Effect of solubility and partition coefficient on the toxicity of corrosion inhibitors used in the oil industry

The present work studied the physicochemical properties, i.e., solubility and partition coefficient and toxicity level of eight corrosion inhibitors (CIs), including two commercial CIs and six synthesized CIs by green chemistry as an ecological alternative to commercial CIs. The six environmentally friendly CIs were synthesized considering the basic principles of green chemistry, under ambient temperature and pressure conditions and in the absence of solvents, with a mass reaction efficiency greater than 80% and without the generation of residues. The chemical structure of the CI, the temperature, and the solvent are factors that determine CI solubility; most CIs exhibit greater solubility in polar media, such as isopropanol: saline solution mixture. The partition coefficient in the aqueous phase: organic phase and mixtures with different volumetric proportions were higher for the environmentally friendly CI in an 80:20 vol% mixture. The partition coefficients of the green inhibitors increased with increasing size of the hydrocarbon chain and with increasing number of zwitterionic groups, obtaining the following order: CI-R18/2 \(>\) $>$ CI-R16/2 \(>\) $>$ CI-R12/2 \(>\) $>$ CI-R18 \(>\) $>$ CI-R16 \(>\) $>$ CI-R12. The 50% effective concentration (EC₅₀), based on stimulation of root growth of Allium cepa, was lowest for CI-IMPG2 and CI-R16-2. The CIs with the lowest % MI were CI-R16/2 and CI-IMPG2, showing less cytotoxic damage, and those with the highest % MI were CI-R12 and CI-PG12A, showing greater cytotoxic damage.