Use of pomegranate peels and walnut green husks as the green antimicrobial agents to reduce the consumption of inorganic nanoparticles on wool yarns

Abstract

For reducing the cost of production and saving the environment, the utilization of chemicals, energy, and processing time should be minimized as much as possible. In this study, antimicrobial finishing of wool fibers was achieved by synthesizing Ag/Cu2O/ZnO nanoparticles (NPs) in-situ on the surface of wool fibers, and subsequently dyeing with two natural dyes extracted from Pomegranate peels and Walnut Green husks. The extracted natural dyes had also noticeable antimicrobial activities. This decreased the consumption of Ag/Cu2O/ZnO nanoparticles (NPs) for antimicrobial finishing of wool yarns. The wool samples were dyed at the initial dye concentration of 30% over weight of fiber (o.w.f.), at 100 °C, pH 5.0 for 60 min. The treated samples were characterized by Scanning Electron Microscope (SEM), X-ray diffraction (XRD) analysis, reflectance spectrophotometer, and electromechanical tensile tester. The presence of nanoparticles was confirmed on the surface of the samples by SEM micrographs and XRD profiles. The mechanical properties of the treated samples improved slightly (less than 2%). The antimicrobial activities of the samples treated only with Pomegranate peels and Walnut Green husks were 65% and 35%, respectively. The antimicrobial activity of the treated wool yarns with inorganic salts after the dyeing process was excellent (almost 100%). Moreover, the wash and light fastness properties of the treated samples were all very good to excellent. The dyed sample treated with Ag salt maintained its high antimicrobial activity (>91%) even after 10 repeated washing cycles. The light-fastness of the dyed samples was improved from moderate (5) to very good (7–8) after treatment with the inorganic salts. The proposed eco-friendly dyeing process can also improve the antimicrobial properties of wool yarns.