Colorimetric-Diphenylcarbazide), and 7197(Chelation-Extraction). The data indicate limitations in quantifying Cr(VI) in Cr(III) matrices. The Coprecipitation method was shown to be inadequate in determining the presence of Cr(VI) in Cr(III) matrices. Chelation-Extraction was able to show that one Cr(III) solution was free of any Cr(VI)contamination. For the other Cr(III)solution, the method indicated a presence of Cr(VI) but was unable to quantify the amount. Colorimetric analysis proved to be the most reliable, consistent, and informative of all three methods. It confirmed the findings of the Chelation-Extraction method and,in addition, quantified the amount of Cr(VI) present in the Cr(III) solution. En ligne : https://drive.google.com/file/d/15rr1LaP7LDuImz9aft51fLzTfctEPZns/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8661 [article]

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Comparison of chromium leachability from tannery waste usin EP toxicity and toxicity characteristic leaching procedure methods / Edward E. Menden in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXIII (Année 1988)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXIII (Année 1988) . - p. 220-231 Titre : Comparison of chromium leachability from tannery waste usin EP toxicity and toxicity characteristic leaching procedure methods Type de document : texte imprimé Auteurs : Edward E. Menden, Auteur ; Frank H. Rutland, Auteur Année de publication : 1988 Article en page(s) : p. 220-231 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : A total of 82 samples typical of leather industry solid waste materials was evaluated for chromium leachability by EPA Extraction Procedure Toxicity (EPT) and Toxicity Characteristic Leaching Procedure(TCLP) methods. These samples consisted promarily of wet blue leather trimmings and shavings, dry leather trim scrap, buffing dust and sludge. For acidic materials(pH<5) such as wet blue and dry leather wastes, TCLP extraction was 4-5 times more aggressive than EPT due to the complexing effect of acetate ion. The majority of such materials would exceed a regulatory threshold of 5.0mg/l if based on total Cr rather than CrVI. For alkaline sludge wastes, the difference in EPT and TCLP extraction was quite small, if indeed significant, and a majority of samples was below 5.0mg/l. Chromium leachability from dry leather waste was substantially lower than wet blue, despite higher solids content. Thus, leather drying appears to have a major beneficial effect. Efforts to analyze the effects of moisture level, chromium content and pH were inconclusive, and more work is planned to further clarify their role in chromium leachability. En ligne : https://drive.google.com/file/d/1EzhnP-J6CjvUYgCaLddMIa37E-recmfe/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8873 [article]

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Determination of CrVI) in tannery waste by the chelation-extraction method / Edward E. Menden in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXV (Année 1990)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXV (Année 1990) . - p. 363-375 Titre : Determination of CrVI) in tannery waste by the chelation-extraction method Type de document : texte imprimé Auteurs : Edward E. Menden, Auteur ; Frank H. Rutland, Auteur ; Waldo E. Kallenberger, Auteur Année de publication : 1990 Article en page(s) : p. 363-375 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Significant levels of hexavalent chromium have been reported in two tannery-related wastes by commercial analytical laboratories using the chelation/extraction method (EPA method 7197). Further investigation at the LIA Laboratory of such waste materials for identical sources revealed that unique trivalent chromium organocompounds were present in both. These can be erroneously identified as hexavalent chromium by virtue of the specific analytical conditions employed by the chelation/extraction procedure. Indeed, no chromium (VI) was found in either waste sample. The error in the chelation/extraction determination of chromum (VI) resulted from chromium (III) organocompounds which were directly soluble in the extraction solvent, methylisobutyl ketone. These extractable chromium (III) compounds were not specifically identified, but were found to behave identically with chromium (III) soaps and similar organochromium compounds. The distinction between chromium (VI) and extractable chromium (III) compounds was demonstrated by two changes to the chelation/extraction method. These changes help differentiate chromium states and effectively illustrate that failure to do so can lead to erroneous results with this particular analytical method. The first change was to eliminate the chelating agent that complexes hexavalent chromium and, therefore, facilitates the transfer into extracting solvent. Omitting the chelation step required for the extraction of chromium (VI) has not prevented chromum from being extracted, priving that a solvent-soluble form of chromium was present in the analyte materials. In the second change, the EPA chromium (VI) determination method was used in parallel on replicate sample groups, one of which had been treated with a powerful chromium (VI)-reducing agent. Spiked samples of several kinds also were analyzed to demonstrate that hexvalent chromium was eliminated by this reductant. Yet, significant chromium from only the waste materials still was extractable, again indicating that it was not hexavalent chromium but a solvent soluble chromium (III) compounds, including a chrome soap and a complex, and lagoon sludge water-immisciblephase with a high content of chromium (III) were introduced into water and extracted according to method 7197 and the two differentiation procedures. All three kinds of samples yielded high to complete extraction recoveries of chromium, regardless of the technique. In conclusion, the results of the aforementioned experiments indicate that the EPA chelation/extraction method for determining hexavalent chromum can definitely give false positive or erroneously high values when used on some tannery wastes. En ligne : https://drive.google.com/file/d/1O4nZWr48MagDhCGX1e2H46XSZZIgl5Rw/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8726 [article]

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Problems associated with hexavalent chromium determination / Frank H. Rutland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXV (Année 1990)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXV (Année 1990) . - p. 326-333 Titre : Problems associated with hexavalent chromium determination Type de document : texte imprimé Auteurs : Frank H. Rutland, Auteur ; Waldo E. Kallenberger, Auteur ; Edward E. Menden, Auteur ; Carlos L. Nazario, Auteur Année de publication : 1990 Article en page(s) : p. 326-333 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The ability to demonstrate that industry products, waste materials and disposal sites are free of hexavalent chronium is of crucial regulatory importance to the leather tanning industry. This requires reliable techniques to extract and detect, without alteration, small quantities of Cr6 from complex sample matrices in the presence of a large excess of Cr3 as well as other potential interferents. EPA solid waste methods 7195 (coprecipitation), 7196 (colorimetric) and 7197 (chelation/extraction) are not entirely suitable results. This report examines a number of case histories where false-positive Cr6 results were reported in tannery-related materials by independent testing laboratories, and recommends procedures to be followed in order to avoid these problems. Method 7195 is not recommended for samples with a large excess of Cr3. Methods 7196 and 7197 can provide results given reasonable care and validation. En ligne : https://drive.google.com/file/d/17LtjK6tmzj20AbcupBryPXPMg7ltrFuT/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8723 [article]

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