The separation of mercury from aqueous HgCl2 solutions by onion skins (outermost coat) was studied both experimentally and theoretically. The distribution equilibria were measured by the batchwise method. The experimental results revealed that onion skin is a useful material for separating mercury from aqueous systems. The distribution data obtained at 25°C were analyzed by using the theory based on the law of mass action. The separation of dissolved mercury by onion skins was found to be a process accompanied by an ion-exchange reaction of the cationic complex HgCl+ and an adsorption of the neutral complex HgCl2. The equilibrium constants of the ion-exchange and adsorption processes at 25°C and the mercury-binding capacity of onion skins were determined. Further, it was found that the distribution equilibrium of mercury is comparatively insensitive to temperature.

Separation of Mercury from Aqueous Mercuric Chloride Solutions by Onion Skins

Various spectrophotometric methods for the analysis of metal ions viz, As, Sb, Bi, Cd, Cr, Pb, Μη, Hg, and Zn are reviewed. The literature of the last 10 years on the spectrophotometric determination of these metal ions has been incorporated and the data are summarised in the Table.

Solvent extraction and spectrophotometric methods for the determination of some toxic metal ions

The method is based on the extraction of the ion-association complex of [HgI4]2− with Malachite Green or Methyl Violet into benzene and toluene respectively. The Malachite Green extract has maximum absorbance at 630 nm. A single extraction is adequate for quantitative extraction. The method is applicable to determination of trace Hg(II) in industrial effluents.

Extractive spectrophotometric determination of microgram amounts of mercury as a ternary complex with iodide and a triphenylmethane dye

1,2,3-Cyclohexanetrione-1,2-dioxime-3-thiosemicarbazone (CTDT), produces coloured complexes with zinc and cadmium ions in basic medium. The yellow colour obtained has been used to develop spectrophotometric methods for zinc and cadmium in the concentration range 1.30-8.50 μg ml−1 of zinc and 1.20-6.50 μg ml−1 of cadmium.



A new method for the determination of zinc and cadmium in mixtures is proposed for concentrations between 0.5-6.0 μg ml−1 and 0.8-5.5 μg ml−1 by first derivative spectrophotometry and between 0.5-6.0 μg ml−1 and 0.8-5.5 μg ml−1 by second derivative spectrophotometry.

Spectrophotometric Determination of CD(II) and Zn(II) with 1,2,3‐Cyclohexanetrione‐1,3‐Dioxime‐2‐Thiosemicarbazone. Simultaneous Determination by first and Second Derivative

Extraction-spectrophotometric determination of traces of mercury with Brilliant Green

水銀薄膜電極を用いたく形波アノーディックストリッピングボルタンメトリーにより高濃度亜鉛(10-2M)の共存下でカドミウムの定量を試みた.0.5Mアンモニア系緩衝溶液(pH9)の支持電解質中で,-1.0VvsSCEで15分間前電解し,-1.0～0.0VvsSCEで掃引速度30mV/sでカドミウムの溶出曲線を記録した.10-2M亜鉛(II)の共存下でもカドミウム(II)濃度とピーク電流値の関係は,カドミウム9×10-9～9×10-8Mの間で原点を通る良好な直線となり,カドミウム(II)5.8×10-8Mを含む溶液での相対標準偏差は4.3%であった.クロム(VI)がカドミウムの定量をわずかに妨害したが,その他の金属イオンはほとんど妨害しなかった.又,硝酸イオン,塩化物イオン及び酢酸イオンは0.1Mまでの共存が許容されたが,硫酸イオンはわずかに妨害した.本法を亜鉛及び亜鉛化合物中のカドミウムの定量に応用し,満足できる結果が得られた.

Tsugikatsu Odashima

Papers

Extraction-spectrophotometric determination of traces of mercury with Brilliant Green

Determination of traces of cadmium in zinc and its compounds by square-wave anodic stripping voltammetry.