pH值对电渗析法回收厨房垃圾发酵液中乳酸的影响

随着人们环保意识的加强，乳酸作为生物可降解塑料的原料日益受到重视．目前，国内外一些专家都在积极开发廉价乳酸的分离新工艺，如萃取、电渗析、反渗透．电渗析法作为一种新的膜分离技术过去主要运用在苦咸水及海水的淡化上，现在欧美、日本等一些发达国家已运用电渗析法来分离、浓缩回收化工产品．

Effects of pH on recovery of lactic acid from kitchen garbage fermentation broth by electrodialysis

Recovery of lactic acid from kitchen garbage fermentation broth was carried out by electrodialysis (ED). The effects of pH on permeation ratios of lactic acid, ammonia, reducing sugar were discussed. The experimental results showed that pH was the main factor that affected the permeation of ammonia. The rise of pH changed the equilibrium of NH⁺₄, NH3 and NH₃•H₂O, and resulted in the increase of NH₃ and NH₃•H₂O, thus the permeation ratio of ammonia increased. Under the conditions of weak acidity, 12 h ED and 2.0 A•dm^-2 current density, the recovery ratio of lactic acid and the average current efficiency were over 89% and 90%, respectively, whereas the permeation ratios of ammonia and reducing sugar were less than 0.15% and 0.95%, respectively. The product could be used as raw material of polylactic acid synthesis if it was further concentrated by distillation.