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 (r>0.9), and steel slag fitted Langmuir equation. The adsorptive capacity was ranged as steel slag>activated carbon>zeolite >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.%选取钢渣、活性炭、天然沸石、粗砂4种基质,结合矿物成分分析研究其对磷的等温吸附特征和吸附动力学过程,并考察pH值对其吸附磷的影响.结果表明:活性炭、天然沸石、粗砂的等温吸附特征与Freundlich方程拟合较好(r＞0.9);而钢渣更符合Langmuir方程.其吸附能力大小为:钢渣＞活性炭＞沸石＞粗砂.沸石、粗砂对磷酸盐的吸附以物理吸附为主,钢渣以化学吸附为主,而活性炭在前期以物理吸附为主,后期则以化学吸附为主.Elovich方程和双常数速率方程能较好的反映4种基质对磷的吸附动力学特征.pH值的变化对钢渣的吸附性影响不大,沸石在酸性及弱碱性条件下对磷的吸附性相当,活性炭在pH3～13吸附量维持在190mg/kg左右,粗砂在pH3时吸附量达最大,综合而言,在土地处理系统的实际应用中,选取钢渣可获取最佳的除磷效果.
展开▼
