For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed.

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Review on the Processing and Properties of Polymer Nanocomposites and Nanocoatings and Their Applications in the Packaging, Automotive and Solar Energy Fields.

An environmentally friendly, facile, and economical Fe/N co-doped carbonaceous material (Fe-N@C) was prepared by the in-situ pyrolysis of Fe/N rich Enteromorpha biomass for peroxymonosulfate activation and organic contaminants degradation. Results indicated that Enteromorpha-based catalysts prepared at high pyrolysis temperature displayed some highly graphitic nanosheets with rich nitrogen doped. The graphitic N derived from the intrinsic N in Enteromorpha showed the high correlation with the paracetamol (PCM) removal rate; this was confirmed by the Density Functional Theory (DFT) calculation, showing the high adsorption energy (ΔEads, −2.62 eV) of PMS molecular adsorbed onto the graphitic N area. A weak correlation between the PCM removal rate and adsorption capacity was also observed, revealing that the PCM catalytic reaction could be greatly accelerated after the pre-adsorption. It was interesting that the intrinsic Fe in Enteromorpha did not affect the PCM degradation, but PCM removal rate of acid treated Fe-N/C was improved as more active sites were formed after the Fe extraction by acid treatment. Both the radical pathways of O2 − and non-radical 1O2 generated in the Fe-N@C/PMS system were the primary mechanisms for the PCM degradation, which was consistent with the Fukui function values of f° and f- based on the DFT calculation. In addition, high stability of the carbon-based catalysts was observed after three runs and calcinating regeneration, which showed the promising applications for environmental remediation.

In-situ pyrolysis of Enteromorpha as carbocatalyst for catalytic removal of organic contaminants: Considering the intrinsic N/Fe in Enteromorpha and non-radical reaction

Water is an essential part of life and its availability is important for all living creatures. On the other side, the world is suffering from a major problem of drinking water. There are several gases, microorganisms and other toxins (chemicals and heavy metals) added into water during rain, flowing water, etc. which is responsible for water pollution. This review article describes various applications of nanomaterial in removing different types of impurities from polluted water. There are various kinds of nanomaterials, which carried huge potential to treat polluted water (containing metal toxin substance, different organic and inorganic impurities) very effectively due to their unique properties like greater surface area, able to work at low concentration, etc. The nanostructured catalytic membranes, nanosorbents and nanophotocatalyst based approaches to remove pollutants from wastewater are eco-friendly and efficient, but they require more energy, more investment in order to purify the wastewater. There are many challenges and issues of wastewater treatment. Some precautions are also required to keep away from ecological and health issues. New modern equipment for wastewater treatment should be flexible, low cost and efficient for the commercialization purpose.

Role of Nanomaterials in the Treatment of Wastewater: A Review

There has been a considerable amount of research in the development of sustainable water treatment techniques capable of improving the quality of water. Unavailability of drinkable water is a crucial issue especially in regions where conventional drinking water treatment systems fail to eradicate aquatic pathogens, toxic metal ions and industrial waste. The research and development in this area have given rise to a new class of processes called advanced oxidation processes, particularly in the form of heterogeneous photocatalysis, which converts photon energy into chemical energy. Advances in nanotechnology have improved the ability to develop and specifically tailor the properties of photocatalytic materials used in this area. This paper discusses many of those photocatalytic nanomaterials, both metal-based and metal-free, which have been studied for water and waste water purification and treatment in recent years. It also discusses the design and performance of the recently studied photocatalytic reactors, along with the recent advancements in the visible-light photocatalysis. Additionally, the effects of the fundamental parameters such as temperature, pH, catalyst-loading and reaction time have also been reviewed. Moreover, different techniques that can increase the photocatalytic efficiency as well as recyclability have been systematically presented, followed by a discussion on the photocatalytic treatment of actual wastewater samples and the future challenges associated with it.

https://iopscience.iop.org/article/10.1088/1361-6528/aac6ea/pdf

Heterogeneous photocatalysis and its potential applications in water and wastewater treatment: a review

Visible-light activation of persulfate by TiO2/g-C3N4 photocatalyst toward efficient degradation of micropollutants

The incorporation of nanostructured photocatalysts in polymers is a strategic way to obtain novel water purification systems. This approach takes the advantages of: (1) the presence of nanostructured photocatalyst; (2) the flexibility of polymer; (3) the immobilization of photocatalyst, that avoids the recovery of the nanoparticles after the water treatment. Here we present ZnO-polymer nanocomposites with high photocatalytic performance and stability. Poly (methyl methacrylate) (PMMA) powders were coated with a thin layer of ZnO (80 nm thick) by atomic layer deposition at low temperature (80 °C). Then the method of sonication and solution casting was performed so to obtain the ZnO/PMMA nanocomposites. A complete morphological, structural, and chemical characterization was made by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses. The remarkable photocatalytic efficiency of the nanocomposites was demonstrated by the degradation of methylene blue (MB) dye and phenol in aqueous solution under UV light irradiation. The composites also resulted reusable and stable, since they maintained an unmodified photo-activity after several MB discoloration runs. Thus, these results demonstrate that the proposed ZnO/PMMA nanocomposite is a promising candidate for photocatalytic applications and, in particular, for novel water treatment.

Novel synthesis of ZnO/PMMA nanocomposites for photocatalytic applications.

Preferential removal of pesticides from water by molecular imprinting on TiO2 photocatalysts

Molecularly imprinted polymer for selective adsorption of diclofenac from contaminated water

This work reports on the ZnO thin films obtained by atomic layer deposition (ALD), at a deposition temperature down to 40 °C The crystallinity of the material as a function of the film thickness and the deposition temperature was investigated The photocatalytic performance was evaluated by the degradation of methylene blue (MB) dye in water under UV light irradiation The effect of the film thickness and the deposition temperature on the photocatalysis was deeply elucidated Once the optimized conditions (in terms of thickness and temperature) were found, the ALD process was transferred on a flexible polymeric substrate: polyethylene naphthalate (PEN) The photo-activity of the flexible materials was evidenced by the degradation of MB and phenols in water The results demonstrate that low temperature growth by ALD can be fruitfully applied to synthesize flexible materials that can found applications in photocatalysis

Low temperature atomic layer deposition of ZnO: Applications in photocatalysis

Photocatalysis-based technologies are currently striving to find a methodology able to selectively catch, and degrade specific organic contaminants. To solve this problem, we propose molecularly imprinted ZnO nanonuts as new nanomaterial. In this work, ZnO have been imprinted, through a chemical method, with one of the most diffused analgesic-antipyretic drugs: acetaminophen (commonly called “paracetamol”), today considered as an emergent environmental pollutant. The molecularly imprinted nanonuts have been characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) adsorption-desorption of N2, X-ray diffraction analyses (XRD), high-resolution transmission scanning electron microscopy (HR-S/TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Thanks to the accurate performed characterization, the interaction between ZnO and paracetamol has been elucidated. The photodegradation of paracetamol in aqueous solution has been demonstrated under UV light irradiation. The selectivity of the photodegradation process has been additionally investigated thanks to the comparison with the degradation of methyl orange (MO) and phenol, another two common water pollutants. Imprinted ZnO nanonuts have shown a great affinity and selectivity for the paracetamol, being able to degrade all the paracetamol present in the solution in 3 h. This work offers a new, economic, and easy way to prepare molecularly imprinted ZnO nanonuts with high specificity, relevant in the contexts of environmental protection.

Maria Cantarella

Papers

Novel synthesis of ZnO/PMMA nanocomposites for photocatalytic applications.

Preferential removal of pesticides from water by molecular imprinting on TiO2 photocatalysts

Molecularly imprinted polymer for selective adsorption of diclofenac from contaminated water

Low temperature atomic layer deposition of ZnO: Applications in photocatalysis

Selective photodegradation of paracetamol by molecularly imprinted ZnO nanonuts