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M. N. A. MOHAMMAD TAIB ET AL.
picking velocity. In another study by Sobri et al. (Sobri et al. 2021), they investigated the use of nano ZnO on bamboo bleached pulp to produce antibacterial paper. The zinc percentages varied from 15.08% to 34.08%, while the oxygen percentages varied from 17.45% to 32.59%. The result showed that a high percentage of precursors exhibited a more amorphous structure, and a 30% increase in the inhibition zone was reported for 10.00 mm to 25.00 mm against S. aureus, S. choleraesuis and E. coli . Precursors higher than 0.3 M enhanced the growth of zinc oxide, providing better antibacterial properties. ZnO possesses remarkable optical and chemical characteristics, making it highly versatile for a wide array of applications. It is particularly renowned for its antimicrobial capabilities and ability to protect against UV radiation (Brayner et al. 2006). Numerous methods have been recorded for producing ZnO nanoparticles. These methods consist of chemical vapor deposition, gas-phase procedures, spray pyrolysis, hydrothermal synth- esis, micro-emulsion, electrochemical approaches, pulsed laser deposition, microwave synthesis, and the sol-gel method (Darroudi et al. 2013). However, the conventional approach for synthesizing ZnO nanoparticles is expensive, poses environ- mental hazards, and can also result in the presence of toxic substances adsorbed on the surface of the nanoparticles, which could potentially have harmful effects on living substances. A green technology approach offers a solution to this problem, where ZnO nanoparticles can be synthesized using microorgan- isms or plants, resulting in biocompatible nanoparticles (Nava et al. 2017). The nano ZnO has varied structures such as rods, prisms, needles, sheets, triangles, wires, squares, ribbons, tubes, and combs (Sobri et al. 2021). It also exists in two- or three-dimensional structures. The structures depend on the production methods for nanoscale ZnO, such as vapor deposition micro- emulsion, the sol-gel process, hydrothermal, and precipitation (Kołodziejczak-Radzimska and Jesionowski 2014; Stoimenov et al. 2002). The image in Figure 7 depicts the morphology of ZnO at two distinct concentrations that are 10 mL and 40 mL. In the case of lower concentration (a), the particles appear non-uniform, displaying uneven shapes and sizes. Conversely, the higher concentration of CSE in (b) yields a more uniform material characterized by well-defined, rounded particles, predominantly of similar size and shape. These particles have an average diameter of 8 ± 0.5 nm. Characterization. The inclusion of ZnO nanoparticles in paper leads to a significant reduction (22.2%) in the tensile index compared to the unloaded with ZnO paper. A similar phenomenon is observed in the tear index, with a decrease of 46.23% for paper loaded with ZnO nanoparticles compared to the control paper. This reduction of mechanical properties is attributed to the presence of fillers that impact the bonding between fibers. Table 5 shows the mechanical properties of control paper and paper loaded with nano ZnO. Application. Nano ZnO has substantial potential in the paper industry, offering a wide range of benefits. It has antibacterial properties, especially against Escherichia coli , and it also gets rid of bacteria that cause bad odors (Lebaka et al. 2025). The utilization of nano ZnO in the paper industry represents a promising avenue
Figure 7. Morphology of the ZnO NPs: (a) 10 mL and (d) 40 mL (Nava et al. 2017).
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