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A systematic electrochemical study was performed to understand the influence of HEPES buffer concentration on the degradation behaviour of pure magnesium in Earle’s balanced salt solution (EBSS). Electrochemical impedance spectroscopy and potentiodynamic polarisation experiments suggest that HEPES accelerates the degradation of magnesium. While 5% CO2 in EBSS reduced the polarisation resistance of magnesium by ~79%, addition of HEPES (25 mM) to EBSS decreased the Rp of magnesium by ~98% and escalated the corrosion current by over an order of magnitude as compared to that in EBSS. Increase in HEPES concentration (50 and 100 mM) further increased the degradation of magnesium. Interestingly, the bulk pH difference between EBSS + HEPES and EBSS + CO2, before and after the electrochemical testing, was only marginal. However, the polarisation curves and FTIR spectroscopy analysis suggest that HEPES affected the formation of insoluble salt layer (phosphate and carbonate) on the surface of magnesium. This effect can be attributed to the increase in the ionic strength of the solution due to HEPES addition.

Rights:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: Magnesium, Biomaterials, Degradation, HEPES, EBSS

Date published: 2017-05-16

Publisher: Elsevier BV

Journal:

• Materials Chemistry and Physics (ISSN: 02540584) vol. 197 p. 47-56

Funding:

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5770

First published URL: https://doi.org/10.1016/j.matchemphys.2017.05.024

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Updated at: 2025-09-18 12:30:27 +0900

Published on MDR: 2025-09-18 12:23:04 +0900