The influence of ionic strength and organic compounds on nanoparticle TiO2 (n-TiO2) aggregation

Jaewoong Lee, Shannon L. Bartelt-Hunt, Yusong Li, Erica Jeanne Gilrein

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


This study investigated the aggregation of n-TiO2 in the presence of humic acid (HA) and/or 17β-estradiol (E2) under high ionic strength conditions simulating levels detected in landfill leachate. Aggregation of n-TiO2 was strongly influenced by ionic strength as well as ionic valence in that divalent cations (Ca2+) were more effective than monovalent (Na+) at the surface modification. HA or E2 enhanced aggregation of n-TiO2 in 20 mM CaCl2, however little aggregation was observed in 100 mM NaCl. Similarly, we observed only the increased aggregation of n-TiO2 in the presence of HA/E2. These results showed the critical role of particles' surface charges on the aggregation behaviors of n-TiO2 that HA plays more significantly than E2. However, the slightly increased zeta potential and aggregation of n-TiO2 in the combination of HA and E2 at both 20 mM CaCl2 and 100 mM NaCl means that E2 has influenced on the surface modification of n-TiO2 by adsorption. Based on the aggregation of n-TiO2 under high ionic strength with HA and/or E2, we simulated the mobility of aggregated n-TiO2 in porous media. As a result, we observed that the mobility distance of aggregated n-TiO2 was dramatically influenced by the surface modification with both HA and/or E2 between particles and media. Furthermore, larger mobility distance was observed with larger aggregation of n-TiO2 particles that can be explained by clean bed filtration (CFT) theory.

Original languageEnglish (US)
Pages (from-to)187-193
Number of pages7
StatePublished - Jul 1 2016


  • Aggregation
  • E2
  • HA
  • IS
  • Mobility
  • N-TiO

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

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