Enhanced antibacterial activity, dye rejection and anti-fouling performance of ZrO2-SiO2 composite ceramic membranes embedded by silver nanoparticles

The ceramic membranes hold significant promise for dye wastewater treatment, owing to their exceptional water permeability, mechanical strength, and chemical stability. However, membrane fouling causes undesired filtration performance. In this study, the Ag/ZrO2-SiO2 composite ceramic membranes with varying molar ratios of Ag/Si (n(Ag)) were fabricated by incorporating AgNO3 into the ZrO2-SiO2 matrix using the sol-gel method. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements revealed that the doped Ag element exists in the form of metallic Ag-0 nanoparticles (AgNPs). The introduction of AgNPs was found to optimize the surface microstructure and control the charge properties of the membrane, thus enhancing the dye rejection performance of Ag/ZrO2-SiO2 membranes under various filtration conditions. The effect of n(Ag) was studied to establish an optimal balance between antibacterial activity and dye rejection performance. The optimized Ag-0.1/ZrO2-SiO2 (n(Ag )= 0.1) materials displayed superior antibacterial activity evidenced by antibacterial efficiency of 98.86% against Escherichia coli and 97.42% against Staphylococcus aureus. Furthermore, the Ag-0.1/ZrO2-SiO2 membrane exhibited a remarkable rejection of 96.74% and a flux of 331.36 L m(-2) h(-1) for 50 mg L-1 reactive black KN-B solution at 2 bar and 25 degrees C. Compared to the ZrO2-SiO2 membrane, the Ag-0.1/ZrO2-SiO2 membrane indicated enhanced rejections of the five dyes with various molecular weights along with excellent anti-fouling performance of reactive black KN-B with a flux recovery of 91.18% after three anti-fouling filtration cycles. This study highlights the potential of the Ag/ZrO2-SiO2 membrane for effective dye wastewater treatment.