Retention of small charged impurities during ultrafiltration

Jiahui Shao, Andrew L. Zydney

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Ultrafiltration is used to remove small impurities from a variety of processing streams. However, the clearance of small charged impurities may be inadequate due to electrostatic exclusion by the charged ultrafiltration membranes, an effect that has been largely unappreciated. Ultrafiltration experiments were performed to evaluate the transmission of several model impurities with different electrical charge through ultrafiltration membranes having different surface charge characteristics. Highly charged impurities are strongly rejected by charged cellulose and polyethersulfone membranes even though these solutes are much smaller than the membrane pore size. These effects could be eliminated by using high ionic strength solutions to shield the electrostatic interactions. The sieving data are in good agreement with model calculations based on the partitioning of charged spheres into charged cylindrical pores. Guidelines are developed for estimating conditions needed to obtain effective removal of small charged impurities through charged ultrafiltration membranes.

Original languageEnglish (US)
Pages (from-to)7-13
Number of pages7
JournalBiotechnology and bioengineering
Issue number1
StatePublished - Jul 5 2004

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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