Ca2+-exchange in layered zirconium orthophosphate, α-ZrP: Chemical study and potential application for zinc corrosion inhibition
Abstract
The control of the corrosion phenomenon occurring at the metal interface requires the development of new non-toxic anticorrosion additives. For this purpose, zirconium orthophosphate compounds (Zr(HPO4)2,H2O noted α-ZrP) were synthesized by both hydrothermal and refluxing methods The Ca2+-cationic exchange in the layered structure is kinetically favoured by low crystallinity of α-ZrP synthesized by refluxing process, and leads to the formation of CaZr(PO4)2,4H2O, noted Ca2+-ZrP. The H+/Ca2+ exchange mechanism is mainly triggered by acid-base considerations, and especially the pKa of α-ZrP/Ca2+-ZrP acid-base couple (evaluated to 2.5). Both compounds are acidic compounds by internal exchangeable H+ for α-ZrP and surface protons for Ca2+-ZrP, and can be used as potential inhibitors of zinc corrosion. Electrochemical measurements show that Ca2+-ZrP compounds dispersed in the NaCl electrolyte buffer the pH value over a long time and therefore allow controlling the corrosion rate of zinc.
- Publication:
-
Applied Surface Science
- Pub Date:
- November 2017
- DOI:
- 10.1016/j.apsusc.2017.06.083
- Bibcode:
- 2017ApSS..422..778B
- Keywords:
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- Ion exchange;
- Zinc corrosion;
- Smart inhibitors;
- Layered compounds