Preparation and characterisation of carboxymethyl-chitosan/sodium phytate composite membranes for adsorption in transformer oil

Adsorption of metal impurities from transformer oil was studied using a novel porous membrane. A solution of N, O‑carboxymethyl‑chitosan (CMC) and sodium phytate (SP) was blended to prepare a novel porous membrane for the metal impurities adsorption from transformer oil. The chemical structure of the membranes was characterised by their FTIR spectra, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and video camera observations. The effects of the SP content of the membrane, contact time, and contact temperature on adsorption of copper, iron, and aluminium impurities were studied. The FTIR spectra and thermogravimetric curves of the membranes indicated good compatibility between CMC and SP. The SEM and video camera observations suggested that CMC-SP composite membranes had a mature, porous structure. The experimental results showed that the SP content significantly affected the adsorption capacity of a CMC membrane. The maximum adsorption percentages of elemental copper, iron, and aluminium were 88.12%, 82.35%, and 80.36% when the SP ratio was 80% at 60 °C.