Novel synthesis of reactive disperse dyes for dyeing and antibacterial finishing of cotton fabric under scCO2

Synthesis of novel azo pyrazole disperse dyes for dyeing and antibacterial finishing of PET fabric under supercritical carbon dioxide

Supercritical carbon dioxide (scCO2) has been suggested as a good substitution to environmentally harmful water-based tincturing. The present study describes the successful synthesis of some biologically active dispersion tinctures for supercritical carbon dioxide tincturing of polyester fabric. The coupling of 1-cyanoacetylpiperidine (1) with the diazonium salt of aryl amine derivatives (2a-d) produced 1-((aryldiazenyl) cyanoacetyl piperidines (3a-d). To create the derivatives of 4-(phenyldiazenyl)-5-(piperidin-1-yl)-1H-pyrazol-3-amine (5a), the propane nitriles (3a-d) were condensed with hydrazine hydrate. However, the unexpected 3-aminopyrazol-5-ol yellow-red dispersion dyes (4a-d) were identified as the reaction results. The MS, IR, and NMR spectra were used to describe the novel dyes, and the results exactly matched the suggested structures. The antibacterial test, which was conducted using the AATCC method, revealed that some of the compounds (3a-d) and (4a-d) had impressive antibacterial capabilities against the researched +ve and gram -ve bacteria. For eight dyestuffs, the dyeability, color strength, and color fastness of the tincturing process were evaluated. The evaluation focused on determining color uptake using a gauge for color strength (K/S). All dyes displayed excellent rubbing, washing, and light fastness (color change and staining grade of 4-5).

An eco-friendly method of extracting alizarin from Rubia tinctorum roots under supercritical carbon dioxide and its application to wool dyeing

Because of its low critical temperature and pressure levels, supercritical carbon dioxide (scCO₂) is the most widely used supercritical fluid in the supercritical fluid extraction (SFE) technique. Alizarin was extracted from madder roots (Rubia tinctorum) using scCO₂ under different conditions of co-solvent ratio (0-50%), temperature (45-95 °C), pressure (150-250 bar), extraction time (15-120 min), and flow rate (5-9 mL/min). Based on alizarin recovery and minimization of environmental risk, the optimum conditions were determined. SFE was optimum at 90% CO₂:10% methanol (Me), 65 °C, 250 bar, 45 min, and 9 mL/min. The alizarin recovery, and its content in R. tinctorum extract (RE) under the optimum conditions were 1.34 g/kg roots, and 6.42%, respectively. Using conventional dyeing methods, wool fabrics were dyed with RE at different concentrations (2-6%). Various types of mordants were also used in the dyeing process, including chemical and bio-mordants. Color and fastness properties of dyed wool fabrics were evaluated based on RE concentration and mordant type. A higher RE concentration and the use of mordants, specifically Punica granatum (P. granatum) peels, increased the color characteristics. RE and dyed fabrics exhibited good antibacterial activity against the tested bacterial strains, especially Pseudomonas aeruginosa and Escherichia coli.

Optimization of Extraction of Natural Antimicrobial Pigments Using Supercritical Fluids: A Review

It has become increasingly popular to replace chemically synthesized compounds with natural counterparts mostly found in natural sources, such as natural pigments. The conventional extraction processes for these compounds are limited by the toxicity and flammability of the solvents. To obtain pure extracts, it is always a longer process that requires several steps. Supercritical fluid extraction (SFE) is a cutting-edge green technology that is continuously increasing and expanding its fields of application, with benefits such as no waste produced, shorter extraction time, automation, and lower solvent consumption. The SFE of natural pigments has high potential in food, textiles, cosmetics, and pharmaceuticals; there are a number of other applications that can benefit from the SFE technique of natural pigments. The pigments that are extracted via SFE have a high potential for application and sustainability because of their biological and antimicrobial properties as well as low environmental risk. This review provides an update on the SFE technique, specifically as it pertains to the optimization of health-promoting pigments. This review focuses on antimicrobial pigments and the high efficiency of SFE in extracting pure antimicrobial pigments. In addition, the optimal conditions, biological activities, and possible applications of each category are explained.