The character of phosphorous adsorption in water on different substrates

Phosphorus adsorption isotherms and adsorption kinetics of steel slag,activated carbon,natural zeolite and coarse sand were studied,and the effect of pH value on phosphorus adsorption was evaluated.The results showed that,the adsorption isotherms of activated carbon,natural zeolite and sand qualified Freundlich equation(r0.9),and steel slag fitted Langmuir equation.The adsorptive capacity was ranged as steel slagactivated carbonzeolite coarse sand.The adsorption mechanisms of zeolite and coarse sand were physical adsorption,and that of slag was chemical adsorption.Phosphorus adsorption by activated carbon was physical adsorption firstly,and then chemical adsorption.Phosphorus adsorption kinetics of the four kinds of substrates can be described as Elovich equation and two-constant rate equation.The effect of pH value on the steel slag adsorption capacity was indistinct.The adsorbility of zeolite under the condition of acid and alkalescence were the same.When pH value was 3 to 13,the adsorption capacity of activated carbon remained at 190 mg/kg.The adsorption capacity of coarse sand was maximum when pH was 3.According to our research,steel slag was the optimal substrate for phosphorus removal in constructing land treatment system.