On the use of inductively coupled plasma mass spectrometry as an element specific detector for liquid chromatography: optimization of an industrial tellurium removal process
التفاصيل البيبلوغرافية
العنوان:
On the use of inductively coupled plasma mass spectrometry as an element specific detector for liquid chromatography: optimization of an industrial tellurium removal process
The current status of inductively coupled plasma mass spectrometry (ICP-MS) can be defined as a versatile element and isotope specific detection technique of high sensitivity and wide element coverage. In conjunction with this type of detector a variety of sample introduction systems is used enabling the introduction of samples in liquid, solid and gaseous form. In addition, ICP-MS instruments are increasingly being used in speciation studies especially as a detector for liquid chromatography (LC). This is demonstrated by the following representative application. A considerable part of the industrial chemicals currently produced by DSM is derived from an (amm)oxidation process on the basis of sophisticated heterogeneous catalysts in which tellurium plays an important role. A drawback of tellurium is its volatility resulting in material losses and a corresponding decay in catalytic properties. These tellurium losses show up in waste water drained at a concentration of 0.5–1.5 mg Te/l. Supply of this waste water to a central waste water purification plant leads to biological methylation of tellurium into dimethyltelluride Te(CH3)2 with an unpleasant garlic smell. Therefore a tellurium removal process was developed based on the cementation of tellurium onto iron. This process showed unacceptably low removal efficiencies when supplied with freshly drained waste water. LC–ICP-MS experiments revealed the occurrence of tellurium compounds that were only slowly converted into tellurite and tellurate. Conversion parameters and conditions were extensively studied by LC–ICP-MS experiments. Process conditions developed on a benchscale were successfully applied in a plantscale tellurium removal process. This process is capable of removing tellurium from a continuous 100 m3/h waste water supply to a concentration level of 0.01–0.03 mg Te/l.