Attack of Glass by Chelating Agents

The chemical attack of a soda-lime glass by the combined action of ethylene diamine tetraacetic acid and ortho-dihydroxy benzene (catechol) in dilute aqueous solution is reported u a function of pH. A pronounced maximum occurs in the rate of attack at a pH value determined by the anionic species present. The effects are ascribed to the chelation of the protective cations A1³⁺, Ca²⁺, and Mg²⁺ by ethylene diamine tetraacetic acid and to the chelation of Si⁴⁺ by catechol.