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Effect of Organic Additives on Electrochemical Surface Precipitation and Polymorphism of CaCO 3
Author(s) -
Granit N.F.,
Korin E.,
Bettelheim A.
Publication year - 2003
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200390052
Subject(s) - vaterite , calcite , polyacrylic acid , nucleation , chemistry , electrochemistry , precipitation , polymer , adsorption , inorganic chemistry , calcium carbonate , deposition (geology) , chemical engineering , electrode , mineralogy , aragonite , organic chemistry , paleontology , physics , sediment , meteorology , engineering , biology
The inhibition effect of three organic additives on the precipitation and polymorphism of CaCO 3 deposited on gold surfaces was investigated using electrochemical and microscopic techniques. Additives, two polyacrylic acid (PAA) polymers with different molecular weights (Mw 2100, Mw 30,000), and 1,2,4,5‐benzenetetracarboxylic acid (BTCA), were either added to the solution before or during deposition. In the presence of 100 ppm of one of the three additives in solution, almost no scale was observed on the surface for at least 24 hours. In the presence of lower concentrations of PAA Mw 2100, only distorted calcite crystals were obtained while with PAA Mw 30,000 the polymorph was spherical vaterite. A mixture of calcite and vaterite was observed with the BTCA additive. Addition of the polymers inhibits further nucleation and growth even if added after partial deposition of CaCO 3 while BTCA has no effect once nucleation has started. The results indicate that the inhibition effect of the PAA polymers is due to adsorption on the electrode surface while the effect of BTCA is related to chelation of calcium ions in solution.