Development of betalain-finished plasma-treated nonwoven cotton textiles from beetroot (Beta vulgaris L.) and recycled fabrics for identification of ammonia

Cotton fibers are a primary resource for several textile and non-textile applications. They are characterized by high breathability, softness, and high hydrophilicity. Cotton fibers are used in several sectors, including medicine, automotive, and furniture industries. However, there is a growing desire to identify alternative resources for the production of cotton with low cost and high quality for advanced uses, such as colorimetric detectors. On the other hand, ammonia has shown severe toxicity to human organs and may even cause death. Herein, this study presents an innovative method for plasma-supported coloration of nonwoven fabrics with a betalain natural dye (BND) derived from beetroot (Beta vulgaris L.) for onsite detection of ammonia. High-performance liquid chromatography (HPLC) was employed to analyze an extracted solution of betalain. A mordant was applied to attach betalain to cotton fibers, resulting in a BND/Alum complex of nanoparticles with diameters ranging from 10 to 40 nm according to transmission electron microscopic (TEM) analysis. A thin film of a betalain probe was deposited on plasma-treated fabrics. The colorimetric coordinates, colorimetric strength (K/S), and absorbance spectra indicated that betalain-treated fabric exhibited a detection limit of 0.5–280 ppm for aqueous ammonia, accompanied by a color transition from red (590 nm) to yellow (415 nm) resulting from intramolecular charge delocalization. An isosbestic point was monitored at 484 nm, proving the presence of two isomeric forms of betalain. The betalain-dyed nonwoven cotton fibers indicated adequate colorfastness, ultraviolet shielding, and antibacterial efficiency.