Design of Copper Oxide Nanosheets-Loaded Zeolite with Efficient Inhibition of Marine Bacteria

Copper oxide-loaded zeolite 4A nanocomposites (CuO-zeolite NCs) were successfully prepared by modifying zeolite 4A with CuSO₄ aqueous solution as the copper source. Zeolite 4A showed an important role in hosting copper oxide, and CuO-zeolite NCs exhibited a controlled release of copper ions. XRD patterns confirmed the appearance of new diffraction peaks of copper oxide at 35.83° and 38.83°. CuO nanosheets formed on the surface of zeolite 4A were about 30 – 40 nm thick over a width of 200 – 300 nm. CuO-zeolite NCs were primarily composed of Cu, Si, Al and O, as measured by XPS. Cu 2p_3/2 and Cu 2p_1/2 peaks were fitted into two main peaks centered at 934.7 eV and 954.6 eV, which were attributed to Cu (Ⅱ). Zeolite 4A and CuO-zeolite NC displayed reversible Langmuir isotherm (type-Ⅰ) characteristics and showed maximum adsorption quantities of almost 200 cm³ g⁻¹ at a relative pressure of 1.0 by CO₂ adsorption-desorption experiments. The antibacterial efficiencies of the CuO-zeolite NC were 99.4%, 96.7%, and 96.8% against Pseudoalteromonas tetraodonis (P. tetraodonis), Micrococcus luteus (M. luteus), and Shewanella putrefaciens (S. putrefaciens), respectively. These values showed that nano CuO-loaded zeolite 4A acted as a strong bactericide against marine bacteria. CuO-zeolite NCs can be further applied to marine antifouling coating.