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Despite the tremendous progress in the development of functional materials from plastic waste to promote its recycling, only a few examples of hydrogel materials from plastic waste were reported. In this study, microwave-assisted depolymerization of waste PET plastic using polyamine was performed to prepare short aminophthalamide oligomers followed by chemically cross-linking into a hydrogel material. Catalyst-free microwave-assisted aminolysis of PET was completed within 30–40 s, demonstrating high efficiency of the depolymerization reaction. Subsequent epoxy cross-linking of the oligomers yielded a hydrogel with a swelling degree of ca. 92.1 times in pure water. The application of the obtained hydrogel for the removal of copper ions (Cu2+) from water was demonstrated. Efficient complexation of NH2 groups of the hydrogel with Cu2+ resulted in high adsorption capacities of the hydrogel material toward Cu2+ removal, which were the highest at neutral pHs and reached ca. 213 mg/g. The proposed type of environmental material is beneficial owing to its waste-derived nature and functionality that can be applied for the high-efficiency removal of a broad scope of known environmental pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel method of waste plastics conversion to a matrix for metal NPs was proposed. • Waste PET was converted to a hydrogel matrix for the synthesis of Au and Ag NPs. • Hydrogel plays a dual role of reductant and matrix for Au or Ag NPs growth. • Application of the hybrid hydrogel as a catalyst was demonstrated. • Hybrid hydrogel with NPs shows high reusability after four catalytic reactions. The progressive accumulation of discarded plastic in the environment demands further development of waste management of plastic waste and conversion technologies of such waste to value-added materials. Recently, the conversion of plastic waste to functional materials via chemical recycling has attracted considerable attention. In this report, plastic waste (PET) was utilized for the preparation of a hydrogel-based catalyst via a cross-linking reaction of PET-derived oligo(terephthalamide)s followed by the electroless metallization. The polymeric matrix of PET-derived hydrogel plays multiple roles of (i) an adsorption media for noble metal ions such as Au3+ and Ag+, (ii) a reducing agent of Au3+ and Ag+ ions to Au0 and Ag0, and (iii) a matrix for the controlled growth of Au and Ag nanoparticles (AuNPs and AgNPs). The obtained hybrid hydrogels after metallization contained well-dispersed AuNPs and AgNPs of 6.1 ± 3.7 nm or 6.1 ± 1.4 nm size, respectively. The catalytic activities of the hybrid hydrogels with metal nanoparticles were studied in a model system of p -nitrophenol reduction in an aqueous solution. The hybrid materials of both Au@hydrogel and Ag@hydrogel were catalytically active for the reduction of p -nitrophenol, obeying the first-order kinetics. Importantly, the AuNPs or AgNPs in the hydrogel matrix preserved the original catalytic activity after multiple p -nitrophenol reduction reactions, showing a promising reusability of the catalysts. The proposed here approach aims to broaden the scope of conversion routes of plastic waste to value-added materials as well as to develop new types of polymeric matrices for templating and growth of metal nanoparticles for catalytic applications. [ABSTRACT FROM AUTHOR]

Accumulation of mismanaged plastic in the environment and the appearance of emerging plastic-derived pollutants such as microplastics strongly demand technologies for waste plastic utilization. In this study, polyethylene terephthalate (PET) from waste plastic bottles was directly utilized to prepare a matrix of an adsorbent for cesium (Cs+) removal. The organic matrix of PET-derived oligomers obtained by aminolysis depolymerization was impregnated with bentonite clay and magnetite nanoparticles (Fe 3 O 4 NPs), playing the roles as a major adsorptive medium for Cs+ removal and as a functional component to primarily provide efficient separation of the hybrid adsorbent from aqueous system, respectively. The obtained hybrid composite microparticles were next tested as an adsorbent for the removal of Cs+ cation from aqueous solutions. The adsorption process was characterized by fast kinetics reaching ca. 60% of the equilibrium adsorption capacity within 5 min and the maximum adsorption capacity toward Cs+ was found to be 26.8 mg/g. The adsorption process was primarily dominated by the cationic exchange in bentonite, which was not significantly affected by the admixture of the competing mono- and divalent cations (Na+, K+, and Mg2+). The proposed approach here exploits the sustainable utilization scenario of plastic waste-derived material to template complex multifunctional nanocomposites that can find applications for pollution cleaning and environmental remediation. [Display omitted] • A novel method of waste PET conversion to a matrix for bentonite was proposed. • Microparticles were prepared by PET aminolysis and co-precipitation with bentonite. • Fe 3 O 4 NPs were utilized to confer the hybrid microparticles with magnetic property. • Application of hybrid magnetic microparticles for cesium removal was demonstrated. • Adsorption capacity of hybrid magnetic microparticles for cesium was ca. 26.8 mg/g. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is a mass-produced plastic material widely used for the manufacturing of bottles, textile fibers, and other products. The mismanaged plastic problem and the associated environmental pollution urge the development of waste plastic utilization methods based on mechanical, chemical, and energy recycling. Basic technologic processes of PET chemical recycling, that have been established decades ago, were substantially extended by recent efforts of chemists and chemical engineers toward new materials based on PET-derived traditional as well as novel chemical feedstocks. This review summarizes and systematizes reported approaches and recycling protocols for waste PET conversion into functional materials based on PET-derived chemical feedstocks and gives an overview of their application fields. [Display omitted] • Recent progress in the conversion of waste PET to functional materials is reviewed. • New waste PET-derived chemical feedstocks support versatile materials design. • PET-derived materials target construction, coatings, adsorbents, catalysis, and energy sectors. • PET-derived alternatives hold increasing promise for substituting of oil-based raw chemicals. [ABSTRACT FROM AUTHOR]

Mass production and consequent accumulation of plastic wastes in the environment urges the development of technologies for the efficient plastic wastes utilization and valorization to materials and products to support circular economy. Here, we report a novel conversion of PET plastic to a magnetic microparticles adsorbent prepared by co-precipitation of Fe 3 O 4 nanoparticles with oligomeric products of PET aminolysis. The obtained adsorbent represents highly water-dispersible oligo(terephthalamide) particles of several tens μm size embedding magnetic nanoparticles randomly distributed in the organic matrix. The PET-derived magnetic adsorbent was used for the rapid and facile magnetic separation of an anionic dye (Congo Red, CR) from dye simulated water samples. The adsorbent containing plenty of amine groups showed superb adsorption capacity for CR of ca. 780 mg/g which is pH dependent and optimal at pH 6.5. Furthermore, the microparticular, non-aggregative state of the adsorbent coupled with its magnetic functionality provided rapid saturation of the adsorbent with dye by ca. 70% of the equilibrium adsorption capacity within 5 min and possibility of instantaneous removal from solution by a magnet. The proposed here material design addresses simultaneously the problem of plastic wastes utilization and preparation of cost-effective and efficient adsorbents for environmental cleaning purposes. [Display omitted] • A new strategy of waste plastic converting to functional adsorbent material was proposed. • Magnetic microparticles were prepared by PET aminolysis and co-precipitation with Fe 3 O 4 NPs. • Application of PET-derived magnetic microparticles as an adsorbent was demonstrated. • Adsorption capacity of magnetic microparticles for Congo Red dye was ca. 780 mg/g. • 66.7% of the saturation capacity of an adsorbent was reached within 1 min. [ABSTRACT FROM AUTHOR]

While the possibility of waste bottles' PET conversion to fluorescent materials has been recently demonstrated, optimization of the conversion protocol based on rational material design may greatly enhance key characteristics of the upcycled material. In this study, conversion of PET to fluorescent nanomaterials by means of hydrothermal (HT) treatment of PET and products of PET pyrolysis, glycolysis, and aminolysis in the presence and in the absence of an oxidizing agent was systematically investigated to compare fluorescent properties of HT products. Among studied conversion routes, the direct HT conversion of PET or a combination of the HT treatment with the PET pre-treatment by either pyrolysis or glycolysis resulted in non-fluorescent of weakly fluorescent products, whereas aminolysis of PET bottle plastics followed by the HT treatment of the aminolysis products increased dramatically, up to tens to hundreds fold, the fluorescence of the products. Admixing of several percent of an oxidant, H 2 O 2 , to HT mixture further enhanced the product fluorescence yielding fluorescent nanoparticles (nitrogen-doped carbon dots, NCDs) with 25.3% conversion yield and the quantum yield of 9.1%. Based on 1H and 13C NMR, FTIR, XPS, and Raman spectroscopy data, the mechanism of NCDs formation was proposed. The N-doped carbon dots obtained by waste PET upcycling were used for detection and quantification of Cu2+ ion at ppm and Fe3+ ion at ppb concentrations. [Display omitted] • Conversion of PET to fluorescent materials by combining hydrothermal treatment and various pretreatment reactions was studied. • Pretreatment of PET using aminolysis greatly enhances the fluorescence of the material after hydrothermal treatment. • Hydrothermal treatment of the aminolysis product of PET in aqueous H 2 O 2 yields N-doped carbon dots. • The mechanism of N-doped carbon dots formation and their structure were proposed. • N-doped carbon dots can be used for detecting Fe3+ in aqueous solutions at ppb level and Cu2+ at ppm level. [ABSTRACT FROM AUTHOR]

To ensure sustainable use of natural resources and circulation of materials, efficient methods of waste plastic conversion into value chemicals and scenarios for utilization of the latter are increasingly demanded. Here, we propose a method of waste PET bottles conversion to cross-linked hydrogels through PET aminolysis using tri- and tetraamines as a method of plastic waste valorization. Water-soluble oligomeric products of PET aminolysis were cross-linked in water using diglycidyl ether to get mechanically stable hydrogels that show typical polyelectrolyte behavior of polycations. PET-derived hydrogels abundant with amino groups and aromatic moieties were tested as adsorbents for an anionic dye such as Congo Red, and their absorption capacity towards dye was found to be ca. 500 mg/g. Beside demonstrated here application of PET-derived hydrogels for water cleaning from an industrial dye, utilization of such hydrogel materials in fields of environment, agriculture, separation, etc. are also anticipated. [Display omitted] • Waste PET bottles can be converted to a hydrogel material by aminolysis and cross-linking. • Aminolysis reaction of PET and triamines or tetraamines yields water-soluble oligomeric terephthalamides. • Cross-linking of PET aminolysis products using ethylene glycol diglycidyl ether can be used to prepare hydrogels. • Application of PET-derived hydrogel as an industrial dye adsorbent was demonstrated. • Adsorption capacity of PET-derived hydrogel for Congo Red anionic dye was ca. 500 mg/g. [ABSTRACT FROM AUTHOR]

The large accumulation and low recycling rates of polyolefin waste have posed a threat to the environment and human health. The shortage of chemical recycling methods for polyolefins strongly demands the development of new and sustainable treatment technologies for hydrocarbon plastics to improve their waste management. In this study, polyethylene (PE) and polypropylene (PP) were utilized for the preparation of multi-color polymer carbon dots (PCDs) via a two-step hydrothermal (HT) synthesis involving (i) thermo-oxidative degradation of polyolefins to precursors containing plentiful oxygen-based functional groups, and (ii) modification with phenylenediamine (PDA). The fluorescence of PCDs depends on the structure of isomeric PDA and PCDs modified by ortho -, meta -, and para -PDA emit blue, green, and yellow color fluorescence, respectively. The formation mechanism of PCDs, involving dehydrative condensation and amination of PE or PP-derived precursors by PDA, was proposed. The obtained PCDs were utilized for the detection and quantification of Fe3+ ions at ppm concentrations. The proposed strategy here aims to broaden the scope of the chemical recycling methods for polyolefin plastic waste as well as to develop a conversion route of polyolefin to value-added materials. [Display omitted] • PE or PP was converted to multi-color polymer carbon dots via two-step hydrothermal synthesis. • Hydrothermal decomposition of PE or PP in H 2 O 2 results in the formation of ca. 10 nm PCDs. • PCDs from PE or PP can be functionalized by hydrothermal reaction with phenylenediamines. • The fluorescence color of functionalized PCDs depends on the structure of phenylenediamines. • Fluorescent PCDs from PE and PP can be used for the detection of Fe3+ and Hg2+ in water. [ABSTRACT FROM AUTHOR]