Synthesis, characterization, and application of m-phenylendiamine-modified Amberlite XAD-4 resin for preconcentration and determination of metal ions in water samples.

A new chelating resin is prepared by coupling Amberlite XAD-4 (Serva, Heidelberg, New York) with m-phenylendiamine through an azo spacer, characterized (by elemental analysis, infrared, and thermogravimetric analysis) and studied for preconcentrating nickel(II), cobalt(II), zinc(II), copper(II), and chromium(III) using flame atomic absorption spectrometry for metal monitoring. The optimum pH values for sorption of the above-mentioned metal ions were 8.5, 8.5, 6.5, 6.5, and 5.5, respectively. The resin was subjected to evaluation through batch binding and column chromatography of the mentioned metal ions. Quantitative desorption occurred instantaneously with 0.5 M HNO3. Various flowrates of sorption and desorption of nickel(II) have been studied. The sorption capacity was found to be 3.89, 3.27, 2.96, and 3.44 mmol/g of resin for cobalt, copper, zinc, and nickel, respectively. The chelating resin can be reused for 10 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of >98% was obtained for all the metal ions, with 0.5 M HNO3 as the eluting agent. The method was applied for determination of metal ions from an industrial wastewater sample.