Dissolution of the barite (001) surface by the chelating agent DTPA as studied with non-contact atomic force microscopy

Kang Shi Wang, Roland Resch, Kai Dunn, Patrick Shuler, Yongchun Tang, Bruce E. Koel, Teh Fu Yen

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


DTPA (diethylenetriaminepentaacetic acid) is a chelating agent widely used for removal of barium sulfate (barite) scale in the petroleum industry. In this paper we report ex-situ investigations of barite dissolution in deionized water and in 0.18 M DTPA aqueous solutions. Non-contact atomic force microscopy (NC-AFM) was used to observe dissolution on the BaSO4 (001) cleavage surface. Dissolution was carried out at room temperature in a 10 ml reactor. Each sample was first etched in solution and dried before examination by NC-AFM. Dissolution on the BaSO4 (001) surface took place via development of etch pits. In deionized water, triangular etch pits were observed on the (001) terraces at room temperature. And, zigzag shaped etch pits were found at the edges of steps. In DTPA solutions, etch pits on the (001) terraces were observed and these became deeper and longer with increasing time. The geometry of these etch pits was trapezoidal, and/or trapezohedral. To explain this characteristic morphology caused by dissolution we suggest that the active sites of one DTPA molecule bind to two or three Ba2+ cations exposed on the (001) surface. Copyright (C) 1999 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)217-227
Number of pages11
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Issue number3
StatePublished - Dec 1999

All Science Journal Classification (ASJC) codes

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry


  • Barite
  • Chelating agent
  • Diethylenetriaiminepentaacetic acid
  • Etch pits
  • Non-contact atomic force microscopy


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