硝酸钠改性5A分子筛对废水中Cr^(3+)吸附效果的影响

Preparation of Calcined 5A Zeolite Modified with Sodium Nitrate and Its Adsorption for Cr^(3+)

目的研究硝酸钠改性沸石分子筛对废水中Cr^(3+)的吸附效果影响因素,确定硝酸钠改性沸石分子筛去除Cr^(3+)的最佳工艺参数。方法以硝酸钠浸渍和煅烧制备了改性5A分子筛。通过SEM、XRD、FTIR、XPS及BET分析样品的结构和组成,研究吸附时间、溶液pH值、分子筛投加量对Cr^(3+)去除率的影响。结果经1 mol/L NaNO_(3)浸渍、673 K下煅烧的5A分子筛改性效果最好,对Cr^(3+)的最大理论吸附量较未改性5A分子筛提高了161%,吸附平衡时间缩短了73.3%。结论分子筛对Cr^(3+)的吸附等温线符合Langmuir吸附模型,吸附过程符合Lagergren准二级速率方程,改性分子筛吸附性能提高的主要原因是由于较高的介孔体积和更高的离子交换容量。

The factors affecting the adsorption efficiency on Cr^(3+)from aqueous solutions were studied to determine the optimal process parameters for the removal of Cr^(3+)by sodium nitrate modified 5A zeolite.The 5A zeolite was impregnated and calcined to prepare a sodium nitrate modified 5A zeolite.The structure and composition of the samples were characterized by SEM,XRD,FTIR,XPS and BET,and the effects of the adsorption time,pH,and dosage on the removal rate of Cr^(3+)were investigated.The results indicated that 5A zeolite modified with 1.00 mol/L NaNO_(3)and calcination at 673 K yielded the best Cr^(3+)removal efficiency,the theoretical maximum adsorption capacity of Cr^(3+)was increased by 161%,and the adsorption equilibrium time was shortened by 73.3%.The adsorption isotherm was well represented by the Langmuir isotherm model,and the adsorption process could be described by the Lagergren quasi-second-rate equation.The improved performance of the modified zeolite was mainly attributed to its relatively elevated mesopore volumes and higher ion-exchange capacity.