Phosphorus adsorption of iron oxideshumic acid compounds

Phosphorus adsorption characteristics of the goethitehumic acid (HA) compound and hematiteHA compound were studied by the batch experiments with different phosphate concentrations, pH and different ionic strengths. The results of the X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) show that the structures of iron oxides are not changed when they are coated with humic acid, while the iron oxides and humic acid generated iron oxideshumic acid compounds have larger particles and smooth surface by the H bond. These compounds have stronger adsorption capacity of phosphorus and larger specific surface area than those of the oxides. The phosphate adsorption amount of goethite-HA compound is larger than that of the hematite-HA compound, and the adsorption is multilayer. The increase of pH could inhibit the phosphate adsorption, while the increase of ionic concentration could enhance the adsorption.