A hybrid yellow nanopigment as an environmentally sound alternative to lead chromate pigment for pavement markings

Abstract

This study entails the synthesis of a series of yellow hybrid dye-clay nanopigments (DCNPs) using different yellow cationic dyes, natural, and organomodified montmorillonite. The cationic exchange reaction served as a facile, one-pot, and low-temperature transformation strategy. DCNPs are explored as a type of lead-free eco-friendly pigment to substitute for conventional lead chromate pigment (PbCrO4) for pavement markings. The plate-like DCNP stacks with an approximate hydrodynamic diameter of 2.1 μm were well-dispersed in paint film, forming partially intercalated/exfoliated structure. DCNPs exhibited higher thermal stability, weathering stability, and chemical stability than PbCrO4. DCNPs featured the brilliant yellow shade in pavement marking paint, with the blue-yellow component value (b*) up to 69.9 units. The American pavement marking reference colors can be achieved with a considerably smaller amount of colorant when using DCNP, owing to its exceptional color strength. The cytotoxicity analysis revealed 91%, 66%, and 2% viability of fibroblast cells after a 48h treatment with 0.25 mg/ml natural DCNP, organoclay-based DCNP, and PbCrO4, respectively. In conclusion, the remarkable functional properties and low acute toxicity of the resulting nanopigments suggested the potential application of DCNP as a promising alternative to lead-based pigments in pavement markings.