Commercialization potential of PET (polyethylene terephthalate) recycled nanomaterials: A review on validation parameters

Polyethylene Terephthalate (PET) is a polymer which is considered as one of the major contaminants to the environment. The PET waste materials can be recycled to produce value-added products. PET can be converted to nanoparticles, nanofibers, nanocomposites, and nano coatings. To extend the applications of PET nanomaterials, understanding its commercialization potential is important. In addition, knowledge about the factors affecting recycling of PET based nanomaterials is essential. The presented review is focused on understanding the PET commercialization aspects, keeping in mind market analysis, growth drivers, regulatory affairs, safety considerations, issues associated with scale-up, manufacturing challenges, economic viability, and cost-effectiveness. In addition, the paper elaborates the challenges associated with the use of PET based nanomaterials. These challenges include PET contamination to water, soil, sediments, and human exposure to PET nanomaterials. Moreover, the paper discusses in detail about the factors affecting PET recycling, commercialization, and circular economy with specific emphasis on life cycle assessment (LCA) of PET recycled nanomaterials.

Effect of Polymer Waste Mix Filler on Polymer Concrete Composites

The hazards of polymer waste and emitted gas on the environment pose a global challenge. As a trial to control this, the current work aims to reuse the polymer waste mix (PM) as fillers in calcium silicate to prepare new composites of environmentally friendly polymer concrete. PM was first subjected to treatment to obtain treated PM (TPM) and then was filled in new dicalcium silicate cement with different concentrations. The microstructural characterizations declare the successful preparation of the dicalcium silicate base material. After the curing reaction, the precipitated carbonate main product is responsible for the gained properties. The CO2 uptake% in the proposed composites reached 16.6%, referring to the successful storage of CO2 gas during curing. The treatment reaction led to an increase in the flexural and compression strengths due to the strengthening of the polymer waste mix-cement interface; the strengths were increased gradually with more contents of TPM fillers. 7% TPM-cement concentration achieved the highest flexural strength and compression strength of10.2 and 12.7%, respectively, compared with blank cement. The used polymer improved slightly the pull-off force of the prepared cement, and 7 and 5% TPM-cement composites have the maximum values. All the proposed composites passed the impact testing without failure, where the combination between the polymer waste and silicate cement resulted in a stable composite surface. Compared with the blank, the different concentrations of TPM-cement composites show more stability against water absorption. In addition, the proposed composites and blank cement have a very low carbon dioxide emission. The ability to recycle the polymer waste, form new type of low-energy silicate, improve the mechanical and surface properties, uptake CO2 gas, and reduce gas emission makes the proposed polymer waste mix-cement composites as environmentally friendly construction products.

Catalytic ozonation of phenol by ZnFe2O4/ZnNCN: performance and mechanism

A novel magnetic catalyst was synthesized and applied in heterogeneous catalytic ozonation process. The ZnFe₂O₄/ZnNCN material was synthesized by hydrothermal and high-temperature calcination method and characterized by XPS, XRD, FTIR, VSM, and SEM techniques. In the system of O₃/ZnFe₂O₄/ZnNCN, the removal rates of phenol and chemical oxygen demand (COD) reached 93% and 43% at 60 min. Further analysis shows that ZnFe₂O₄/ZnNCN has a significant catalytic effect on O₃, which is demonstrated by the first-order kinetic constant being 1.93 times than O₃ alone. The catalyst exhibits excellent cycling stability during repeated catalytic ozonation process and can be fully recycled under an applied magnetic field. The role of hydrogen peroxide (H₂O₂) and surface hydroxyl groups was investigated, and a mechanism for catalytic ozonation was proposed. This work not only builds an efficient catalytic ozonation system, but also provides a potential modification strategy for spinel oxides.

Potential contribution of nanotechnolgy to the circular economy of plastic materials

The problem of plastic accumulation in the environment requires the development of effective strategies to shift the paradigm of used plastics from wastes to resources. In the present contribution, after an overview of the current plastic management strategies, the possible role of nanotechnology to this emerging field is considered. In particular, the challenges related to the use of nano-additives to improve the properties of recycled plastics is discussed based on the fundamental aspects of colloid stabilisation. Finally, the contribution of nanotechnology to the fabrication of effective catalysts for the depolymerisation of plastics into the constituent monomers is outlined.

The use of nanoadditives within recycled polymers for food packaging: Properties, recyclability, and safety

Nanotechnology is considered a highly valued technology to reduce the current environmental problem that is derived from plastic accumulation. The need to recycle and reuse packaging materials is essential to create a sustainable society towards a circular economy. However, the reprocessing of polymers leads to the deterioration of their characteristic mechanical, optical, thermal, and barrier properties due to the degradation of their polymeric chains. When recycled polymers are reinforced with nanoadditives, aforementioned properties improve and their use in the circular economy is more viable. In this review, different types of nanoadditives and recent advances in the development of recycled polymer nanocomposites reinforced with nanoadditives will be presented. In addition, there is a description of two research topics of current interest, recyclability of nanocomposites and safety for food packaging applications. Recyclability of nanocomposites requires a study that includes the nature of the polymer matrix, the type of polymer and the concentration of nanofiller, the morphology, the presence of additives, and the conditions of the thermal-mechanical cycles. Finally, safety section is dedicated to clarify the migration process in nanoreinforced-recycled polymers in order to assess their safety for food contact applications.

Sonochemical synthesis of PVA/PVP blend nanocomposite containing modified CuO nanoparticles with vitamin B1 and their antibacterial activity against Staphylococcus aureus and Escherichia coli

The aim of this paper was to blend the polymers, poly(N-vinyl-2-pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) to produce a novel composite materials possessing the benefits of both. CuO nanoparticles (NPs) were used as a suitable filler to fabricate the blend nanocomposites (NCs) with desired properties. First, the surface of NPs, was modified with vitamin B₁ (VB₁) as a bio-safe coupling agent. Then, the blend NCs with various ratios of modified CuO (3, 5, and 7 wt%) were fabricated under ultrasonic irradiations followed by casting/solvent evaporation method. These processes are fast and green way to disperse the NPs sufficiently. Several techniques were applied for the characterization of the obtained NCs. morphology examination demonstrated the morphology of NCs and compatibility of NPs with the blend polymer. EDX results indicated the weight and atomic percentage of the achieved materials. TGA analysis verified that the NCs show higher thermal properties than the neat blend polymer. Also embedding the modified NPs into the blend polymer had effected on optical absorbance of the obtained NCs. The contact angle measurements confirmed that the hydrophilicity decreased for different proportions of the modified NPs loaded in the blend polymer. Finally, NCs show better bactericidal effects against gram-positive than gram-negative bacteria.

Sonochemical assisted synthesis and characterization of magnetic PET/Fe3O4, CA, AS nanocomposites: Morphology and physiochemical properties

Ultrasonic-assisted synthesized iron oxide (Fe₃O₄) nanoparticles (NP)s were modified with biodegradable citric acid (CA) and ascorbic acid (AS) [vitamin C] as capping agents. The ultrasonication (US) was applied for the synthesis and modification process as an easy, safe and fast method. Dissolution/reprecipitation procedure was offered to recycle poly(ethylene terephthalate) (PET) bottles and then, it has been focused on the preparation of PET nanocomposites (NC)s based on solution method via sonication agitation to disperse the Fe₃O₄, CA, AS NPs in the organic polymeric surrounding substance. Magnetic PET NCs with modified Fe₃O₄ NPs loading (1, 3, and 5wt%) were fully characterized and the effect of NPs was examined by focusing on four aspects: Fourier transform infrared spectroscopy, X-ray diffraction, thermal stability studies, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Also, flame retardant behaviors of the NCs were investigated. Achieved morphology pictures displayed the presence of well dispersed magnetic NPs in the polymer matrix at nano-scale. In this work after recycling of PET waste bottles, it was aim to have magnetic PET due to its various potential applications such as wastewater treatment, catalysts, biomedicine and drug delivery system and electromagnetic devises. It was also intention to show easy, time saving and safe way (US method) to have magnetic PET which was achieved. From the results it can be concluded that one can readily have good dispersion of magnetic NPs in the PET matrix.