Development of Antibacterial Functionalized Textiles with ZnO

Abstract

With the continuous rise in consumption and contamination of water due to industrial and domestic activities, the development of viable, sustainable, and innovative solutions for water treatment has become increasingly important. At the same time, there has been an increased interest in nanomaterials for applications in various fields. Zinc oxide nanoparticles (ZnO NPs) have become a highly attractive material across various industries due to its wide array of properties which include high chemical and thermal stability, UV protection, thermal conductivity, unique piezoelectric, optical, and luminescent properties, as well as self-cleaning photocatalytic and antibacterial activities. Because of this, the functionalization of textiles with ZnO NPs has viable applications in a variety of fields including water treatment. The project to which the work of this thesis is associated, has the goal of developing a functionalized textile, composed of nylon 6 coated in ZnO NPs, that enables the antibacterial treatment of continuously flowing process water in dark conditions. To that end, the objectives of this thesis are to conduct a series of experiments to determine the conditions at which an optimal ZnO NP coating is achieved on the nylon textile, by employing dip coating, while ensuring that the resulting functionalized textile exhibits antibacterial properties in the dark. Several experiments were conducted, evaluating the effects of operating conditions, ZnO synthesis methods, ZnO NP suspension concentrations and suface activation processes for the nylon: acid activation using HCl and Acetic Acid, basic activation using NaOH and physical activation using UVC irradiation. Characterization techniques, such as XRD, TEM, SEM, EDX and FTIR, were carried out with the aim of confirming the nature of the material of the coating achieved on the nylon and evaluating the effects of the activation processes on the nylon’s molecular structure. The degradation of Nitro Blue Tetrazolium from the contact with the functionalized nylon samples was tested to confirm the presence of the ROS formation mechanism to which the ZnO NP’s antibacterial activity is attributed. It was concluded that the most favorable conditions for achieving an optimal functionalization of nylon 6 for antibacterial activity in the dark, by dip coating, were the use of polyol synthesized ZnO NPs at 30 g/L and application of acid surface activation on the nylon, using HCl at low concentrations. Mechanisms were proposed to explain the adherence of ZnO NPs to the nylon textile based on the formation of hydrogen bonds and dipole-dipole bonds between the ZnO NPs and the oxygen and hydrogen atoms from the amide group of the nylon molecules. It was proposed that the acid activation of the nylon surface promoted a hydrolysis of the amide group which led to the formation of carboxyl and amine groups, which in turn resulted in an increase of the potential bonding sites for the ZnO NPs, ultimately achieving a better coating result.