摘要
Removal of Co(Ⅱ) from aqueous solutions by complexation-ultrafiltration was investigated using polyacrylic acid sodium(PAAS) as complexing agent with the help of rotating disk membrane,and the shear ability of PAA-Co complex was studied. The effects of the mass ratio of PAAS to Co(Ⅱ)(P/M) and pH on the rejection of Co(Ⅱ) were studied,and the optimum conditions were P/M=8 and pH=7. The rejection of Co(Ⅱ) was over 97% when the rotating speed of the disk(n)was less than 710 r/min at the optimum P/M and pH. The distribution of the forms of cobalt on the membrane surface was established by the membrane partition model, and the critical shear rate,the smallest shear rate at which the PAA-Co complex begins to dissociate,was calculated to be1.4×10^4 s^-1,and the corresponding rotating speed was 710 r/min.The PAA-Co complex dissociated when the shear rate was greater than the critical one. The regeneration of PAAS and recovery of Co(Ⅱ) were achieved by shear-induced dissociation and ultrafiltration.
采用聚丙烯酸钠(PAAS)作络合剂,研究旋转盘膜络合-超滤处理含钴稀溶液及PAA-Co络合物的剪切稳定性。研究聚合物/金属离子质量比(P/M)及pH对钴截留率的影响,并得到较佳的P/M及pH条件为P/M=8和pH=7。在此条件下,当旋转盘转速小于710r/min时,PAA-Co络合物的截留率达97%以上。采用络合-解离分区模型研究钴在膜面的存在形态,并得到PAA-Co络合物解络的临界剪切速率(PAA-Co络合物解络的最小剪切速率)。在pH=7条件下,PAA-Co络合物的临界剪切速率为1.4×10^4 s^-1,对应的旋转盘临界转速为710 r/min。当剪切速率大于1.4×10^4s^-1时,PAA-Co络合物解络,可通过剪切诱导解络-超滤实现络合剂和Co(Ⅱ)的分别回收。
基金
Project(24176265)supported by the National Natural Science Foundation of China
