Keggin型铬取代磷钨杂多阴离子在D301R树脂上的吸附性质

Adsorption Properties of Keggin-Type Cr(Ⅲ) Substituted Heteropolytungstates on the D301R Resin

详细研究了Keggin型铬取代杂多阴离子PW11O39Cr(III)(H2O)4-(PW11Cr)在D301R弱碱性阴离子交换树脂上的吸附行为,考察了不同pH和温度对吸附容量和吸附速率的影响,根据测定的吸附动力学曲线和吸附等温线,提出了吸附所遵从的热力学和动力学模型,并计算了相应的吸附热力学函数和速率常数。结果表明,在PW11Cr稳定存在的pH范围内,PW11Cr的吸附量随溶液pH值的升高而增加,随溶液温度的升高而降低;吸附动力学符合表面过程控制的准二级吸附模型,吸附速率常数k2在298 K时为1.54×10-3g.mg-1.min-1,并随温度的升高而减小;吸附等温线符合Freundlich吸附模型,吸附热约为-37 kJ.mol-1,为物理吸附。

The adsorption behaviors of Cr （III） -substituted heteropolyanion PWu 039 Cr （III） （H2O）^4- （PW11Cr） on the D301R resin were investigated. Influences of pH and temperature upon PW11 Cr adsorption capacity and adsorption rate were also examined, respectively. The adsorption thermodynamic and kinetic equations were simulated and the corresponding parameters were calculated on the basis of adsorption kinetic curves and adsorption isotherms determined at different temperatures. The results showed that the adsorption capacities of PW11 Cr on the resin increased with pH increasing from 2 to 8 in the aqueous solution, and decreased with the increase of temperature. The adsorption kinetics followed the pseudo-second-order regime controlled by a surface process. The rate constant k2 that decreased with the increase of temperature was determined to be 1.54 × 10^-3 g ·mg^ 1 ·min^ -1 at ：298 K. The adsorption isotherms were consistent with Freundlich model and the adsorption enthalpy calculated was about -37 kJ · mol^- 1, indicating a physical adsorption process.