Waste Polyethylene Terephthalate Research Articles

Optimization of Ti-PA efficiently catalytic the alcoholysis of waste PET using response surface methodology.

A new type of titanium phthalate (Ti-PA) catalyst was prepared by exchange method of phthalic acid and isopropyl titanate, which is never been reported before. The Ti-PA catalyst was characterized by FT-IR, TG, Uv-vis, BET, SEM, and EDS. The Ti-PA catalyst shows good catalytic activity in the alcoholysis reaction of polyethylene terephthalate (PET) and optimal experimental conditions for the alcoholysis process were optimized by response surface methodology; the Ti-PA catalyst provided a BHET yield of 81.98% for reaction lasting 3.98h at 191°C of 0.86% catalyst and 13.7ml ethylene glycol; the model has good reliability. The kinetics and reaction mechanism of the process were explored and apparent activation energy is 75.52kJ/mol. Finally, the good catalytic activity of Ti-PA was illustrated by comparing it with currently reported catalysts.

Investigation of the performance and emissions of a diesel engine fuelled with bio-oil generated through microwave-assisted pyrolysis of a blend of hazelnut, walnut, and polyethylene terephthalate waste

New and renewable energy sources are the most important issue nowadays. Bio-oil which can replace fossil fuel is an alternative source of energy. In this study, the performance effects and emissions of bio-oil produced by microwave-assisted pyrolysis system (MAP) from the walnut shell (WS), hazelnut shell (HS), and polyethylene terephthalate (PET) waste mixtures on a single-cylinder diesel engine were investigated. For this purpose, WS, HS, and PET wastes were mixed in two different proportions and converted into pyrolytic oil in the MAP system at 700 watts of microwave power and a 30-minute retention time. Produced pyrolytic oils were converted into bio-oil as S1 (46.25% WS + 46.25% HS + 2.5% PET) and S2 (43.75% WS + 43.75% HS + 7.5% PET) through a 3-stage basic upgrading steps. Experimental results showed that MAP of mixed WS, HS, and PET resulted in high hydrocarbon content bio-oil. In the engine experiments, bio-oil was mixed with diesel at 10%, 20%, and 30% ratios by volume and used in a diesel engine at different Brake Mean Effective Pressure (BMEP) (1.4, 2, 2.7, and 3.4 bar). Engine performance has been found to be comparable to diesel at low blend percentages. At 3.4 bar BMEP, while the brake-specific fuel consumption (BSFC) of diesel was 712 g/kWh, it was obtained as 832 and 804 g/kWh at S1 and S2, respectively. However, when the emissions were evaluated in general, it was determined that the emission values increased with increasing bio-oil/diesel blend ratios due to the high viscosity, higher density, and low cetane number of bio-oil compared to diesel.

Oscillation rheology, calorimetry and computed tomography: A practical toolkit combination of qualification for real poly(ethylene terephthalate) waste

The conventional qualification methodologies, such as internal viscosity measurement and Melt Flow Index (MFI) tests, which are routinely applied to pristine materials and homogenous waste, are not directly transferrable to the qualification process of plastic mixtures. The current investigation is oriented towards the development of a pragmatic suite of measurements techniques aimed at facilitating the qualification of diverse real polyethylene terephthalate (PET) waste streams. This is primarily achieved through the integration of oscillatory rheology, calorimetry and computed tomography (CT). Samples derived from both selective income (SI) and sorting residue (SR) of a manual selective waste sorting plant are included, along with an examination of PET material originating from refuse-derived fuel (RDF). To establish references for comparison, manually collected bottles with (BCL) and without (B) caps and labels are employed, leveraging their known composition and purity. Calorimetry reveals that the glass transition temperature (Tg) is the most sensitive parameter for tracking the structural and compositional changes in waste PET-based streams. The utilization of temperature sweep test in rheology for determining the melting temperature (Tm) proves advantageous, offering a significantly shorter measurement time (∼1:24) compared to calorimetry. Importantly, this approach yields the Tm of the genuine composition rather than individual components. Detection of metal content contaminations in PET waste streams is made possible through CT, while frequency tests in rheological measurements demonstrate effectiveness in discerning their effects.

Multi-criteria decision making tool for sustainable concrete production using waste polyethylene terephthalate bottle cap aggregates

The widespread use of concrete has raised concerns about the consumption of its raw materials. To address this issue, researchers are actively exploring alternative waste materials to reduce the environmental impact of the construction industry. With this objective current study aims to investigate potential use of waste polyethylene terephthalate (PET) bottle cap aggregates on the characteristics of concrete, both in its fresh and hardened states. Three variations of modified waste PET aggregates (PETA): full (F), half (H), and quarter (Q), with the aim of evaluating their suitability as replacements for conventional coarse aggregates (CCA) was examined. The research assesses the effects of different PETA proportions (3%, 5%, and 8%) on concrete workability, compressive strength, splitting tensile strength, and flexural strength. The findings reveal that PETA-F and PETA-H adversely affect workability, primarily due to their larger surface area and difficulty in achieving homogeneous blending with other ingredients. In contrast, PETA-Q exhibits superior workability. The use of PETA-Q results in reduced compressive strength due to its smaller size and limited load-bearing capacity. Notably, PETA-H demonstrates improved compressive strength after 28 days. Interestingly, PETA-Q shows enhancements in splitting tensile and flexural strength, making it the top-performing alternative for fresh and hardened concrete properties. Overall, this research indicates that PETA-Q is most suitable for sustainable concrete production. Furthermore, the application of a multi-criteria decision-making tool validates our findings and determines that a 5% replacement of CCA with PETA is optimal, as higher replacements result in strength reduction. The utilization of PETA not only minimizes CCA consumption but also contributes to the development of eco-friendly, sustainable concrete. This study underscores the potential of environmentally conscious concrete and encourages the adoption of sustainable solutions for plastic waste management.

Spent Lithium-Ion Batteries Derived Co3O4 for Electrocatalytic Polyethylene Terephthalate Plastic Recycling.

Spent lithium-ion batteries (LIBs) are an essential secondary resource containing valuable metal elements. Transforming spent LIBs into efficient catalysts through a simple process presents a promising strategy to address both metal resource scarcity and clean energy challenges. Herein, a deep eutectic solvent-assisted synthesis of Co3O4 material from spent LIBs is proposed. The obtained Co3O4 material possesses efficient and stable electrocatalytic activity for converting raw polyethylene terephthalate (PET) bottles into high-purity formic acid and terephthalic acid products under ambient conditions. As expected, the Co3O4 catalyst exhibits a high FE of 92 % with a concentration of produced potassium formate of 23.6 mM under alkaline conditions. This study presents a waste-treating-waste strategy for the simultaneous recovery of spent LIBs and PET waste in a greener manner.

Conversion of Contaminated Post-Consumer Polyethylene Terephthalate into a Thermoset Alkyd Coating Using Biosourced Monomers.

The synthesis of a high-performance oxidative cross-linked thermoset alkyd coating is described that utilizes a novel recycling strategy from contaminated postconsumer waste polyethylene terephthalate (wPET). A single-stage "depolymerization-repolymerization" process has been developed that allows the exploitation of a waste stream from a commercial PET recycling process with 95% efficiency, which, when copolymerized with glycerol and tall oil fatty acid, delivers a sustainable fatty acid-functional polyester suitable for use in thermoset alkyd coatings. Physical drying challenges have been tackled via the development of a convergent polymer formulation strategy from a single source of wPET and the formulation of the resulting fatty acid-functional polymers with commercial alkyd driers, delivering a thermoset alkyd coating suitable for industrial applications.

Unveiling synergy of strain and ligand effects in metallic aerogel for electrocatalytic polyethylene terephthalate upcycling

Recently, there has been a notable surge in interest regarding reclaiming valuable chemicals from waste plastics. However, the energy-intensive conventional thermal catalysis does not align with the concept of sustainable development. Herein, we report a sustainable electrocatalytic approach allowing the selective synthesis of glycolic acid (GA) from waste polyethylene terephthalate (PET) over a Pd67Ag33 alloy catalyst under ambient conditions. Notably, Pd67Ag33 delivers a high mass activity of 9.7 A mgPd-1 for ethylene glycol oxidation reaction (EGOR) and GA Faradaic efficiency of 92.7 %, representing the most active catalyst for selective GA synthesis. In situ experiments and computational simulations uncover that ligand effect induced by Ag incorporation enhances the GA selectivity by facilitating carbonyl intermediates desorption, while the lattice mismatch-triggered tensile strain optimizes the adsorption of *OH species to boost reaction kinetics. This work unveils the synergistic of strain and ligand effect in alloy catalyst and provides guidance for the design of future catalysts for PET upcycling. We further investigate the versatility of Pd67Ag33 catalyst on CO2 reduction reaction (CO2RR) and assemble EGOR//CO2RR integrated electrolyzer, presenting a pioneering demonstration for reforming waste carbon resource (i.e., PET and CO2) into high-value chemicals.

From Polyester Plastics to Diverse Monomers via Low‐Energy Upcycling

AbstractPolyester plastics, constituting over 10% of the total plastic production, are widely used in packaging, fiber, single‐use beverage bottles, etc. However, their current depolymerization processes face challenges such as non‐broad spectrum recyclability, lack of diversified high‐value‐added depolymerization products, and crucially high energy consumption. Herein, an efficient strategy is developed for dismantling the compact structure of polyester plastics to achieve diverse monomer recovery. Polyester plastics undergo swelling and decrystallization with a low depolymerization energy barrier via synergistic effects of polyfluorine/hydrogen bonding, which is further demonstrated via density functional theory calculations. The swelling process is elucidated through scanning electron microscopy analysis. Obvious destruction of the crystalline region is demonstrated through X‐ray crystal diffractometry curves. PET undergoes different aminolysis efficiently, yielding nine corresponding high‐value‐added monomers via low‐energy upcycling. Furthermore, four types of polyester plastics and five types of blended polyester plastics are closed‐loop recycled, affording diverse monomers with exceeding 90% yields. Kilogram‐scale depolymerization of real polyethylene terephthalate (PET) waste plastics is successfully achieved with a 96% yield.

An evaluation of the environmental impact and energy efficiency of producing geopolymer mortar with plastic aggregates

The imperative to mitigate carbon emissions and seek sustainable alternatives to cementitious materials has driven the advancement of geopolymer binders, which are inorganic binders of aluminosilicate industrial-waste materials activated by alkaline agents. The use of geopolymers carries the potential for significant reductions in greenhouse gas emission. Furthermore, the incorporation of plastic waste as aggregates addresses not only resource conservation but also environmental sustainability. This study conducted a comprehensive life-cycle assessment of the use of geopolymers from fly ash as a precursor with polyethylene terephthalate (PET) waste as a substitute for natural aggregates. It was observed that when replacing natural aggregates with PET waste to the maximum extent, the global warming potential (GWP) in the category of emissions related to aggregate preparation increased by 16.7 %. This increase was attributed to significant emissions generated during PET processing, including activities such as washing and grinding. The total GWP to produce one cubic meter of geopolymer mixture was 643.55 kgCO2-e without PET aggregates and 667.86 kgCO2-e with maximum use of PET aggregates. The optimization of energy-intensive PET preparation processes led to a remarkable reduction of 19.63 % for production of geopolymer mixture with maximum use of PET aggregates. These findings show the potential for improved sustainability in the production of geopolymer mixtures and emphasize the critical role of optimizing the production processes in mitigating their environmental impact.

Recycled PET/PA6 Fibers from Waste Textile with Improved Hydrophilicity by In-Situ Reaction-Induced Capacity Enhancement.

Due to the increasing amounts of textile waste, textile to textile recycling is of prime concern. Polyethylene terephthalate (PET) represents the most extensively used type of chemical fiber. Its spinnability suffers from impurities and degradation in the processing, which limits its recycling to new fibers. Here, recycled polyester is blended with a small amount of recycled nylon, and the regenerated fibers, which demonstrated good mechanical properties, were obtained via a melt spinning machine. The mechanical properties, thermal properties, rheological properties, and chemical structure of the modified recycled fibers were investigated. It was found that when compared with rPET-T fibers, the elongation at break of rPET-Ax fibers increased to 17.48%, and the strength at break decreased to 3.79 cN/dtex. The compatibility of PET and PA6 copolymer were enhanced by copolymers produced by in-situ reaction in the processing. Meanwhile, the existence of PA6 increases the crystallization temperature and improves the hydrophilicity of the fibers. This study realized the high-value recycling of waste PET fabric to new fibers, which opens a door for the large utilization of waste textiles.

Manufacturing and characterization of waste polyethylene terephthalate-based functional composites reinforced with organic and inorganic fillers

ABSTRACT Many fillers are employed as reinforcement in polymeric materials to improve their properties and reduce expenses. This research aims to improve the mechanical and thermophysical properties of waste polyethylene terephthalate (WPET). Using recycled materials is also one of the study’s objectives in support of environmental preservation. Glass fiber (3 wt.%, 6 wt.%, 9 wt.%, and 15 wt.%), calcium carbonate (5 wt.%, 15 wt.%, and 25 wt.%), and corn starch (3 wt.%) have all been added to WPET in different ratios to create composite materials. The mechanical strength, Shore D hardness tests, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and thermal, mechanical, physical, and chemical properties of these composites have all been investigated. It has been shown that while the amount of starch in the samples remains constant, the hardness increases as the amount of calcite and glass wool increases. The thermal conductivity does not significantly change as the ratio of glass fiber increases, notwithstanding a modest drop Nonetheless, the thermal conductivity values rise in tandem with the calcium carbonate (CaCO3) ratio.

Synthesis of Sn-based nanocomposites using waste polyethylene terephthalate (PET) for the electrochemical reduction of CO2 to formate

Synthesis of Sn-based nanocomposites using waste polyethylene terephthalate (PET) for the electrochemical reduction of CO2 to formate

Full valorisation of waste PET into dimethyl terephthalate and cyclic arylboronic esters

Developing efficient and cost-effective methodologies for high value-added conversion of waste plastic delivers substantial environmental and economic benefits. Herein, we develop a novel approach utilizing boric acid in the methanolysis of waste polyethylene terephthalate (PET) to derive pure dimethyl terephthalate (DMT) and boronic acid esters through in-situ capture of ethylene glycol (EG). It not only upcycles waste PET but also eliminates intricate EG purification processes. Catalyzed by magnalium-aluminum-layered double oxides (Mg4Al1-LDO), this method achieved 100 % conversions of PET with 96 % and 99 % yields of arylboronic esters and DMT, respectively. Kinetic studies and in-situ Fourier-transform infrared spectroscopy (FT-IR) demonstrated the pivotal role of the monodentate methoxy species, generated through the interaction of medium basic Mg–O ion pairs and methanol. This method demonstrates applicability for the upcycling of assorted discarded PET wastes, polyesters, and polycarbonates with EG units, highlighting its potential as a comprehensive solution for waste plastic management.

Synthesis of Cr(OH)3/ZrO2@Co-based metal-organic framework from waste poly(ethylene terephthalate) for hydrogen production via formic acid dehydrogenation at low temperature

Recycling waste polyethylene terephthalate (PET) bottles into value-added ligand materials for synthesizing metal-organic frameworks derived catalysts is an eco-friendly and economically viable process. The waste PET bottles were readily broken down into 1,4-benzenedicarboxylic acid (BDC) ligands in a highly alkaline environment. Herein, we fabricated a Co@Cr(OH)3/ZrO2 catalyst via the carbonization of PET-derived UiO-66 metal-organic frameworks for the catalytic dehydrogenation of formic acid at low temperatures. The as-prepared Co@Cr(OH)3/ZrO2 NP catalyst provides a turnover frequency (TOF) of 7685 h-1 for hydrogen generation (120 mL in 1.5 min) at ambient temperature. This is due to the uniform dispersion of the fine metal NPs (Co NPs, ∼3.75 nm) and the synergistic effect of the Co NPs and Cr(OH)3/ZrO2 supports. In addition, the characterization results indicate that porous Zr-MOFs may effectively enclose extremely small particles, which is favorable for enhanced dehydrogenation performance. In addition, the Co@Cr(OH)3/ZrO2 catalysts demonstrated excellent stability against aggregation and were recyclable over seven cycles without any significant catalytic loss. Thus, this study provides a sustainable methodology for the development of MOF-derived, effective, and stable catalysts for formic acid (FA) dehydrogenation towards hydrogen production.

Laser-Induced Carbonization of Ni-BDC Layer on PET: Functional Upcycling of Polymer Wastes Towards Bend Resistive Sensor

The growing accumulation of waste polyethylene terephthalate (PET) presents a significant environmental challenge requiring the development of sustainable recycling methods. In this study, a novel approach for upcycling preliminary recycled waste PET into bend resistive sensors through laser-assisted carbonization of surface-grown Ni-BDC (BDC = 1,4-benzenedicarboxylate) has been proposed. The fabrication process involves the solvothermal formation of a homogeneous Ni-BDC layer, followed by treatment with a 405nm laser system to create a graphene-like layer with enhanced conductivity (sheet resistance 6.2 ± 3.4 Ω per square). The developed sensor demonstrates remarkable robustness, a linear response in a wide bending angle range (6 to 44º), as well as excellent mechanical stability and stiffness. This contribution paves the way for the development of high-value materials from waste PET as a resource for applications in the Internet of Things, otherwise discarded materials.

Geopolymer Production From Waste Polyethylene Terephthalate and Glass For Clay Subgrade Stabilization

In this study, the efficacy of Polyethylene Terephthalate (PET) and Waste Glass Powder (WGP) as soil stabilizers was investigated to address the research questions and objectives. It examines the enhancement of mechanical strength of clayey subgrade soils sourced from Ogun state, Nigeria across varying proportions (5% −20%) including the potential cost analysis. Providing experimental insights into soil stabilization using PET individually and in combination with WGP-based geopolymers. Optimal stabilization was achieved at 5% PET, accompanied by 5%-20% WGP, and activated with a 2M NaOH solution. Results demonstrated enhanced mechanical strength with both stabilizers, with the combination of PET and WGP proving the most effective. Specifically, stabilization with 5% PET (1.18mm) WGP geopolymer, activated with 2% NaOH, yielded optimal results, exhibiting UCS values ranging from 180kN/m2 to 320kN/m2, surpassing cement-based stabilization (UCS value: 380kN/m2). Moreover, durability testing revealed significant improvements, with PET+WGP samples displaying a UCS mean of 259.4kN/m2, a weight of 89.67g, and a percent change in mean and weight of −25.79% and −25.86%, respectively, compared to cement-stabilized soil (UCS mean: 408.66 kN/m2, percent change: 2.15%, weight mean: 109.25g, percent change: -25.86%). Furthermore, PET+WGP exhibited a 125% increase in CBR compared to PET alone and a better cost reduction of $6,153,850,000.00 for 100km, highlighting its superior performance and cost reduction. The findings of this study hold significance for informed decision-making in material selection for road pavement works, offering an alternative method and contributing to Sustainable Development Goals and Circular Economy initiatives by advocating sustainable waste management and road infrastructure.

The effect of Polyethylene Terephthalate (PET) plastic addition to AC-WC in a wet mixture on increase of asphalt stability

PET (Polyethylene Terephthalate) plastic is one of the most common types of plastic used in Indonesia. Its existence has contributed significantly to various sectors, including the food and beverage, cosmetic, pharmaceutical, and other consumer product packaging industries. However, the use of PET plastic also creates a number of impacts that need to be considered. PET (Polyethylene Terephthalate) plastic has become an attractive alternative in the construction industry in Indonesia, particularly in its use as an asphalt mixture in road construction. This study aimed to determine the effect of the addition of PET waste to the asphalt on the value of Marshall characteristics as well as the optimum asphalt content and plastic content in the AC - WC mixture. Basic testing of 4 %, 5 %, and 6 % (by weight of asphalt) PET plastic mixture with wet mixing method where PET plastic is put into hot asphalt and stirred until homogeneous. Marshall test data will go through Formality Test, Homogeneity Test, Two-Way ANOVA, Duncan Test, and Correlation Regression Analysis to get the 3D graph equation. The result is that PET plastic affects the asphalt mixture by increasing the stability value and MQ value, for flow, VFB, and VMA values have decreased. VIM value increased at 4 % level and decreased at 6 % level. From the ribbon graph, the optimum asphalt content for each percentage of PET content is obtained, namely 4 % PET KAO value of 6.2 %, 5 % PET KAO 6.25 %, and 6 % KAO 6.28 %. It can be concluded that the mixing of PET with asphalt in AC-WC mixtures can be maximum if the right percentage combination of asphalt and PET content. From the 3D Graphic Method, it results that the maximum use of plastic PET is at a content of 5.40 %, and an asphalt content of 6.35 %, will produce an asphalt stability of 1714.232 kN

Non-contact terahertz evaluation of the melting point for PET bottles

From measurements of the terahertz spectra of commercial polyethylene terephthalate (PET) bottles, a linear correlation is observed between the melting point of the plastic and the absorption intensity around 4 THz. This result indicates that the melting point could be estimated using a non-contact method from the 4 THz peak intensity of the PET bottles. The melting points of the PET bottles used as samples in this study varied from 500 to 503 K. In the present-day recycling process, all waste PET is heated to the same temperature above the highest of the melting points. Based on the data obtained in this study, if could be possible to sense the melting point of waste PET in advance without heating and therefore to optimize the thermal budget of the recycling process.

Application of Infrared Pyrolysis and Chemical Post-Activation in the Conversion of Polyethylene Terephthalate Waste into Porous Carbons for Water Purification.

In this study, we compared the conversion of polyethylene terephthalate (PET) into porous carbons for water purification using pyrolysis and post-activation with KOH. Pyrolysis was conducted at 400-850 °C, followed by KOH activation at 850 °C for samples pyrolyzed at 400, 650, and 850 °C. Both pyrolyzed and post-activated carbons showed high specific surface areas, up to 504.2 and 617.7 m2 g-1, respectively. As the pyrolysis temperature increases, the crystallite size of the graphite phase rises simultaneously with a decrease in specific surface area. This phenomenon significantly influences the final specific surface area values of the activated samples. Despite their relatively high specific surface areas, pyrolyzed PET-derived carbons prove unsuitable as adsorbents for purifying aqueous media from methylene blue dye. A sample pyrolyzed at 650 °C, with a surface area of 504.2 m2 g-1, exhibited a maximum adsorption value of only 20.4 mg g-1. We propose that the pyrolyzed samples have a surface coating of amorphous carbon poor in oxygen groups, impeding the diffusion of dye molecules. Conversely, post-activated samples emerge as promising adsorbents, exhibiting a maximum adsorption capacity of up to 127.7 mg g-1. This suggests their potential for efficient dye removal in water purification applications.

Waste polyethylene terephthalate plastic derived Zn-MOF for high performance supercapacitor application

A simple chemical approach was used to prepare Zn-MOF or MOF-5 derived from polyethylene terephthalate bottles for supercapacitor applications. The morphology, and structure of PET-derived MOFs were characterized using various techniques, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, fourier transform infrared spectroscopy, and BET surface area and nitrogen adsorption/desorption analysis. The BET surface area of MOF-5 was determined to be 88 m2g−1 and N2 adsorption–desorption analysis, showed the type-IV isotherms and suggest the existence of capillary condensation within the meso- and micropore structures. An excellent specific capacitance ranging from 341 to 191 F g−1 recorded form the scan rate of 2–200 mV s−1 by CV for Zn-MOF. Moreover, the highest specific capacitance 353 F g−1 calculated at 0.5 A/g current density. The highest value of specific capacitance Cs 353 F g−1 was found for lowest current density of 0.5 A/g. An excellent cyclic stability was obtained after running 2000 cyclic runs at a scan rate of 50 mV s−1. The small semicircle of EIS plot exhibits superior electrochemical performance of the Zn-MOF. The waste PET plastic derived Zn-MOF showed an excellent supercapacitor performance which can be utilized in energy storage applications. This approach not only facilitates environmental remediation but also offers a valuable organic linker for energy material synthesis.