Removal of micropollutants and NOM in carbon nanotube-UF membrane system from seawater

Water Sci Technol. 2011;63(11):2737-44. doi: 10.2166/wst.2011.602.

Abstract

One of the main problems for seawater reverse osmosis desalination is membrane fouling associated with natural organic matter. Bisphenol-A (BPA) and 17alpha-ethinylestradiol (EE2) are well-known endocrine-disrupting compounds that have been detected in wastewater and seawater. In this study, the contribution of carbon nanotubes (CNTs, single-walled carbon nanotubes) to membrane fouling control and the potential adsorption mechanisms of BPA and EE2 were investigated using artificial seawater (ASW) in a bench scale ultrafiltration (UF) membrane coupled with CNTs. For high ionic strength ASW, UVA254 nm is a good alternative for highly aromatic dissolved organic carbon (DOC) determination, with a very strong linear relationship (R2 > or = 0.99) with increasing DOC concentrations. Approximately 80% of DOC in ASW was rejected by the CNT-UF system where 31% of DOC was removed due to adsorption by CNTs. The presence of CNTs shows a 20% increase in membrane flux in ASW. A strong linear correlation between retention and adsorption of BPA and EE2 was obtained. The percentage of adsorption/retention of BPA and EE2 in UF-CNTs follows the order: 94.0/96.6 (DI + CNTs, EE2) > 86.2/90.0 (ASW + CNTs, EE2) > 73.6/78.9 (DI + CNTS, BPA) > or = 74.1/77.3 (ASW + CNTS, BPA) > 29.8/29.8 (ASW, EE2) approximately equal to 27.3/27.3 (ASW, BPA) > or = 25.3/25.3 (DI, EE2) approximately equal to 24.8/24.8 (DI, BPA). This indicates that retention by the UF-CNT system is mainly due to adsorption. Overall, EE2 adsorption was greater than BPA during the UF-CNT experiments, presumably due to the higher hydrophobicity of EE2 than BPA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Benzhydryl Compounds
  • Ethinyl Estradiol / chemistry
  • Membranes, Artificial*
  • Osmosis
  • Phenols / chemistry
  • Seawater / chemistry*
  • Water Pollutants, Chemical / chemistry*
  • Water Purification / instrumentation*
  • Water Purification / methods*

Substances

  • Benzhydryl Compounds
  • Membranes, Artificial
  • Phenols
  • Water Pollutants, Chemical
  • Ethinyl Estradiol
  • bisphenol A