State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, PR China.
Water Res. 2010 Jan;44(1):59-68. doi: 10.1016/j.watres.2009.08.053. Epub 2009 Sep 8.
Chemical cleaning of fouled hollow-fiber polyvinyl chloride (PVC) membrane with the consecutive use of NaOH and ethanol during ultrafiltration of river water was investigated in the study. Results showed that through the chemical cleaning with 1% NaOH for 30min, a negative cleaning efficiency of -14.6% was observed for the PVC membrane. This might be due to the increase of membrane hydrophobicity, which was reflected by the increase of contact angle from 69.7 degrees to 87.6 degrees . On the other hand, the cleaning efficiency of 85.1% was obtained by the consecutive cleaning with 30min of 1% NaOH and 30min of ethanol. Individual ethanol cleaning could remove 48.5% of the irreversible resistance, indicating that NaOH cleaning also made its contribution (36.6%) to the removal of membrane foulants. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) analyses demonstrated that both NaOH and ethanol were not only able to eliminate the foulants on membrane surface, but also able to remove the in-pore fouling of the PVC membrane. The synergetic effects for removing membrane foulants were observed between the NaOH and ethanol. Furthermore, ethanol could also restore the hydrophilicity of the membrane by decreasing the contact angle from 87.6 degrees to 71.4 degrees . Considering that ethanol is easy to be used and reclaimed, the consecutive chemical cleaning by alkali and ethanol is recommended for PVC membrane in filtration of surface water.
在河水超滤过程中，研究了连续使用 NaOH 和乙醇对污染的中空纤维聚氯乙烯（PVC）膜进行化学清洗。结果表明，通过用 1% NaOH 清洗 30min，PVC 膜的清洗效率为负 14.6%。这可能是由于膜疏水性增加所致，这反映在接触角从 69.7 度增加到 87.6 度。另一方面，通过连续用 1% NaOH 清洗 30min 和乙醇清洗 30min，可获得 85.1%的清洗效率。单独使用乙醇清洗可去除 48.5%的不可逆阻力，表明 NaOH 清洗也对去除膜污染物做出了贡献（36.6%）。扫描电子显微镜（SEM）和原子力显微镜（AFM）分析表明，NaOH 和乙醇不仅能够消除膜表面的污染物，而且能够去除 PVC 膜的孔内污染。NaOH 和乙醇之间观察到去除膜污染物的协同作用。此外，乙醇还可以通过将接触角从 87.6 度降低到 71.4 度来恢复膜的亲水性。考虑到乙醇易于使用和回收，建议在地表水过滤中对 PVC 膜进行碱和乙醇的连续化学清洗。
