Browsing by Subject "Copper"

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    Bioleaching as a unit operation for the recovery of copper and other metals of value from WEEE
    (2025) Maluleke, Dumisani Musa ; Harrison, Susan; Kotsiopoulos, Athanasios; Govender-Opitz, Elaine
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    Modification of the ferric chloride assay for the spectrophotometric determination of ferric and total iron in acidic solutions containing high concentrations of copper
    (Elsevier, 2012) Govender, E; Harrison, S T L; Bryan, C G
    During heap bioleaching for copper recovery, solution containing high concentrations of copper is recycled to the heaps. The commonly used 1,10-phenanthroline assay is not suitable in such situations; the presence of 6 g L−1 copper in a solution containing 50 mg L−1 ferrous iron resulted in the complete loss of the absorbance band associated with the tris(1,10-phenanthroline)iron(II) complex. The colorimetric determination of soluble ferric iron concentration using the ferric chloride assay is simple and rapid. However, it offers relatively low resolution and cannot be used to determine total iron concentrations. The detection wavelength was changed to improve resolution and the assay further modified to include an oxidation step using potassium persulfate. Therefore, both ferric and total iron concentrations can be determined rapidly using the same aliquot. There was minimal interference of copper (<5% deviation) on the modified assay with copper concentrations of 10 g L−1 and below. At greater copper concentrations the deviation increased. However, a linear relationship between absorbance and ferric iron concentration was maintained for all the solutions tested allowing correction through appropriate calibration.
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    Relationship between firewood usage and urinary Cr, Cu and As in informal areas of Cape Town
    (2013) Dalvie, Mohamed Aqiel; Africa, Algernon; Naidoo, Sivapregasen
    OBJECTIVES: The study investigated whether wood usage by informal food vendors and household residents in Cape Town results in the absorption of arsenic (As), chromium (Cr) and copper (Cu) owing to release of these metals in the burning of chromated copper arsenate (CCA)-treated wood. METHODS: The participants (N=78) selected included an equal number of food vendors and non-vendors from 2 informal settlements. All participants answered a questionnaire concerning exposure and were tested for urinary Cr, Cu and As, while the urine of 29 participants was also tested for toxic As (As(tox)). RESULTS: Multivariate analysis showed that the time spent in close proximity to the wood, as well as the quantity of wood used for cooking and for household use, was weakly positively associated with urinary levels of As, Cr and the sum of As, Cr and Cu. CONCLUSIONS: The study provides evidence that use of wood likely to contain CCA as a fuel for informal food outlets and household purposes may increase the absorption of inorganic As, Cu and Cr.