Association of indigo with zeolites for improved colour stabilization

TL;DR

This study demonstrates that associating indigo with MFI zeolite significantly enhances its colour stability, offering a promising approach for durable natural pigments and insights into historical pigment stability.

Contribution

The paper introduces a new hybrid pigment of indigo with MFI zeolite, showing improved stability and identifying pore size matching as a key factor.

Findings

Indigo@MFI exhibits the highest stability among tested composites.

Matching pore size with indigo molecule enhances stability.

High colour stability suggests potential for durable natural pigments.

Abstract

The durability of an organic colour and its resistance against external chemical agents and exposure to light can be significantly enhanced by hybridizing the natural dye with a mineral. In search for stable natural pigments, the present work focuses on the association of indigo blue with several zeolitic matrices (LTA zeolite, mordenite, MFI zeolite). The manufacturing of the hybrid pigment is tested under varying oxidising conditions, using Raman and UV-visible spectrometric techniques. Blending indigo with MFI is shown to yield the most stable composite in all of our artificial indigo pigments. In absence of defects and substituted cations such as aluminum in the framework of the MFI zeolite matrix, we show that matching the pore size with the dimensions of the guest indigo molecule is the key factor. The evidence for the high colour stability of indigo@MFI opens a new path for modeling the stability of indigo in various alumino-silicate substrates such as in the historical Maya Blue pigment.