Effects of humic acid release from sepiolite on the interfacial and rheological properties of alkaline dispersions

Benli B.

APPLIED CLAY SCIENCE, cilt.102, ss.1-7, 2014 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 102
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.clay.2014.10.004
  • Dergi Adı: APPLIED CLAY SCIENCE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.1-7
  • İstanbul Teknik Üniversitesi Adresli: Hayır

Özet

Humic acid (HA) is a major extractable and soluble component of soil organic matter that can play an important role in the stability of environmental colloidal dispersions. This study suggests that HA content of sepiolite is one of the essential reasons for non-Newtonian behaviour of sepiolite dispersions in alkaline media. Releases of HA from sepiolite matrix dramatically changed their rheological properties (thixotropy, apparent viscosity and yield stress), and interestingly, the level of sepiolite surface hydrophobicity. Alkaline environments also increased the release of Mg2+ ions from the sepiolite matrix and, thus, caused to a stable complex formation with HA macromolecules. This colloidal solid phase was directly observed and imaged by atomic force microscopy (AFM) which revealed a spherical shape of complexes between Mg2+ ions and HA in the size range of 18-63 +/- 8 nm at pH 11.5.