4A和13X分子筛去除水中重金属Cd^(2+)及其吸附性能研究

4A and 13X molecular sieves used to remove heavy metal ion Cd^(2+) from water and their adsorption property

以4A和13X分子筛为吸附材料,考察废水pH值和Cd2+初始浓度等对Cd2+去除率的影响,并研究了分子筛对Cd2+的吸附性能。结果表明,4A和13X分子筛投加量为0.16g/L、废水pH值为5、Cd2+浓度为20mg/L时,Cd2+去除率达到95%以上;分子筛对Cd2+的去除机理以离子交换吸附为主,交换出来的Na+与分子筛吸附的Cd2+摩尔浓度比为2;在吸附热力学和动力学方面,4A和13X分子筛均符合Langmuir吸附等温模型和Lagergren二级速率方程,计算的饱和吸附容量Q0分别为150.15、163.67 mg/g,二级反应速率常数K2分别为2.45×10-3、3.96×10-4 g/(mg·s)。该吸附反应是一种单分子层反应速度较快的化学吸附过程。

With 4A and 13X molecular sieves as adsorption materials ,the effects of the pH value of waste water and the initial concentration of Cd2＋ on Cd2＋ removal rate were investigated and the sieves’ adsorption of Cd2＋ was studied .The results show that ,at the 0 .16g/L of dosing quantity of 4A and 13X molecular sieves ,5 of initial pH and 20 mg/L of Cd2＋ concentration ,Cd2＋ removal rate reaches 95% or more .The primary mechanism of Cd2＋ removal by molecular sieves is ion exchange adsorption .The molar concentration ratio between exchanged Na ＋ and Cd2＋ adsorbed by the sieves is 2∶ 1 ,In adsorption thermodynamics and dynamics ,4A and 13X molecular sieves conform to the Langmuir adsorption isothermal model and Lagergren secondary rate equation ,respectively .The sat-urated adsorption capacities are 150 .15 mg/g and 163 .67 mg/g ,and the secondary reaction rate con-stants are 2 .45 ＆#215; 10 -3 g/（mg ＆#183; s） and 3 .96 ＆#215; 10-4 g/（mg ＆#183; s） ,respectively .It is also found that the adsorption reaction is a fast single molecular layer chemical process .