热改性凹凸棒石吸附磷的试验研究

摘要

通过静态吸附试验研究热改性凹凸棒石对磷的吸附特性.结果表明高温活化手段可以提升凹凸棒石对磷的吸附量.当煅烧温度高于700℃时,凹凸棒石的晶体结构坍塌,微孔被堵塞,导致吸附量减少.酸性条件更有利于改性凹凸棒石吸附磷.当pH值为6,磷的初始质量浓度为500 mg/L时,热改性凹凸棒石对磷的吸附量为9.66 mg/g.与Langmuir等温方程拟合结果相比较,Freundlich等温方程能更好的描述热改性凹凸棒石对磷的吸附过程,表明该吸附过程是发生在结构为非均相的吸附剂之上的.热力学研究表明,改性凹凸棒石对磷吸附过程是自发的吸热过程,属于物理吸附.吸附动力学研究表明,改性凹凸棒石对磷吸附过程符合准二级动力学模式.%Characteristics of phosphorus adsorption onto thermal modified palygorskite were studied by static adsorption experiments. The results showed that calcination was able to enhance the phosphorus adsorption capacity of the thermal modified palygorskite. When the calcination temperature was above 700, the crystal structure of palygorskite was collapsed and the micro holes were blocked, leading to the adsorption capacity of phosphate onto thermal modified palygorskite reduce. Acid conditions were favor to the adsorption of phosphate onto thermal modified palygorskite. When pH was 6 and the initial concentration of P was 500 mg/L, theadsorption capacity was 9.66 mg/g. Compared with Langmuir isotherm, Freundlich isothermprovided a better description of the adsorption process, indicating that the adsorption process of phosphate onto thermal modified palygorskite was heterogeneous. The thermodynamic study showed that the adsorption process of phosphorus was spontaneous and endothermic process, which belonged to physical adsorption. Kinetic studies indicated that the adsorption of phosphate onto thermal modified palygorskite can be fitted by pseudo-second-order kinetic model very well.