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

Anja Verbič,Katja Brenčič,Gregor Primc,Marija Gorjanc

doi:10.3390/f13020143

Anja Verbič, Katja Brenčič + Show 2 more

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https://doi.org/10.3390/f13020143

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Journal: Forests	Publication Date: Jan 19, 2022
Citations: 8	License type: CC BY 4.0

Affiliation: University of Ljubljana, Jožef Stefan Institute

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.

Highlights

Zinc oxide (ZnO) exhibits exceptional photocatalytic and broad UV range-absorbing properties, stability under UV radiation and increased temperature [1,2], which is why, in the past years, it has been increasingly studied for textile applications
The results showed that the synthesis protocol where the immersion of cotton fabric in wood ash extract was followed by immersion in the zinc precursor and, immersion in the natural extract resulted in uniformly coated fibres with a higher amount of zinc oxide nanoparticles (ZnO-NP), which enabled great protection against UV radiation (UPF = 46.57)
Similar K/S values were obtained, which means that both samples adsorbed similar amounts of the natural extract, which was confirmed with the DPPH assay

Summary

Introduction

Zinc oxide (ZnO) exhibits exceptional photocatalytic and broad UV range-absorbing properties, stability under UV radiation and increased temperature [1,2], which is why, in the past years, it has been increasingly studied for textile applications. While ZnO is typically synthesised chemically and applied on textiles in a separate step (ex situ) [4,6], direct (in situ) synthesis has been widely researched in the past decade. It is a one-step process in which the synthesis and the deposition of nanoparticles on the surface of the substrate is carried out simultaneously [7,8,9]. If the in situ synthesis process is fully performed in the presence of a textile substrate (e.g., cellulose), such process has to be carried out carefully, i.e., the synthesis temperatures cannot exceed

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