利用多效膜蒸馏技术浓缩硫酸和磷酸水溶液

Concentrating Aqueous Solution of Sulfuric Acid and Phosphoric Acid by Multiple-Effect Membrane Distillation

利用自制中空纤维气隙式多效膜蒸馏组件进行了多效膜蒸馏过程浓缩稀硫酸和磷酸溶液的研究,考察了膜入口温度、料液进口浓度和料液流量对渗透通量和造水比的影响。结果表明,膜入口温度升高时渗透通量和造水比增加;料液流量增加,渗透通量增加,而造水比随之降低;料液酸浓度增加,渗透通量和造水比均随之下降,且硫酸的影响更为显著。实验过程中渗透通量和造水比最高可达5.3 L/(m2.h)和11.5。在适当的操作条件下,该过程可将质量分数(下同)为2%的稀硫酸或稀磷酸溶液浓缩至40%以上,且渗透液最大的电导率仍小于200μS/cm。以10%的硫酸溶液为料液,利用2个不同的膜组件进行了持续30 d的多效膜蒸馏过程稳定性实验研究,实验期间所用膜组件操作性能没有明显下降,没有观察到膜渗漏现象。

Multiple-effect membrane distillation（MEMD） was used to concentrate dilute aqueous solution of sulfuric acid or phosphoric acid by using self-made membrane module containing both micropous hydrophobic hollow fibers and dense-wall hollow fibers.Effects of heated feed-in temperature,feed-in flow rate and feed-in concentration on the MEMD performance were experimentally investigated.The experimental results demonstrated that permeation flux and performance ratio increased with the increase of heated feed-in temperature;permeation flux increased with the increase of feed-in flow rate,while performance ratio decreased at the same time;permeation flux and performance ratio decreased with the increase of feed-in concentration.Compared with phosphoric acid,the effects of the concentration of sulfuric acid on the performance of MEMD process were more evident.The maximum permeation flux and performance ratio were 5.3 L/（m2·h） and 11.5,respectively.Aqueous solution of sulfuric acid or phosphoric acid of 2 wt% could be concentrated to 40 wt% or above,while the electrical conductivity of the permeate was still less than 200 μS/cm.By using two AGMD modules,a long-term operational stability of the MEMD process was investigated using aqueous solution of 10% sulfuric acid solution as feed.The MEMD process showed excellent operation stability in a long-term test lasting for 30 days.