膜蒸馏去除水中Cr(Ⅵ)研究

RREMOVAL OF Cr(Ⅵ) BY MEMBRANE DISTILLATION

构建PVDF中空纤维疏水膜为膜组件的膜蒸馏装置对100 mg/L的实验室Cr(VI)废水进行处理。研究了不同温差条件下膜通量变化情况、膜通量及产水电导率随时间变化情况、进出水Cr(VI)浓度变化情况及长周期运行条件下的膜通量变化情况。实验结果表明:随着温差的增大,膜通量保持增长趋势,当冷热侧温差达35℃以上时,膜通量增长速率放缓,兼顾经济与效率计,冷热侧温差以35℃为宜;在实验周期内,膜通量在8.21~8.36 kg/(m2·h)变化,电导率维持在3.8~3.9μS/cm;产水的六价铬浓度12 h之内稳定在0.026~0.03 mg/L,随着膜蒸馏实验的进行,产水浓度开始增大,但均在0.5 mg/L排放标准以下;168 h的长周期实验过程膜通量维持在8.1~8.35 kg/(m2·h),产水电导率维持在3.7~4.3μS/cm,说明以PVDF中空纤维疏水膜为核心的膜蒸馏技术对Cr(VI)具有稳定的去除效果。

Membrane distillation device with PVDF as the core was introduced to treat laboratory wastewater contained100 mg / L Cr( Ⅵ). Effects of temperature difference between hot-side and cool-side on flux,variation of permeate flux and conductivity as a function of run time,concentration of feed Cr( Ⅵ) and permeate Cr( Ⅵ) and variation of permeate flux and conductivity during long-term MD performance were investigated. The result shows that the temperature difference between hotside and cool-side is 35 ℃. The permeate flux verified from 8. 21 to 8. 36 kg /( m2·h) and the conductivity maintained at3. 8 ~ 3. 9 μS / cm in the whole process. The concentration of permeate Cr( Ⅵ) stabilized at 0. 026 ~ 0. 03 mg / L during 12 h performance and increased as the experiment going,both of which remained below 0. 5 mg / L. The permeate flux stabilized at8. 1 ~ 8. 35 kg /( m2·h) during 168 h long term experiment performance and the conductivity stabilized at 3. 7 ~ 4. 3 μS/cm,which shows that the membrane distillation has stable removal efficiency for Cr( Ⅵ).