*2.3.2.2. Vat dyeing procedure*

*2.2.3. Dynamometer tensile testing*

10 Eco-Friendly Textile Dyeing and Finishing

*2.3.1. Nanoparticles*

**2.3. Modification by dyeing and nanoparticles**

kept under an argon atmosphere for another hour [71].

*2.3.2. Dyeing of cotton samples*

*2.3.2.1. Dyeing with reactive dyes.*

1 g/l of CIBAPON R was used.

Breaking strength and elongation of untreated and plasma-treated fabrics were analyzed ac‐ cording to the ISO 2062:1997 standard. Instron 6022 was used for this purpose. 100 mm sam‐ ples of cotton yarn were analyzed using a pre-loading of 0.5 cN/tex and a speed of 250 mm/ min. Samples were conditioned according to the ISO 139 standard. Tensile stress (cN/dtex) and elongation ε (%) are the mean values of the measured tensile strength and the elonga‐

For a research three different types of silver nanoparticles were used: silver nanoparticles of known dimensions (Ames Goldsmith Inc.), commercial form RucoBac AGP (Rudolph Chemie) and laboratory synthesized colloidal silver nanoparticles. Silver nanoparticles of known dimensions was medium density mono-dispersed 30 nm silver powder (Silver Nano Powder NP-30) and high density mono-dispersed 80 nm silver powder (Silver Nano Powder NP-80) [68]. The powdered silver nanoparticles are namely intended for a fine line printing (Ink-jet printing) and for electronics use. Because of their purity and known size they are very suitable and important for studies of adhesion to textile materials [69]. The initial con‐ centration of silver powders in the dyeing baths was 20 mg/l. Commercial form of silver nanoparticles RucoBac AGP is a hygienic finish for all fiber types. It is a highly concentrated hygiene and freshness system complying with the Oeko-Tex® standard 100. RucoBac AGP is a nano-dispersion of titanium dioxide (TiO2) as the carrier of the active component silver chloride (AgCl) [70]. The recommended concentration of RucoBac AGP is 0.2–0.5%. Labora‐ tory synthesized colloidal silver nanoparticles were made by a reduction of silver salt in an aqueous solution at room temperature. An amount of 25.5 mg of AgNO3 was dissolved in 750 ml of bi-distilled water, and argon gas was introduced into the solution for 30 min. The reduction was performed with 375 mg of NaBH4 under constant stirring. The solution was

Exhaust dyeing with or without the addition of silver nanoparticles [3, 27, 72] was per‐ formed on untreated and plasma-treated cotton samples. The dye solutions were separate‐ ly prepared using two different dyeing concentrations: blank (dyeing without dyestuff) and 0.05% on weight of fabric (owf) of Cibacron Deep Red S-B in liquor ratio 20 : 1. Dye‐ ing baths contained 30 g/l of salt (Na2SO4 anhydrous) and 8 g/l of sodium carbonate (Na2CO3 anhydrous). After the dyeing process, rinsing with distilled water was per‐ formed and neutralization with 1 ml/l of 30% acetic acid (CH3COOH). As a soaping agent

tion of 10 specimens, respectively, in the warp and in the weft directions.

Vat dyeing was performed on untreated and plasma-treated cotton samples. The dyed cot‐ ton fabrics were post-treated in a colloidal silver solution [71]. A dyeing bath was prepared with 4% owf Bezathren Blau BCE, 15 ml/l NaOH 38°Bé and 3.5 g/l Na2S2O4. The liquor ratio was 83.3 : 1. The dyeing of cotton fabrics was performed at 60°C for 60 min. The dyed sam‐ ples were rinsed twice in deionised water for 5 min, post-treated in 2 ml/l HCOOH 85% for 5 min and rinsed in deionised water for 5 min.

#### **2.4. Color measurements**

Color measurements of differently modified samples were performed after conditioning them according to the ISO 139 standard. CIE standard illuminant D65/10 was used on a Da‐ tacolor Spectraflash SF 600-CT reflection spectrophotometer. The aperture diameter of the measuring port of the spectrophotometer was 9 mm.

## **2.5. Elemental and antimicrobial analysis**

The quantity of adsorbed silver was determined using ICP-MS. This technique combines a high-temperature inductively coupled plasma (ICP) source with a mass spectrometer (MS). The antibacterial efficiency of functionalized textiles was determined using microbiological tests according to the ASTM Designation: E 2149–01 method. Antibacterial activity of the cotton fabrics was tested by a certified laboratory against *Staphylococcus aureus* (ATCC 25923), *Escherichia coli* (ATCC 25922), *Streptococcus faecalis* (ATCC 27853) and *Pseudomonas aeruginosa* (ATCC 27853).
