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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。
Adsorption properties of phosphorus by thermal modification of attapulgite were studied by static adsorption experiments. The results show that high temperature activation can increase the P adsorption capacity of attapulgite. When the calcination temperature is higher than 700 ° C, the crystal structure of attapulgite collapses and pores are clogged, resulting in a decrease in the amount of adsorption. Acid conditions are more conducive to modified attapulgite adsorption of phosphorus. When the initial concentration of phosphorus is 500 mg / L at pH 6, the amount of phosphorus adsorbed by the thermally modified attapulgite is 9.66 mg / g. Compared with the results of Langmuir isotherm, the Freundlich isotherm equation can better describe the adsorption of phosphorus by the thermally modified attapulgite, which indicates that the adsorption takes place on the heterogeneous adsorbent. Thermodynamic studies show that the modified attapulgite is a spontaneous endothermic process for phosphorus adsorption, belonging to the physical adsorption. Adsorption kinetics studies show that modified attapulgite phosphorus adsorption process in line with the quasi-second-order kinetic model.