聚季铵盐强化超滤处理铬(Ⅵ)

Removal of Chromium(Ⅵ) from Aqueous Solution by Polyelectrolyte Enhanced Ultrafiltration

以聚季铵盐-22(PQ22)为络合剂,研究Cr(Ⅵ)的强化超滤行为,考察聚电解质/金属质量比、pH值及外加盐对PQ22-Cr(Ⅵ)络合体系截留系数和膜通量的影响,并研究了络合体系的浓缩、解络合和洗涤过程.结果表明,当聚电解质/金属质量比为80及pH=9时,Cr(Ⅵ)截留系数大于0.9;外加Cl-,NO3-和SO42-使Cr(Ⅵ)截留系数降低,且SO42-比NO3-和Cl-的影响更大;控制聚电解质/金属质量比为80及pH=9,当浓缩因子为20时,Cr(Ⅵ)浓度从初始的5 mg/L浓缩至82.6 mg/L;对浓缩液解络合,控制Cl-浓度为0.15 mol/L,解络合率为71.1%,以Cl-溶液对解络合液进行洗涤,Cr(Ⅵ)洗脱率可达95.9%.聚季铵盐-22可循环使用.

Polyelectrolyte-enhanced ultrafiltration process for separation of Cr（VI） from aqueous solution was investigated by using polyquaternium-22 （PQ22） as a complexing agent. The effects of polyelectrolyte/metal mass ratio, pH value and additional anions on the Cr（VI） rejection coefficient and membrane flux were examined, and the concentration, decomplexation and washing also studied. The results showed that the rejection coefficient （R） was over 0.9 at the polyelectrolyte/metal mass ratio of 80 and pH=9. R was significantly reduced by adding Cl^-, NO3^- and SO4^2-, and the influential degree of the bivalent anion was far greater than monovalent anions. At the polyelectrolyte/metal mass ratio of 80 and pH=9, Cr（VI） concentration in the concentration process was increased from 5 to 82.6 mg/L when volume concentration factor reached 20. The final concentrated solution was used to study the behavior of decomplexation at KCl concentration of 0.15 mol/L, and the decomplexation rate was 71.1%. When the decomplexation solution was washed with the KCl solution, the elution rate of Cr（VI） reached 95.9%. Polyquaternium-22 could be regenerated.