聚丙烯酸钠络合-超滤分离钯(II)

Separation of Pd(II) by Complexation-Ultrafiltration Process with Poly(acrylic acid) Sodium

以聚丙烯酸钠(PAAS)为络合剂,研究钯(II)的络合-超滤行为.考察聚合物/金属质量比(rp/m)、pH、膜两侧压差(Δp)对膜通量(J)和钯截留系数(RPd)的影响,发现J不随rp/m变化,随pH增大而增大,随Δp增大呈线性递增;RPd随rp/m或pH增大而增大,与Δp无关.控制rp/m=2和pH=6,PAAS-钯(II)溶液的浓缩结果表明,随体积浓缩因子增大,J略有下降,RPd接近1,截留液钯浓度(Cr)线性递增,渗透液钯浓度(Cp)约0.07mg/L.以浓缩液为研究对象,在pH=3下考察PAAS-钯(II)的解络合行为,随时间延长,Cr不变,Cp逐渐增至100.9mg/L,解络合平衡时间为13min,解络合率为56.3%.对解络合液洗涤超滤,当洗涤液体积为原料液体积的3.5倍时,Cr从179.3降至5.2mg/L,钯洗脱率为97.1%.

Complexation-ultrafiltration process for separation of palladium（II） from aqueous solution was investigated by using poly（acrylic acid） sodium（PAAS） as a complexing agent. The effects of polymer/metal mass ratio（rp/m） ,pH value and transmembrane pressure（Δp） on permeate flux（J） and palladium rejection coefficient（RPd） were investigated. It was found that J did not change with increasing of rp/m,and increased with pH or Δp. RPd increased with rp/m or pH,but did not vary with Δp. The concentration experiment was carried out at rp/m=2 and pH=6. The results showed that J declined slightly and RPd was about equal to 1 with increasing of volume concentration factor（Fv） . Palladium concentration in the retentate（Cr） increased linearly with Fv,whereas palladium concentration in the permeate（Cp） was always about 0.07 mg/L. The decomplexation experiment was done at pH=3 by using the previous concentrated solution. Cr did not change but Cp increased gradually to 100.9 mg/L with increasing of decomplexation time. It took about 13 min to get the decomplexation equilibrium. The decomplexation rate of palladium（II） -PAAS complexes reached 56.3%. Further,an ultrafiltration experiment was carried out by using the washing water. If the volume of washing water was 3.5 times larger than the feed volume,Cr decreased from 179.3 to 5.2 mg/L,which corresponded to palladium removal rate of 97.1%.