Storage stability and oxidization of stable-oxidation-poly-Si-Fe (SOPSF) coagulant

A new inorganic coagulant, stable-oxidation-poly-Si-Fe (SOPSF) was prepared by copolymerization and was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and redox potential meter. Storage stability and oxidation behavior of SOPSF in treating synthetic humic acid (HA) water samples were explored. The results showed that SOPSF appeared to be a crystal-like structure having a smooth appearance in SEM which prevented connection with each other, and was showed to be a fully extending tree-like structure in TEM. Like poly-Si-Fe (PSF), SOPSF gave stronger oxidization with redox potential (RP) value of 766 mV than Polyferric aluminum with RP of 285 mV, and the declines of their RP values were very small with the decreasing of concentration. SOPSF gave different longer storage time than PSF under different given Fe level ranges at 6 or 25°C, and compared to PSF; the lower the Fe concentration, the better was the SOPSF storage stability. SOPSF oxidization changed the molecular structure of some HA, thus modifying the surface nature of some HA and the interface nature between HA and water sample, which improved HA adsorption on Kaolin. SOPSF oxidization played a key role in removing organic matters, especially dissolved organic matters, during coagulation process.