FTIR-spectrum measurements
The DTPINa solution was slowly added into metal ions (Cu2+,Fe2+, Pb2+and Zn2+) solutions of 10−2mol/L in weak acid medium until no more precipitate was generated to prepare metal-collector complexes. The compounds were washed by distilled water for three times to wipe off redundant collector and metal ions attached on the compounds surface and dried at room temperature in a vacuum drying oven for 48 h.The IR spectra of metal-collector complexes were obtained by the using of a FTIR Avatar model 360 from Nicolet DIR Nicolet accessory (Nicolet spectrometer, AVATAR360, USA), and the dry KBr particles were used as the background.