Saponite-anthocyanin pigments: Slipping between the sheets

Abstract

The present work describes the synthesis and characterization of hybrid materials based on β-cyclodextrin (β-CD) and cetyltrimethylammonium bromide (CTAB) intercalated into saponite (SAP) and a commercially available powder of anthocyanin dye, Crystal Red Grape (RG). The interactions between the organic dye guest and the organo-clay host were investigated by X-ray diffraction, thermogravimetric analysis, transmission electronic microscopy and 13 C solid state nuclear magnetic resonance. The results support complex formation between β-CD and CTAB, their intercalation into the clay interlayer spaces or surface loading, and their interaction with RG (CTAB_SAP-RG, β-CD_SAP-RG and β-CD+CTAB_SAP-RG).The hybrid pigments formed exhibit different colors, enhanced stability against visible light irradiation and basic pH conditions. These hybrid pigments are environmentally friendly and can be promising candidates in different application fields.

Nanostructured pH‐Indicator Films Based on Cassava Starch, Laponite, and Jambolan (Syzygium cumini) Fruit Manufactured by Thermo‐Compression

“…[ 2 ] In the current research, a reduction in the alteration of a * values in the films suggests that Lap could protect the anthocyanins in the films against visible light irradiation. Similar results were informed in anthocyanins from acerola juice, [ 15 ] as well as in dry anthocyanins , [ 16–18 ] both stabilized with nanoclays.…”

“…A recent alternative to improve the stability of anthocyanins is through their interaction with nanoclays; this approach has been used to stabilize anthocyanins in acerola juice, [ 15 ] and most recently to manufacture dry powders containing natural pigments (biohybrids) with potential food and pharmacological applications. [ 16–18 ] Laponite (Lap) is a nanoclay used to improve physicochemical properties of food packaging materials based on biopolymer [ 19–23 ] or to manufacture biohybrids containing anthocyanins. [ 17 ] To date, no study has explored the use of nanoclays and particularly the use of Lap to stabilize anthocyanins during the manufacturing process and film application.…”

Uses of Nanoclays and Adsorbents for Dye Recovery: A Textile Industry Review

“…It possesses negatively charged layers that are, in turn, neutralized by other ions with positive Na + Mg 2+ charges. Saponite's cation exchange capacity (CEC) has been quantified as 100 cmol•kg −1 [194][195][196][197][198]. XRD and SEM/EDX characterizations shows the clay mineral has the structural formula INT Na TET [Si 7 Al] OCT [Mg 6 ]O 20 (OH) 4 [199].…”

“…Compared to other nanoclay minerals such as MMT, it can be stated that Sap offers greater thermal stability [201], a smaller particle size (approx. 50 nm) [194][195][196][197][198], and is simpler to delaminate and exfoliate in nanoplate units, or as individual nanolayers in aqueous solution [202]. However, the downside of natural Spa is that it is not abundantly available.…”

Anthocyanin Hybrid Nanopigments from Pomegranate Waste: Colour, Thermomechanical Stability and Environmental Impact of Polyester-Based Bionanocomposites

“…The development of stabilization strategies to improve the colour stability of ACNs such as the addition of co-pigments, formation of supramolecular complexes and encapsulation systems, and protection with natural clay minerals were proposed by Li et al [19]. In this sense, it has been proved that colour stabilization can be achieved by using hybridization of clay nanostructures [20][21][22]. A number of recent studies have focused on the adsorption of ACNs to obtain dye/clay hybrid pigments with improved colour fastness and stability which include reports of stable hybrid pigments prepared from ACNs and several clay minerals that undergo reversible pH-dependent colour changes [23][24][25].…”