Adsorption Characteristic of Steel Slag Haydite for Phosphorus Removal from Wastewater

Slag haydite made from steel slag and clay was used for phosphate adsorption, and adsorption characteristic was studied. Results showed that the uptake of phosphate was facilitated for pH 3-8, the adsorption process fitted with pseudo-second-order model and intra-particle diffusion model, and the equilibrium time was about 3h. Isotherm adsorption data on slag haydite were fitted by both the Freundlich and Langmuir models. It was found that the data follows the Langmuir model better, and the maximum adsorption capacity increased from 1.17mg·g-1 to 2.42mg·g-1 as temperature rose from 20°C to 40°C. Thermodynamic parameters G0, H0 andS0 showed that the adsorption was spontaneous, endothermic and entropy increase process and increasing temperature was favorable.