*2.2. Dyeing Apparatus*

Dyeing was carried out using an Infra Color Dyeing Machine, which consists of 12 beakers that are mounted in a rotating beaker-carrying wheel. Heating occurs through infrared radiation, cooling through air and automation through the microprocessor programmer DC4 F/R. The maximum temperature was up to 140 ◦C, a maximum heating rate was up to 5 ◦C/min and cooling had a maximum rate up to 3 ◦C/min.

#### *2.3. Methods*

#### 2.3.1. Green Synthesis of Se-NPs

Se-NPs were prepared according to the method reported by Abou Elmaaty et al. [55] through a redox reaction. Sodium hydrogen selenite at different concentrations of 25 mM, 50 mM, 75 mM and 100 mM was added to vitamin C at the same concentration and the volume ratio of 1:1 under magnetic stirring. PVP was used as a stabilizer at the concentration of 0.75–3 g/100mL of vitamin C to enhance the stability of Se-NPs. The change in color from colorless to orange to dark orange indicated the formation of Se-NPs.

#### 2.3.2. Dyeing Procedure of Wool Fabrics with Selenium NPs

Wool fabrics were dyed with different concentrations of Se-NP solution using a wet chemistry method through an immersion process. Briefly, the wool fabrics were immersed into the Se-NP solutions (dyeing solutions) without any chemical additives. Dyeing was performed in a laboratory-scale thermal HT dyeing machine with a liquor-to-goods ratio of 100:1. The solutions containing Se-NPs and wool fabrics were shaken at different temperatures, including room temperature, 40 ◦C, 70 ◦C and 100 ◦C for 60 min to obtain the coloration of fabrics. At the end of the dyeing process, the dyed wool samples were removed, rinsed with water and dried at room temperature.

#### *2.4. Characterization*

TEM images of the synthesized Se-NPs were obtained using a JEM-2100 Transmission Electron Microscope (TEM) with an acceleration voltage of 200 kV to determine the size and morphology of the NPs. Samples for the TEM analysis were prepared by dripping a drop of Se-NP solution onto a carbon-coated copper grid and drying at room temperature.

The surface morphology of wool fabrics, either blank or dyed fabrics, was examined using high resolution scanning electron microscopy (JEOL JSM-6510LB with a field emission gun, Tokyo, Japan). The chemical structure of the dyed samples was analyzed using a surface energy dispersive spectroscopy (EDX) analysis unit (EDAX AMETEK analyzer, Rigaku, Japan) attached to the electron microscope.

X-ray diffraction was analyzed for both the prepared Se-NPs and Se-dyed wool fabrics using an X-ray diffractometer system (XRD) (Bruker D8 ADVANCE, Karlsruhe, Germany). The Se-NP solution was dried at 130 ◦C until completely dried.

#### *2.5. Functional Properties of Se-Dyed Wool Fabrics*

The functionalities of wool fabrics dyed with Se-NPs were evaluated in terms of the UV protection factor (UPF) and antimicrobial activity.

#### 2.5.1. Antimicrobial Activity

The biological activity of the Se-dyed wool samples was evaluated qualitatively against G+ve bacteria (Staphylococcus aureus and Bacillus cereus), G-ve bacteria (Escherichia coli) and yeast (Candida utilis). The antimicrobial test was performed according to the AATCC Test Method (147–1988). The antimicrobial activity was expressed as the growth inhibition zone (mm).

#### 2.5.2. UV-Protection Properties

The ultraviolet protection factor expressed as UPF and transmission of ultraviolet (UV) radiation through wool fabrics were evaluated based on the AS/NZS 4399:1996 test method. The UV protection was rated as good, very good or excellent if the UPF values were between 15–24, 25–39 or above 40, respectively.

#### *2.6. Testing*

#### 2.6.1. Color Measurements

The color coordinates of CIE lab (L \*, a \*, b \*, C \*, and h\*) and color strength (K/S) for both blank and Se-dyed wool fabrics were measured in the wavelength range of 360–720 nm using a Konica Minolta spectrophotometer (CM-3600 d, Minolta, Tokyo, Japan). All samples were measured in three different areas, bearing in mind both sides of the fabrics, and the mean values were recorded.

### 2.6.2. Fastness Properties

The color fastness properties were evaluated for all Se-dyed wool fabrics in accordance with the standard test method. Washing, rubbing and light fastness were measured according to the method of AATCC test methods (61–1972), (8–1972) and (16A–1972), respectively.

#### 2.6.3. Durability Test

Durability to washing of the imparted functionalities (antimicrobial activity and UVprotection properties) as well as color strength (K/S) of Se-dyed wool fabrics were evaluated according to AATCC Test Method 61(2A)-1996 after 10 laundering cycles.

#### 2.6.4. Mechanical Properties

The tensile strength (maximum load) and elongation at break (maximum strain) of blank and Se-dyed wool fabrics at high temperature were evaluated using the strip test method on a multi-tester machine according to ASTM-D4850 with a load cell 500 N, preload 0.01 N, speed of 100 mm/min and gauge length of 100 mm.
