Kinetic and Thermodynamic Studies of Adsorption of Phosphate on Steel-Slag Filter Material

Slag filter material made from steel slag and clay was used for phosphate adsorption, and adsorption characteristic was studied by batch experiments. Results showed that the uptake of phosphate on slag filter material at different temperature fitted with pseudo-second-order model, and the activation energy was more than 40kJ/mol. In addition, isotherm adsorption data on slag filter material followed the Langmuir model well, and the maximum adsorption capacity at 20°C, 30°C and 40°C were 1.166, 1.826 and 2.422mg/g, respectively. Thermodynamic parameters G0, H0 andS0 showed that the adsorption was spontaneous, endothermic and entropy increase process and chemical adsorption was dominant for phosphate uptake.