Low-Toxicity Copper Corrosion Inhibitors

The efficiency of various imidazole derivatives as corrosion inhibitors for copper in hydrochloric and sulfuric acids (HCl and H₂SO₄) was investigated. Electrochemical measurements showed the organic compounds investigated have fairly good inhibiting properties, except for 4-methyl-5-imidazolecarbaldehyde in HCl. Protecting properties of most imidazole derivatives were close to those of commercial inhibitors for copper. Evaluation of the toxicity of the water solutions on the biological system for treatment of waste water — as measured in regard to chemical oxygen demands (COD), aerobic, and anaerobic toxicity — showed the tested inhibitors have relatively low toxicity.