Importance of Protocol Design for Suitable Green In Situ Synthesis of ZnO on Cotton Using Aqueous Extract of Japanese Knotweed Leaves as Reducing Agent

Abstract

This work presents two protocols for the green in situ synthesis of zinc oxide nanoparticles (ZnO-NP) on cotton with the aim to develop sustainable cotton fabric with an ultraviolet protection factor (UPF). The protocols differed in the order of immersing cotton fabric in reactive solutions of three batches, i.e., precursor (0.1 M zinc acetate dihydrate), reducing agent (aqueous extract of Japanese knotweed leaves) and alkali (wood ash waste). The scanning electron microscope (SEM) results showed that ZnO-NP were successfully synthesised on cotton using both protocols; however, only the protocol where cotton was first immersed in alkali, then in the precursor and, lastly, in the reducing agent enabled very high UPF and higher amount of Zn present on the sample. Due to the different order of cotton fabric immersion in the reactive solutions, dissimilar morphology of the ZnO particles was observed, which resulted in different UV blocking abilities of the samples. The antioxidant analysis (DPPH) showed that the natural reducing agent prepared from Japanese knotweed leaves has very high antioxidant activity, which is attributed to phenolic compounds present in the plant. The reflectance spectroscopy results confirmed that the colour yield and colour of the samples did not influence the UPF value. This protocol is an example of green circular economy where waste materials of invasive alien plant species and pellet heating was used as a natural source of phytochemicals, for the direct synthesis of ZnO-NP to develop cotton fabric with UV-protective properties.

Eco-Friendly In Situ ZnO Synthesis on PET Fabric Using Oxygen Plasma and Plant Waste

“…Moreover, it was discovered that the sequence of synthesis solutions is crucial to obtain small and uniformly distributed ZnO particles [7]. Based on the obtained results, this study presents the implementation of the suitable in situ ZnO synthesis protocol described in Verbič et al 2022 [7] on a new textile substrate. The synthesis was performed by immersing samples in three synthesis solutions: natural alkaline medium, zinc precursor and natural reducing agent.…”

“…However, it was soon realised that fully green syntheses performed directly on a textile substrate are not easily achievable, and the use of classical reducing agents and solvents was often further pursued in addition to the natural extract. There are only a few published studies in which green in situ synthesis was performed directly (in situ) on a textile substrate using only natural aqueous extracts [6][7][8], without any chemicals acting as an alkaline medium or reducing agent. However, those syntheses were performed on cotton fabrics.…”

“…However, those syntheses were performed on cotton fabrics. Generally, the authors concluded that for the green synthesis of ZnO on cotton, two criteria must be met, i.e., the alkaline conditions [9,10] and the presence of phenolic compounds in the natural extract is necessary for the synthesis to take place [6,7]. Moreover, it was discovered that the sequence of synthesis solutions is crucial to obtain small and uniformly distributed ZnO particles [7].…”

“…Generally, the authors concluded that for the green synthesis of ZnO on cotton, two criteria must be met, i.e., the alkaline conditions [9,10] and the presence of phenolic compounds in the natural extract is necessary for the synthesis to take place [6,7]. Moreover, it was discovered that the sequence of synthesis solutions is crucial to obtain small and uniformly distributed ZnO particles [7]. Based on the obtained results, this study presents the implementation of the suitable in situ ZnO synthesis protocol described in Verbič et al 2022 [7] on a new textile substrate.…”

Plasma-Assisted Green Synthesis of ZnO Directly on Polyethylene Terephthalate Fabric

“…In some cases, both classical and plant-derived reducing agents have been used for the in situ synthesis of nanoparticles on textiles [14,15]. Moreover, it was shown that classical reducing agents are not necessary when synthesis methods with the proper design are used [16,17]. Pomegranate peels were found to be a great reducing agent for the synthesis of various nanoparticles [18][19][20].…”