Abstract: The carboxymethyl chitosan solution and phytic acid solution were mixed by solution blending process and then freeze-dried to prepare the composite films. The structures of the films were characterized by infrared spectroscopy, thermogravimetry analysis and scanning electron microscopy; and the adsorptions of copper, iron, and aluminum impurities in transformer oil were evaluated. The results suggested that the phytic acid did not destroy the porous structure of the composite film, and the films could effectively adsorb metal impurities in transformer oil. When the mass ratio of phytic acid to carboxymethyl chitosan was 0.4, and the adsorption temperature was 70℃, the adsorption efficiency of the porous composite film for copper, iron and aluminum in the transformer oil was 70.51%,68.99% and 87.23%, respectively.

Key words: carboxymethyl chitosan, phytic acid, transformer oil, metal, adsorption