Effect of crystallinity and surface silanol groups on rheological properties of different sepiolites

Mustafa Çınar*, Ilhan Gülgönül, Orhan Ozdemir, Mehmet S. Çelik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In this study, differences in the rheological properties of three different types of brown sepiolites (K1, K2, and K3) along with one beige (B) sepiolite with different physicochemical properties were explained based on their crystallinity and level of surface silanol groups. Towards this aim, SEM images, XRD and chemical analyses, cation exchange capacity (CEC), and water absorption tests were conducted along with surface area measurements and time-dependent pH profiles. The pH profiles at 3% by wt. revealed that each sepiolite sample attained the equilibrium at different times. These differences showed a parallel behavior with the degree of crystallinity. While sepiolite with better crystallinity (K1) was rather slow in reaching the equilibrium pH, the sepiolites with poor crystallinity (B and K3) reached their equilibrium pH more quickly. The rheological studies conducted with different sepiolites at 3% solids concentration exhibited time-dependent flow of the Bingham plastic model and thixotropic. Differences observed in the rheological behavior of sepiolites were found to correlate with the fiber size, CEC, surface area, and water absorption. The results further indicated that sepiolites with low crystallinity or high level of surface silanol groups (K3 and B sepiolites) show the best rheological properties.

Original languageEnglish
Article number153947
JournalPhysicochemical Problems of Mineral Processing
Issue number5
Publication statusPublished - 2022

Bibliographical note

Publisher Copyright:
© Wroclaw University of Science and Technology


The authors would like to acknowledge the financial support of TÜBİTAK-The Scientific and Technological Research Council of Turkey (Project Number: 104M179). We also would like to express our endless gratitude to our valuable teacher Prof. Mehmet S. Çelik, who has not spared all kinds of help throughout our academic life and has made great contributions to our scientific development starting from our student life.

FundersFunder number
TÜBİTAK-The Scientific and Technological Research Council of Turkey104M179


    • Crystallinity
    • Ph
    • Rheology
    • Sepiolite


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