Ag/ZnO/PMMA Nanocomposites for Efficient Water Reuse

Abstract

This work attempts to produce photocatalytic surfaces for large-scale applications by depositing nanostructured coatings on polymeric substrates. ZnO/poly(methyl methacrylate) (PMMA) composites were prepared by low-temperature atomic layer deposition (ALD) of ZnO on PMMA substrates. In addition, to increase the photocatalytic and antibacterial activities of ZnO films, Ag nanoparticles were added on ZnO surfaces using plasma-enhanced ALD. The morphology, crystallinity, and chemical composition of the specimens were meticulously examined by scanning and transmission electron microscopies, energy-dispersive Xray spectroscopy, and X-ray diffraction analyses. The noteworthy photocatalytic activity of the nanocomposites was proved by the degradation of the following organic pollutants in aqueous solution: methylene blue, paracetamol, and sodium lauryl sulfate. The antibacterial properties of the samples were tested using Escherichia coli as a model organism. Moreover, the possible toxic effects of the specimens were checked by biological tests. The present results unambiguously indicate the Ag/ZnO/PMMA nanocomposite as a powerful tool for an advanced wastewater treatment technology.

Is Poly(methyl methacrylate) (PMMA) a Suitable Substrate for ALD?: A Review

“…Di Mauro et al explored ZnO/PMMA and Ag/ZnO/PMMA nanocomposites as photocatalyst materials for the degradation of pollutants and water reuse upon UV light illumination [ 60 , 61 , 62 ]. The authors used different forms of PMMA i.e., commercial PMMA powders (0.2–1 mm in diameter) and plates of PMMA (4 mm thick), and kept the deposition temperature at 80 °C, a temperature compatible with the thermal stability of the PMMA polymer which enabled the growth of polycrystalline ZnO wurtzite [ 60 , 61 , 62 ]. After the photocatalytic degradation tests, where an organic dye (methylene blue) was used as a model pollutant, the ZnO on the PMMA nanocomposites demonstrated excellent photo-stability [ 62 ].…”

“…After the photocatalytic degradation tests, where an organic dye (methylene blue) was used as a model pollutant, the ZnO on the PMMA nanocomposites demonstrated excellent photo-stability [ 62 ]. The addition of Ag to the ZnO/PMMA nanocomposites brought new features to the nanocomposite, in terms of improving the photocatalytic efficiency allowing degradation tests of other organic contaminants (e.g., paracetamol drug, sodium lauryl sulfate), besides methylene blue [ 61 ]. Figure 11 a shows the X-ray diffraction (XRD) patterns of the ZnO/PMMA composite after the degradation tests, where it is possible to observe that ZnO remained stable, maintaining the wurtzite crystallographic structure [ 62 ].…”

“…Figure 11 a shows the X-ray diffraction (XRD) patterns of the ZnO/PMMA composite after the degradation tests, where it is possible to observe that ZnO remained stable, maintaining the wurtzite crystallographic structure [ 62 ]. On the other hand, Figure 11 b reveals the degradation of pharmaceuticals considered as emerging contaminants by the Ag/ZnO/PMMA nanocomposite, under UV illumination [ 61 ]. In summary, these nanocomposites were stable and reusable in the degradation of organic pollutants and are easy to prepare and to recover after being tested.…”

Innovative Polymeric Hybrid Nanocomposites for Application in Photocatalysis

“…A further step towards a superior photocatalytic performance is represented by the enrichment of ZnO/PMMA nanocomposites with Ag nanoparticles [ 65 ]. Besides the antibacterial properties of Ag [ 66 ], the combination of the semiconductor photocatalysts with electron scavengers such as noble metals (e.g., Ag, Au and Pt) increases the separation between the photoexcited electrons and holes, thus reducing their recombination rate, which is one of the main shortcomings of the semiconductor photocatalysts.…”

“… ( a ) Scanning transmission electron microscopy (STEM) image of Ag NPs on the ZnO surface and energy-dispersive X-ray spectroscopy (EDS) signals from silver, zinc, and oxygen; ( b ) degradation of MB, paracetamol, and SDS after 4 h under UV irradiation for blank solutions, in the presence of ZnO/PMMA, and in the presence of Ag/ZnO/PMMA; ( c ) bacterial survival percentage in the dark and when exposed to UV irradiation for 1 h in contact with PMMA, ZnO/PMMA, and Ag/ZnO/PMMA samples [ 65 ]. …”