Waste eggshell membrane-templated CuO-ZnO nanocomposites with enhanced adsorption, catalysis and antibacterial properties for water purification

In the present work, we synthesized CuO-ZnO (CZ) nanocomposites using a bio-templated method from biowaste-eggshell membranes (ESM). Results showed that CZ-ESM nanocomposites of morphology and structure preserved the original structural characteristics of ESM with interlaced network coated by small inorganic nanoparticles. In addition, the samples exhibit excellent adsorption, catalysis and antibacterial activities. Experimental results showed the adsorption kinetics and isotherm were well described by pseudo-second order kinetics and Langmuir isotherm model for Congo red dye, the maximum adsorption capacity was determined to be 775 mg•g⁻¹. The catalysis reduction efficiency of CZ-ESM nanocomposites for 4-nitrophenol (4-NP) reached 98% after 12 min at room temperature. CZ-ESM could be recycled several times without any significant activity loss. Furthermore, the results of antibacterial experiments indicated that CZ-ESM nanocomposites exhibited a strong inhibition activity against E. coli and S. aureus. The maximum diameter of the inhibition zone was 27.5 mm for S. aureus and 20.3 mm for E. coli.