膜蒸馏浓缩硫氰酸铵溶液的研究

Study on Concentration of Ammonium Thiocyanate by Membrane Distillation

以PVDF膜为材料,采用减压膜蒸馏对硫氰酸铵溶液进行浓缩,研究各种影响因素对膜通量的影响。结果表明:膜通量随进料液温度和冷侧真空度的增加而显著增加;流速增加,膜通量略有增加;浓度较低时,膜通量随浓度的增加缓慢下降,浓度较高时,膜通量随浓度的增加骤降;高浓度连续运行时,膜通量的衰减随时间的增加而加剧;PVDF膜疏水性较好,截留率保持在99.9%左右。膜丝用去离子水清洗、烘干后,膜通量与初始值相当。

Hydrophobic polyvinylidene fluoride （PVDF） hollow fiber membrane was used in the concentration of ammonium thiocyanate by vacuum membrane （VMD） method. The effect of operation conditions of VMD process on the membrane flux was studied. The results showed that the membrane flux increased with the increase of feeding liquid temperature and vacuum degree in the cold side; With the increase of the velocity, the membrane flux increased; The membrane flux decreased very slowly with the increasing of concentration at low concentration, but sudden drawdown at high concentration. The attenuation of membrane flux intensified with the increasing of the running time during the continuous operation of high concentration. The retention rate kept about 99.9 % showed that the PVDF hollow fiber membrane possessed perfect hydrophobicity. After washing by de-ionized water, the membrane flux is comparable to initial value.