CPAM对疏浚淤泥中镉解吸行为的影响

Effects of CPAM on adsorption and desorption characteristics of Cd in dredged sludge

探讨了阳离子聚丙烯酰胺(CPAM)离子度、分子量及加入量对疏浚淤泥中镉(Cd)吸附与解吸行为的影响及机理。结果表明:当淤泥初始Cd浓度为0.5μg/L时,加入CPAM静置沉降后,上清液中Cd浓度基本小于0.1μg/L,与未加CPAM自然沉降后上清液中的Cd浓度基本一致;而在真空抽滤条件下,滤液中Cd浓度最高可达到0.35μg/L,约64%的Cd脱离淤泥颗粒进入到滤液中。可以发现,通过离子交换作用,CPAM将淤泥颗粒上的非专性吸附Cd和部分专性吸附Cd解吸到弱双电层水中,泥浆经真空抽滤后,Cd解吸率可达60%以上,而不加CPAM的淤泥中Cd经真空抽滤后解吸率不到1%。

The effects and influencing mechanism of CPAM with different ion degrees,molecular weights,and dosages on the adsorption and desorption characteristics of Cd in dredged sludge were investigated.Results showed that when the initial concentration of Cd in dredged sludge is 0.5μg/L,the Cd concentration in the supernatant fluid is less than 0.1μg/L under the natural sedimentation after the adding of CPAM,which is similar to that without the adding of CPAM.However,under the condition of vacuum filtration,the concentration of Cd in the filtrate can reach 0.35μg/L,and about 64% of soluble Cd desorbs from the sludge particles into the filtrate.The introduction of CPAM can desorb the nonspecific adsorption Cd and some specific adsorption Cd in the sludge particles into the weak double electric water through the ion exchange.After the vacuum filtration,the desorption rate of Cd cand reach more than 60%,instead of 1% without the adding of CPAM.