Equilibrium and kinetic properties of a fast iminodiacetate based chelating ion exchanger and its incorporation in a FIA-ICP-AES system

Abstract

The equilibrium and kinetic properties of an iminodiacetate (IDA) based chelating ion exchanger with a crosslinked agarose, Novarose™, as support has been investigated. The second and third acidity constants and some complexation constants of the ligand were determined for adsorbents with metal binding capacities of 140, 55 and 18 μmol ml −1, respectively. The adsorbent of medium capacity showed fast adsorption and desorption of Cu(II), Cd(II), Ni(II) and Ca(II) both in the batch and column mode. It was found to be about 50 times faster than Chelex-100 (50–100 mesh) in accumulation of these metal ions in the batch mode. Studies of the adsorbent in a flow system, using a 5 mm × 6 mm i.d. column, indicated quantitative accumulation of Cu(II), Cd(II), and Ni(II) at volumetric flow rates up to 110 ml min −1. Linear calibration curves with r > 0.999 and signal enhancement factors up to 1300 were obtained. Preconcentration by a FIA system connected to an ICP-AES instrument will make simultaneous measurement of ultratrace concentrations of a number of metal ions possible within reasonable cycle times due to the high flow rates which can be used with the adsorbent. Trace amounts of cadmium and copper in tap water were determined successfully at 60 ml min −1. However, copper and nickel in tap water are strongly complexed and do not accumulate quantitatively even at low flow rates. Hence a sample pretreatment is needed. Copper was completely adsorbed after UV-treatment of the sample.