Antibacterial finishing of textile materials using modified bentonite

Direct application of heavy metals as antibacterial agents can cause skin irritations and discoloration of the tissue and it can result in short-term applicability. One of the ways to solve these problems is to immobilize these agents on bentonite. Treatment of textile materials with such activated bentonite for use in various branches of industry has attracted the attention of many researchers in recent years. The objective of the present study was to develop a potential use of Cu- and Zn-modified bentonites as antibacterial finishing agents for two textile materials, non-woven textile (NT) and knitted fabric (PL). The bentonite samples were characterized using ED-XRF (energy dispersive X-ray fluorescence spectrometry), XRPD (X-ray powder diffraction), SEM (scanning electron microscopy), FTIR (Fourier-transform infrared spectroscopy), and BET (N2 adsorption-desorption) analyses. SiO2 and Al2O3 oxides were the main components of all bentonite samples indicated by ED-XRF analysis, while the XRPD analysis confirmed that the natural bentonite (NB) consisted of montmorillonite (Mnt) as the dominant mineral (peaks at 6.94, 19.94, 35.09, and 54.09 degrees 2 theta) and small amounts of quartz and calcite. A reduction in the basal plane spacing, d001, of Mnt occurred in Cu/Zn-B1, Cu/Zn-B3, and CuB, while in Cu/Zn-B2 and ZnB the basal spacing increased. Also, the size and form of particles and porosity changed, which was confirmed by the BET analysis. Modified bentonite samples experienced a reduction in the specific surface area and total pore volume, as well as movement of the middle mesopore diameter toward the larger diameters. The Zn-modified bentonite demonstrated a greater antibacterial effect on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus than Cu- and Na-modified bentonite samples with a MIC (minimum inhibitory concentration) of 0.94 mg/mL, while among Cu/Zn bentonite samples, Cu/Zn-B2 had the strongest antibacterial effect (MIC 0.47 mg/mL). Cu/Zn-B2 was integrated on NT and PL using a screen printing method and showed good antibacterial activity. The printed NT showed better activity than printed PL, and increasing the concentration of applied Cu/Zn-B2 also increased the antibacterial properties.