分子筛对水中Pb^(2+)的吸附行为及回收利用

Adsorptive property and recyling of Pb^(2+) in water with molecular sieve

以4A和13X分子筛为吸附材料,考察了分子筛投加量、废水pH值、Pb2+初始浓度和吸附时间对去除率的影响。结果表明,4A和13X分子筛投加量为0.16 g/L,废水pH为5,Pb2+初始浓度为30 mg/L时,吸附10 min后Pb2+去除率达到95%以上。通过吸附等温线和吸附动力学方程拟合,4A和13X分子筛对Pb2+的吸附过程均符合Langmuir吸附模型和Lagergren二级速率方程,计算出的饱和吸附容量Q0分别为714.3 mg/g和684.9 mg/g,二级反应速率常数k2分别为8.9×10-4g/(mg·s)和7.1×10-5g/(mg·s)。4A分子筛沉降性能较好,适宜回收;经过4次吸附-解吸仍保持88.7%的Pb2+去除率和493.2 mg/g的吸附容量,经解吸后的浓缩液中富含铅离子720.3 mg/L,富集倍数3.78,加入Na2S生成硫化物沉淀能够达到回收金属铅的目的。

With 4A and 13 X molecular sieves as adsorption materials,the influences of molecular sieve dosing quantity,pH of wastewater,initial concentration of Pb2 +and adsorption time were investigated. The result shows that,at the 0. 16 g /L of dosing quantity of 4A and 13 X molecular sieve,5 of initial pH and 30 mg /L of Pb2 +concentration,the removal rate of Pb2 +reached more than 95% after adsorbing for 10 minutes. 4A and 13 X molecular sieves were respectively conform to the Langmuir adsorption isothermal model and Lagergren secondary adsorption rate equation,saturated adsorption capacity Q0 of 714. 3 mg /g and 684. 9 mg /g,and secondary reaction rate constant k2 of 8. 9 × 10- 4g /( mg·s) and 7. 1 × 10- 5g /( mg·s) were calculated. 4A molecular sieve had better settling performance and was suitable for recycling. The removal rate of Pb2 +was still 88. 7% after four adsorption-desorption process and the adsorption capacity was still 493. 2 mg /g. The concentration of Pb2 +in the concentrate after desorption was 720. 3 mg /L and multiple of concentrate was 3. 78. Heavy metal Lead can be reclaimed by lead sulfide precipitation generated by the additional Na2 S.