Revalorization of Cotton and Cotton/Elastane Knitted Fabric Waste

The present paper demonstrates a simple way for revalorization of differently softened cotton and cotton/elastane knitted fabric waste collected from the textile industry. Such waste was used as an adsorbent for Congo Red (CR) dye, whereby up to 96% removal efficiency was reached. The CR adsorption process onto cationic and silicone softened fabrics is in conformity with Langmuir (with maximum adsorption capacity of 12.533 mg/g) and Freundlich isotherms, respectively. Different adsorption of CR onto cationic and silicone softened fabrics is ascribed to the different softeners’ fixation to them, while the adsorption of CR operates in the same manner, via hydrophobic interactions. The adsorption kinetic data follow the pseudo-second-order model, while the equilibrium was reached after 90 min. Additionally, this study proposed a new circular economy solution for the disposal of fabric waste with adsorbed CR generating additional revenues. The volume electrical resistivity measurements confirmed that the knitted fabric wastes with adsorbed CR have 169–737 times lower resistivities (0.008–0.037 GΩ·cm) than before the adsorption. The inversely proportional correlation between fabrics’ adsorption efficiencies and their volume electrical resistivities after CR adsorption was found. Such knitted fabric waste with adsorbed CR could be defined as dissipative materials and could be used for providing antistatic protection.