PET Waste Research Articles

Chemical Degradation of Waste PET and Its Application in Wood Reinforcement and Modification.

In recent years, with the increasing scarcity of fossil resources and the worsening environmental pollution, the effective utilization of wood and plastic waste has become a critical issue. In this paper, propylene glycol (PG) was used as an alcoholysis agent to degrade waste poly(ethylene terephthalate) (PET), and unsaturated polyester (UPR) was synthesized by the polycondensation reaction. The Chinese fir was modified by chemical impregnation to obtain a new type of waste PET-based wood-plastic composites. It exhibits a compressive strength of about 107 MPa and a water absorption of less than 20%. These results highlight the outstanding modification effect on fir, demonstrating excellent mechanical properties and corrosion resistance. This study presents a green and efficient method for the preparation of wood-plastic composites and the recycling of waste PET, providing promising solutions for sustainable resource utilization and environmental protection.

A green synthesis of CuInS2/MIL-101(Cr) nanocomposite with efficient visible light induced photocatalytic activity

This study demonstrates the sustainable synthesis of multifunctional CIS@MIL-101(Cr) composites for water treatment applications. The composites were prepared via hybridization of CuInS2 with MIL-101(Cr) resulting in the formation of CIS nanoplates incorporated into MIL-101(Cr). The composites exhibited enhanced visible light photocatalytic activity due to their low bandgap energy and were tested for tetracycline photodegradation achieving a degradation efficiency of 98.8%. The material showed high stability after four cycles, and the effects of reactive species on photodegradation were investigated. The kinetics and mechanism of the photocatalytic process were studied, and LC-MS analysis was conducted to identify intermediate products. These results demonstrate the potential of using waste PET to create new semiconductors for water pollution control, promoting a circular material pathway.

Advanced Plastic Waste Recycling-The Effect of Clay on the Morphological and Thermal Behavior of Recycled PET/PLA Sustainable Blends.

Bio-based polymers such as poly(lactic acid), PLA, are facing increased use in everyday plastic packaging, imposing challenges in the recycling process of its counterpart polyester poly(ethylene terephthalate), PET. This work presents the exploration of the properties of PET/PLA blends with raw materials obtained from recycled plastics. Several blends were prepared, containing 50 to 90% PET. Moreover, multiscale nanocomposite blends were formed via melt mixing using different amounts and types of nanoclay in order to study their effect on the morphology, surface properties, and thermal stability of the blends. The materials were characterized by X-ray diffraction analysis (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The nanoclay was found to exhibit a uniform dispersion in the polymer matrix, presenting mainly intercalated structures with some exfoliated at low loading and some agglomerates at high loading (i.e., 10%). The addition of nanoclay to PET/PLA matrices increased the roughness of the blends and improved their thermal stability. Thermal degradation of the blends occurs in two steps following those of the individual polymers. Contamination of rPET with rPLA results in materials having poor thermal stability relative to rPET, presenting the onset of thermal degradation at nearly 100 °C lower. Therefore, important information was obtained concerning the recyclability of mixed PET and PLA waste. The perspective is to study the properties and find potential applications of sustainable blends of recycled PET and PLA by also examining the effect of different clays in different loadings. Therefore, useful products could be produced from blends of waste polyester.

Light-Colored rPET Obtained by Nonmetallic TPA-Based Ionic Liquids Efficiently Recycle Waste PET

Light-Colored rPET Obtained by Nonmetallic TPA-Based Ionic Liquids Efficiently Recycle Waste PET

Effect of steel-waste PET hybrid fiber on properties of recycled aggregate concrete based on response surface methodology

To investigate the combined effect of steel and waste PET fibers on the properties of recycled aggregate concrete (RAC), steel-waste PET hybrid fiber reinforced recycled aggregate concretes (HFRACs) were produced. Slump and mechanical strength tests on the samples were performed. The interaction between fiber contents and each performance index was examined by response surface methodology (RSM), and the optimal steel and waste PET fiber contents were obtained by maximizing strength indices simultaneously. The results showed that the contents of two types of fibers had a significant negative impact on workability and positive effect on mechanical strength except the compressive strength which was not significantly affected by the PET fiber content. The slump and compressive strength of HFRAC can be predicted by linear equations with the contents of steel and waste PET fibers, while the splitting tensile strength and flexural strength can be predicted by quadratic polynomial equations. Waste PET fiber properly combined with steel fiber can improve the mechanical properties of RAC, which illustrates steel-waste PET HFRAC has the potential to be green sustainable concrete.

Defective metal–organic framework derived from the waste plastic bottles for rapid and efficient nitroimidazole antibiotics removal

In order to alleviate the pressure on the ecological environment and human health caused by wastewater of nitroimidazole antibiotics and poly(ethylene terephthalate) (PET) plastic waste, we propose a strategy of using defective MIL-68(Al) (d-MIL-68(Al)) derived from waste PET plastic for dimetridazole (DMZ) capture. The resulting d-MIL-68(Al) exhibits an excellent adsorption capacity of 555.6 mg g−1, which is three times of pristine MIL-68(Al) (181.8 mg g−1), demonstrating that the defective structures in d-MIL-68(Al) play a crucial role in the adsorption process. Remarkably, d-MIL-68(Al) can remove nearly 97% of DMZ in the first 10 s, and the removal efficiency reached 99% after adsorption equilibrium, affording a record kinetic rate constant k2 (2.84 g mg−1 min−1). In short, d-MIL-68(Al) possesses both an ultrafast adsorption rate and outstanding adsorption capacity toward DMZ compared with reported adsorbents. Mechanism analysis reveals that the excellent DMZ adsorption performances can be ascribed to the abundant active sites caused by defective structures, as well as the π-π stacking and hydrogen bonding interactions between MOF and DMZ. Hence, d-MIL-68(Al) derived from waste PET plastic is an efficient porous adsorbent for rapid DMZ removal, which not only possesses great potential for wastewater treatment, but also reduces the harmful PET plastic waste, reflecting the concept of sustainable development.

Controlled Glycolysis of Poly(ethylene terephthalate) to Oligomers under Microwave Irradiation Using Antimony(III) Oxide.

We report here the production of higher-order oligomers from the glycolysis of poly(ethylene terephthalate) (PET) by using microwave irradiation in a controlled fashion, instead of its fully glycolyzed product, bis(2-hydroxyethyl)terephthalate (BHET). We show that different catalysts can generate either BHET as the ultimate glycolysis product or higher oligomers of PET under microwave irradiation. Depolymerization of waste PET with an average degree of polymerization (DP) of 417 from water bottles was performed in the presence of 0.25 wt % antimony(III) oxide (Sb2O3) as the catalyst at 240 °C and 400 W microwave power, resulting in an oligomer yield of 96.7% with an average DP of 37. Under these conditions, the conversion of PET to oligomers reached 100% in only 5 min at 240 °C (with a 10 min ramping time) and with a ethylene glycol to PET weight ratio of 2.5. In comparison, under the same reaction conditions, 0.04 wt % of zinc acetate (Zn(OAc)2), a well-known catalyst for PET glycolysis, produces only the BHET monomer in 96.3% yield. Our results demonstrated that by using Sb2O3, the same catalyst that is used extensively for PET synthesis from BHET, under microwave irradiation, the PET glycolysis can be controlled to produce higher PET oligomers as an alternative for a complete chemical depolymerization to the BHET monomer. These oligomers are more suitable for being used as additives for many applications and to produce high-quality second-generation products, including regenerated PET.

Convenient recycling and efficient photocatalytic degradation of disinfection by-products by in-situ growth MOF on PET

Drinking water disinfection processes have made remarkable contributions to keeping drinking water safe. However, these processes can lead to the formation of numerous harmful disinfection by-products (DBPs). Therefore, it is crucial to implement effective measures to minimize the production of DBPs. Herein, PET@PDA@NH2-MIL-53(Fe) (PNM) composite was successfully prepared via surface etching and solvothermal method. The material exhibited excellent photocatalytic activity for DBPs and their precursors at the photo-Fenton system formed by PNM and trace H2O2, which system achieved 99% degradation of 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ) in 30 min, and more than 98% and 95% degradation of phenol and bisphenol A (BPA) in 60 min. The PNM shows more than 90% degradation of DBPs even in real water. Based on free radical trapping experiments, a possible catalytic mechanism was proposed. ·OH and holes were the main active species in the catalytic process. Meanwhile, using UPLC-QTOF and GC–MS to identify intermediate degradation products and Toxtree software to assess toxicity. The PNM maintained a degradation rate over 95% after 5 cycles which demonstrates a remarkable recyclability. This study achieves the reuse of waste PET and opens a new way in exploring the development of eco-friendly photocatalytic materials.

Characterization of Hybrid FRP Composite Produced from Recycled PET and CFRP.

In recent years, carbon fiber has experienced a significant surge in popularity attributed to its exceptional properties, including its high-temperature resistance, mechanical strength, and cost-effectiveness. Many industries have been attracted to the prevalent use of carbon-fiber-reinforced polymers or plastics (CFRP). However, the increasing demand for carbon fiber has created a waste recycling problem that needs to be addressed. This research aimed to develop a recycled composite using PET waste as a solution to the growing demand for both materials. The recycled carbon fibers were processed chemically and mechanically to generate power for this process. Various samples were tested with different proportions of CF (10%, 20%, 30%, and 40%) to analyze their mechanical properties. The recycled composites are examined under tensile test conditions to further explore the waste carbon reinforcement's effect on polymers' characteristics. Scanning electron microscopy was also utilized for mechanical morphology evaluations. After analyzing the data, it was found that samples containing 20% CF had the highest elastic modulus value among all the mixes. This is attributed to the reinforcing effect of the fibers. The Elasticity Modulus of the filaments increased with the concentration of CF, reaching its peak at 20% before decreasing. This trend is also apparent in the visual representations. When compared to recycling, the Elasticity Modulus value of 20% CF filament increased by 97.5%. The precise value for CF with a 20% filament is 4719.3 MPa. Moreover, the composite samples were analyzed using SEM to characterize them, and it was discovered that the incorporation of 20% CF/PET filler produced the composition with the highest strength.

Pemanfaatan Sampah Plastik Pet dan Kertas Sebagai Substitusi Agregat pada Beton Ringan pada Kolom Praktis Bangunan

Almost all building construction projects use concrete as the material. The dead load of a construction building is affected by the specific gravity of the concrete. Lightweight concrete has a unit weight below 1900 kg/m3 (SNI 03-2847-2002). Lightweight concrete uses lightweight aggregate as a constituent, so PET plastic and paper can be used as aggregate substitutes. PET plastic has the characteristics of being durable, strong, light, thick, and with good abrasion resistance, which has a positive effect on the compressive strength test. The paper contains hydrogen, which can bind to OH molecules resulting in a stiff, stable, and strong bond. When the water evaporates, small voids filled with air will form, causing the concrete to become lighter. Based on this, an innovation emerged: the manufacture of lightweight concrete that utilizes PET and paper plastic waste. The study aimed to utilize PET and paper plastic waste as an aggregate substitute for lightweight concrete in practical building columns. This study will use experimental methods with variations in paper waste of 0% and 4% and variations in PET plastic waste of 0% and 0.2%. Cylindrical specimens measuring 15 cm x 30 cm were tested for compressive strength at seven days and 28 days of concrete and absorption at 28 days of concrete. The results of this study are that PET and paper plastic waste can be used as an aggregate substitute for lightweight concrete for practical columns and can achieve concrete compressive strength exceeding the K-125 plan by using SNI 7394:2008 as a reference for Job Mix Design.

A focused review on recycling and hydrolysis techniques of polyethylene terephthalate

AbstractPolyethylene terephthalate (PET) is used in textile and packaging industries. The main source of PET production is fossil fuels with limited capacity. Also, PET products are single use that transform into high volumes of wastes, causing ecosystem problems. Recycling is proposed to confront this challenge. The four major PET recycling techniques are mechanical, chemical, pyrolysis, and enzymatic. Mechanical, pyrolysis, and enzymatic techniques have constrained capabilities to manage PET waste. Chemical recycling is the potential path to expanding recycling PET waste with possibility of upcycling and addressing dirty waste streams. Several chemical methods are introduced and discussed in literature. The five major chemical recycling techniques are glycolysis, alcoholysis, aminolysis, ammonolysis, and hydrolysis. This review describes PET depolymerization via these techniques and introduces hydrolysis as the one that can depolymerize PET in an organic‐free solvent environment. Hydrolysis tolerates PET mixed wastes streams including copolymers. It helps avoid challenges attributed to using organic solvents in reaction systems. Moreover, hydrolysis produces terephthalic acid, PET monomer, which has recently gained attention as the initiative monomer for PET production. The review focuses on three forms of hydrolysis—alkaline, neutral, and acid, by presenting background studies, issued patents, and recent trends on application of hydrolysis.

Mechanically strong and heat-resistant waste poly (ethylene terephthalate) derived by carbon dioxide treatment at ambient temperature

Due to the ever-increasing consumption of poly (ethylene terephthalate) (PET) for the industries of packaging and electronics, the waste non-degradable PET has brought serious ecological pollution. However, the current recovery rate of waste PET is still limited, and the mechanical and heat-resistant properties are too poor to meet the requirements of practical applications. The recycling of waste PET is of practical significance to material/energy saving and environmental protection, contributing to the sustainable development of economy and society. In this work, an innovative method was proposed to fabricate strong and heat-resistant materials by using waste PET bottle flakes via carbon dioxide (CO2) treatment at ambient temperature. The results show that the crystallinity of the PET samples treated by CO2 at 800 psi is increased by 30.6%, the tensile strength and Young's modulus are increased by 21.9% and 20.6%, respectively, compared with untreated samples. Moreover, the dynamic mechanical analysis indicates that the heat-resistant performance of CO2-treated samples is significantly improved, whose storage modulus increased 33.5% and glass transition temperature increased 17.7 °C. Furthermore, aiming to investigate how the CO2-treatment improved the mechanical performance of the waste PET, the sorption-desorption experiments were conducted to examine the sorption kinetics of CO2 in the matrix, combined with the Avrami model employed to analyze the crystallization kinetics of PET under high-pressure CO2. It demonstrates that the enhancement of the tensile strength is ascribed to the transition of crystals from two-dimensional structures to three-dimensional structures with an increment in the CO2 pressure.

On the feasibility of using Polyester (PE) waste particles from metal coating industry as a secondary raw materials in concrete

Reduction of CO2 emissions and plastic waste are the main environmental problems that modern society is dealing with. Concrete industry is continuously investing in research and development aimed at producing sustainable cementitious materials. In the last decades, it has gained interest the possibility of reusing polymer waste (mainly PET or PP) in partial substitution of natural constituents (aggregates) or as fiber reinforcement. As a matter of fact, because of the poor mechanical characteristic of polymers compared to the one of natural aggregates, the final cementitious composite has reduced mechanical performance. In the aforesaid framework, the experimental research reported in this paper aims at verifying the feasibility of a pathway able to use fine polymer particles, in detail a Polyester resin (PE resin) which is a waste product of the coating industry, as a partial replacement of sand and, in case, of binder particles, upon a gamma irradiation process similar to the one used for the sanification of containers in food industry, also their effectiveness in performing as seeds of the cement hydration. Firstly, intrigued by a study performed by MIT researchers (in which exposure of PET waste particles to gamma irradiation has been investigated as a method to improve their mechanical performance), the influence of different gamma irradiation dosages (10 kGy or 100 kGy) on PE resin particles was investigated. However, results led to the conclusion that, even with a mere 5% by volume substitution of Portland Limestone Cement (PLC) in the mix, the process does not significantly improve the mechanical performance of cement-based composites. In a second stage, the non-irradiated particles have been employed as a replacement of the binder and/or of the sand at different volume replacement ratios (10% and 20% respectively) in mortar mix designs formulated from typical Self-Compacting Concrete (SCC) mixes. Finally, once identified the most suitable type and level of replacement as the best compromise between performance maintenance and volume of added particles, the scaling up to the concrete mix-design has been performed and the related performance thoroughly tested. The results have provided limited reduction in mechanical properties, with a 20% by volume level of substitution of cement by PE resin particles, highlighting the possibility of reusing economically viable quantities of PE resins into concrete while still being able to use the material for structural application.

The influence of processing temperature on the mechanical properties of recycled PET fibers

Study towards the recycling of PET waste has arisen in the last decades. One of the most widely used methods was the mechanical recycling process due to its simplicity and low cost of production. In this research, PET waste obtained from the disposable water gallon containers was used to produce recycled PET fibers for textile applications. The PET fibers were prepared using the extrusion technique by varying the processing temperatures, i.e., 200, 210, 220, 230, and 240°C. The diameter, FTIR analysis, XRD analysis, and mechanical properties of the PET fibers at various processing temperatures were studied. The results showed that the optimum processing temperature for preparing recycled PET fibers was 210°C with a diameter of 0.23 mm, a degree of crystallinity of 8.9%, a tensile strength of 70.4 MPa, and an elongation at break of 83.6%. In conclusion, PET waste shows a promising application to be processed as recycled PET fibers for textile applications.

Ionothermal synthesis of activated carbon from waste pet bottles for dye waste water treatment

The production and use of poly-ethylene terephthalate (PET) bottles in packaging have increased significantly. Thus, PET bottles have become a significant plastic waste with environmental problems. Currently, the conventional methods for producing activated carbons (ACs) from waste PET are unsustainable, complex, and unfeasible. As a result, ionothermal synthesis (IS) of waste PET bottles impregnated with choline chloride-urea (CU) deep eutectic solvent (DES) was carried out in order to prepare ACs. The obtained ACs were characterized using XRD, CHNS Elemental analysis and FTIR. The as-prepared ACs were effective as adsorbents for dye adsorption from dye waste water. Specifically, the AC obtained from pristine waste PET bottles (956 mgg−1 at 100 ppm) displayed higher adsorptive capacity compared to the ACs obtained from CU-DES impregnated PET flakes (550mgg−1 at 100ppm). Even though it was expected that the use of CU-DES required no post-synthesis washing or higher temperature treatments might be required to improve the adsorptive capacity of the ACs obtained from IS.This research work established that the synthesis of AC from abundant waste PET bottles using a sustainable and facile method could facilitate its commercial application. Also, this work represents the first attempt to produce activated carbons from PET using low temperature annealing in the presence of limited air, instead of the usual pyrolysis.

Preparation of high‐performance polyurethane elastomers via direct use of alcoholyzed waste PET by high molecular weight polyester diols

AbstractProducts obtained by alcoholysis of waste PET are promising raw materials for the synthesis of polyurethane elastomers (PUEs). Alcoholysis of PET by low molecular weight diols such as ethylene glycol yields low molecular weight products. The latter need to be polymerized to high molecular weight polyols which are subsequently used as soft segments for the synthesis of PUEs. This work aims to look for suitable high molecular weight diols for the alcoholysis of waste PET to yield high molecular weight products which can be directly used as soft segments for the synthesis of PUEs. This approach allows to save the polymerization step for the formation of high molecular weight polyols. Specifically, polyester diols such as polycaprolactone diol (Mn = 2000) were used for the alcoholysis of waste PET. The resulting PUEs exhibited very good mechanical properties: a tensile strength of up to 40.95 MPa, an elongation at break of up to 1219%, and a toughness of up to 237 MJ·m−3, along with good transparency and thermal stability.

Analysis of the use of solid waste in road asphalt coatings: a literature review

The precariousness of Brazilian road pavements, added to the problem of solid waste disposal, highlights the relevance of studies aimed at incorporating these materials into asphalt coatings. This procedure can improve the mechanical properties of pavements, as well as bring savings. In this context, this bibliographic research aimed to analyze the use of solid waste ore, PET and sludge from the Water Treatment Plant (WTP) in asphalt coatings. After selecting two studies that aborted the use of each of the aforementioned residues, a comparative analysis was carried out on the methods employed and results obtained, considering the applicable standardization. Results showed that the incorporation of aggregated iron ore residue promotes good results for light and moderate traffic, in places with temperatures below 60°C. Although it decreases the Resilience Modulus, the incorporation of PET waste into mixtures is still environmentally and economically viable. The use of WTP sludge is quite promising, since the technical requirements are met, especially in the case of tensile strength. In general, the results showed several potentialities of the use of residues in asphalt coatings. Thus, it is important that professionals and regulatory bodies develop more studies to prove and promote this more sustainable practice in engineering.

Orange peel ash coated Fe3O4 nanoparticles as a magnetically retrievable catalyst for glycolysis and methanolysis of PET waste

Chemical recycling of PET offers the process of recovering virgin grade raw materials that can be reprocessed to produce an intact polymeric material or other valuable products. In the current study, we investigate the advantages of exercising biowaste derived orange peel ash (OPA) magnetic nano-catalyst, OPA@Fe3O4 as a green and reusable heterogeneous solid catalyst for glycolytic and methanolytic degradation of PET waste. The composition and physical features of the prepared catalyst were studied and analyzed using various techniques. Under the optimized condition, the catalyst was able to obtain an excellent bis(2-hydroxyethyl) terephthalate (BHET) and dimethyl terephthalate (DMT) yield with 100% PET conversion. Moreover, the catalyst was able to be recycled for ten consecutive runs for both processes without a significant reduction in the yield of the reaction, addressing the possible implementation of the catalyst for industrial purposes.

Process Simulation of Terephthalic Acid Using Neutral Hydrolysis of Polyethylene Terephthalate Bottle Waste Method

To mitigate the environment's unique challenges caused by polyethylene terephthalate [PET] bottle litter and to protect the petroleum feedstock. The chemical recycling technology was used to transform PET into practical items with a sizable and successful industrial application. In order to model the chemical neutral hydrolysis depolymerization process of PET plastic wastes utilizing a continuous stir tank reactor for the synthesis of pure terephthalic acid [TPA] and EG for commercial use, this work used ASPEN PLUS V10. The data for the modeling came from an experimental chemical recycling project employing the neutral hydrolysis process to depolymerize PET bottle trash. PET waste was degraded using excess water [H2 O] and zinc acetate [Zn [Ac]2] as the active catalyst. A mean PET particle size of 127.5 m, 1000 kg/h of PET depolymerized at an H2 O: PET [w/w] ratio of 8:1, 513.15 K temperature, 32.0 bar pressure, and 0.5 h residence time were the reaction's ideal working parameters. Regarding PET, it is a first-order reaction. The reaction yielded 782.72 kg/h of TPA, 292.43 kg/h of EG, and a depolymerization of PET of 90.54%. TPA and EG had selectivity of 0.7280 and 0.2720, respectively. Filtration, distillation, and crystallization techniques were used to separate the mixture of components. The heat from the conveyance, reaction, and separation processes was obtained. This effort increased the yield of TPA, the amount of water removed for reuse, the amount of EG generated, and the amount of processing heat required. The procedures and their operating circumstances can be used to scale up commercial processes in the future.

Biotransformation of ethylene glycol to glycolic acid by Yarrowia lipolytica: a route for poly(ethylene terephthalate) (PET) upcycling.

Biological recycling of PET waste has been extensively investigated recently to tackle plastic waste pollution, and ethylene glycol (EG) is one of the main building blocks recovered from this process. Wild-type Yarrowia lipolytica IMUFRJ 50682 can be used as biocatalyst for this purpose. Herein, we report its ability to perform oxidative biotransformation of EG into glycolic acid (GA): a higher value-added chemical with varied industrial applications. Maximum non-inhibitory concentration assay for EG cytotoxicity revealed that this yeast tolerates high concentrations (up to 2 M). Whole-cell biotransformation assays using resting yeast cells showed GA production uncoupled to cell growth metabolism, and 13 C nuclear magnetic resonance (NMR) analysis confirmed GA production. Moreover, higher agitation speed (450 versus 350 rpm) resulted in a 1.12-fold GA production improvement (from 352 to 429.5 mM) during Y. lipolytica cultivation in bioreactors after 72 h. GA was constantly accumulated in the medium, suggesting that this yeast may also share an incomplete oxidation pathway (i.e., it is not metabolized to carbon dioxide) as seen in acetic acid bacterial group. Additional assays using higher chain-length diols (1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol) revealed that C4 and C6 diols were more cytotoxic, suggesting that they underwent different pathways in the cells. We found that this yeast consumed extensively all these diols, however, 13 C NMR analysis from supernatant identified solely the presence of 4-hydroxybutanoic acid from 1,4-butanediol, along with GA from EG oxidation. Findings reported herein reveal a potential route for PET upcycling to a higher value-added product. This article is protected by copyright. All rights reserved.