Comment to the paper: Identification of indigoid compounds present in archaeological Maya blue by pyrolysis-silylation-gas chromatography–mass spectrometry (M.T. Doménech-Carbó, L. Osete-Cortina, A. Doménech-Carbó, M.L. Vázquez de Agredos-Pascual and C. Vidal-Lorenzo, J. Anal. Appl. Pyrol. 105 (2014) 355–362)

New Hints on the Maya Blue Formation Process by PCA‐Assisted In Situ XRPD/PDF and Optical Spectroscopy

“…Multivariate analysiso fX RPD in situ data highlights that the MB-formation reactions tarts in most of the samples at 100-120 8Ca nd reaches the maximum rate at 150 8C, but shows differentk inetics dependingo nm ixture composition. For example, hosts with acids ites are not suited to form MB-like nanocomposites, whereas an excesso fd ye (4 wt.% of indigo) causesd ifferent diffusionb ehaviors and thus al ess efficient dye sequestration.M oreover the presence of leachable indigo confirms the limit of 2-3 %i ndigo that can be strongly bound within palygorskite, as discussed by both Domenech-Carbò et al and Ts iantos et al [35][36][37] When comparing the fresh 2wt.% indigo/palygorskite mixture with the same mixture pre-treated at 150 or 175 8C, the samples treated at highert emperatures are clearly and largely different. Hence,t he first process at about 100-120 8Ci sr elated to water elimination (TGA and in situ XRPD data), thus increasing the extent of sites that allow insertiono fi ndigo in the hostings tructure, with environment changes (in situ FORSd ata).…”

“…Moreover the presence of leachable indigo confirms the limit of 2–3 % indigo that can be strongly bound within palygorskite, as discussed by both Domenech‐Carbò et al. and Tsiantos et al . When comparing the fresh 2 wt.% indigo/palygorskite mixture with the same mixture pre‐treated at 150 or 175 °C, the samples treated at higher temperatures are clearly and largely different.…”