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    Determination of total and fluoride bound aluminium in tea infusions by ion selective electrode and flame atomic absorption spectrometry
    (Marcel Dekker Inc, 2000) Erdemoglu, SB; Türkdemir, H; Güçer, S
    Speciation of metallic compunds is important especially for their bioavailability. In this present study fluoride bound aluminium species were determined in tea infusion. Total aluminium was measured using name atomic absorption spectrometry (FAAS). Free fluoride and total fluoride were measured by fluoride selective ion electrode (FISE) with the assistance of TISAB buffer solution used for adjustment of pH and total ionic strength, and ALCOA buffer solution which decomposes all of the Al-fluoride complexes in solution. During the studies, the effects of pH and time on the formation of Al-F complexes and interference of some metal ions found in tea infusion such as Al3+, Mg2+, Fe2+, Fe3+ and Mn2+ on the concentration of free fluoride were investigated. The concentration of each Al-fluoride complexes in tea infusion were determined indirectly by calculation using pF-Mole Fraction Diagram. It was found that 1.13+/-0.15 mg l(-1) of 12.00+/-0.86 mg l(-1) total aluminium is fluoride bound aluminium, which means that approximately 10% of total aluminium in tea infusion is complexed with fluoride.
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    Electrochemical oxidation of textile dye indigo
    (Wiley, 2005) Dogan, D; Türkdemir, H
    Electrochemical methods are being used increasingly as an alternative treatment process for the remediation of textile wastewaters. This study focused mainly on the colour removal and chemical oxygen demand (COD) reduction of vat textile dye (CI Vat Blue 1: indigo) from its aqueous solution by electrochemical oxidation. The process was carried out in a batch-type divided electrolytic cell under constant potential using a Pt cage as anode and Pt foil as cathode. Operating variables such as supporting electrolyte, pH, ultrasonification and treatment time were investigated to probe their effects on the efficiency of the electrochemical treatment. Colour removal was estimated by monitoring the disappearance of the absorbance peak at 681.5 nm. It was found that in acidic conditions the electrolysis was more efficient. At pH 1, an NaCl concentration of 0.24 mol dm(-3), a dyeing solution concentration of 0.1% (w/v) and a period of 90 min of electrolysis, there was almost 100% colour removal and 60% reduction in COD. Voltammetric and IR investigations demonstrated that partial degradation of dye was achieved. The experimental results indicate that this electrochemical method could effectively be used as a pretreatment stage before conventional treatment. (c) 2005 Society of Chemical Industry.