Post-consumer Polyethylene Terephthalate Bottles Research Articles

Synthesis of graphene oxide from post-consumer PET bottles by a one-step thermal treatment in air atmosphere for removal of methylene blue

Post-consumer polyethylene terephthalate (PET) bottles are promising raw materials to produce value-added materials. This work uses a simple thermal treatment (TT) in an air atmosphere to transform post-consumer PET (PET-W) into graphene-oxide-like material (GOL). A careful analysis of the thermogravimetric (TGA) curves allowed us to determine the optimal temperature for controlling the oxidative decomposition reactions of PET-W at 412 °C while maximizing the bidimensional character of the products. The products of thermal transformation were characterized by Raman spectroscopy, DRX, FTIR, SEM, EDS, XPS, and BET. The results of the characterization indicate the obtaining of a material (identified here as GOLPET) which is characterized by an ID/IG ratio of 0.61, the presence of oxygenated groups such as CO, C-O-C and phenyls at the interphase, and an elemental composition of ∼83.7 (wt.%) and ∼16.27% of carbon and oxygen (wt.%), respectively. XPS allowed us to determine the formation of assembled aromatic chains (Csp2 = 61.53%) and acyclic chains (Csp3=38.47%). Finally, GOLPET absorption capacity was explored for a commercial application such as removing methylene blue (MB dye); complete elimination of MB (99.6%) in an aqueous solution was demonstrated. Considering the annual generation of plastic waste ∼300 million t, the methodology developed in this research can be envisage as an affordable and innovative alternative to produce GO-like materials.

Development and Performance Analysis of a Mini Twin-Shaft Shredder for Efficient Polyethylene Terephthalate (PET) Bottle Recycling

Polyethylene terephthalate (PET) stands out as the most widely recycled plastic globally. However, in the Philippines, the processes associated with PET recycling, particularly the transportation of PET bottles from collectors and consolidators to processing plants, demand significant time, monetary resources, and effort due to the lack of appropriately sized shredder machines in local junkshops to reduce bulkiness. As a response, this study aimed to design a mini twin-shaft PET bottle shredder. The design took into account the constraints and prerequisites of local junkshop proprietors, municipal and barangay local government units, and non-government organizations.
 The machine was comprised of five essential components: the hopper, shredding chamber, power transmission, prime mover, and frame. Post-consumer PET bottles were employed as test materials for experimentation at different treatment speeds: 30, 40, and 50rpm. The experimental layout followed a completely randomized design (CRD). Performance metrics, including shredding capacity, shredding efficiency, and energy demand, were scrutinized based on shaft speed alterations through analysis of variance testing. Additionally, comparison among means was executed using the least significant difference (LSD) method, with a significance level of 5%.
 Results indicated that the highest shredding input capacity of 34.07 kg/hr was attained at a shaft speed of 50rpm, along with a shredding efficiency of 91.3%. The presence of unshredded materials was identified as the primary cause of device inefficiency, constituting 6.44% of the total test materials input. The energy demand was calculated at 0.132 kW-hr/kg. The resulting product dimensions primarily ranged between 25-50mm. A cost analysis demonstrated that the machine would need to shred a cumulative 6,889kg of PET bottles to reach the breakeven point, given a custom rate of Php7/kg ($0.12/kg). The initial investment cost of Php124,383 ($2,194.71) could be recuperated in a mere 1.91 years, yielding an added net income of Php210,000/yr ($3,705.40/yr) for PET collectors and/or consolidators.

Development of a Lux Meter for the Identification of Liquids in Post-Consumer Polyethylene Terephthalate Bottles for Collection Centers in Mexico

This article aims to enhance technological advancements in the classification of polyethylene terephthalate (PET) bottle plastic, positively impacting sustainable development and providing effective solutions for collection centers (CC) in Mexico. Three experimental designs and machine learning tools for data processing were developed. The experiments considered three factors: bottle size, liquid volume, and bottle labels. The first experiment focused on determining the sensor distance from post-consumer PET bottles. The second experiment aimed to evaluate the sensor’s detection ability with varying liquid levels, while the third experiment assessed its detection capability for bottle labels. A digital lux meter integrated with a microcontroller was developed to monitor illuminance in post-consumer PET bottles containing liquid as they moved through a conveyor belt at an average rate of three bottles per second. The implemented methodology successfully detected liquids inside transparent PET bottles when they contained beverages ranging from 25% to 100% of their capacity. This study highlights the feasibility of implementing an affordable design for identifying bottles with liquids at CC.

Discovery of a polyesterase from Deinococcus maricopensis and comparison to the benchmark LCCICCG suggests high potential for semi-crystalline post-consumer PET degradation

Plastic pollution remains a significant environmental challenge, with conventional waste management strategies proving insufficient in addressing the problem. Enzymatic degradation has emerged as a promising alternative, with LCCICCG, an engineered metagenome-derived cutinase, being the most effective in degrading polyethylene terephthalate (PET), the most commonly produced and discarded polyester. However, more efficient PET-hydrolases are needed for the upscaling of a PET-waste biorefinery. In this regard, the study reports the characterization of a novel, phylogenetically distinct, thermophilic polyesterase from Deinococcus maricopensis (DmPETase) and its comparison to LCCICCG. DmPETase is capable of degrading various synthetic polymers, including PET, polyurethane, as well as four semi-crystalline aliphatic polyesters. DmPETase was found to be comparable to LCCICCG at 50 °C in degrading semi-crystalline sections of post-consumer PET bottles, but it appeared to be less sensitive to crystallinity degree increase. This property makes DmPETase a new template for protein engineering endeavors to create an efficient biocatalyst to be integrated into the bio-recycling process of PET waste, without the need for amorphization of the materials.

Preparation and Characterization of Novel Membrane from Waste Polyethylene terephthalate and Bio-based Polymer

A large amount of post-consumer Polyethylene terephthalate (PET) bottle waste could be recycled for downstream products. In this work, used PET bottles were utilized as a raw material to develop environmentally-friendly ultrafiltration membranes by phase inversion technique. Poly(ethylene-2,5-furandicarboxylate) (PEF), prepared from a sustainable bio-based monomer, 2,5-furandicarboxylic acid (FDCA), was blended into rPET matrix to improve the mechanical properties of the membrane. Ethanol was also used as a non-solvent in a coagulation bath and polyethylene glycol (PEG) with a molecular weight of 400 Da was added as a hydrophilic additive. The effects of PEF and PEG incorporation to waste PET-based membranes have been thoroughly studied. The morphology of obtained membrane was investigated using Scanning Electron Microscopy (SEM). The membrane’s permeation and resistance were tested using a pressure-driven dead-end membrane module. The result revealed that adding PEF increased the roughness of the membrane surface, which lowered the flux recovery ratio and rejection performance. However, the filtration performance and the membrane resistance could be improved by adjusting the content of the PEG additive.

Dihydroxy Polyethylene Additives for Compatibilization and Mechanical Recycling of Polyethylene Terephthalate/Polyethylene Mixed Plastic Waste.

Polymer blend compatibilization is an attractive solution for mechanical recycling of mixed plastic waste because it can result in tough blends. In this work, hydroxy-telechelic polyethylene (HOPEOH) reactive additives were used to compatibilize blends of polyethylene terephthalate (PET) and linear low-density polyethylene (LLDPE). HOPEOH additives were synthesized with molar masses of 1-20 kg/mol by ring-opening metathesis polymerization of cyclooctene followed by catalytic hydrogenation. Melt-compounded blends containing 0.5 wt % HOPEOH displayed reduced dispersed phase LLDPE particle sizes with ductilities comparable to virgin PET and almost seven times greater than neat blends, regardless of additive molar mass. In contrast, analogous blends containing monohydroxy PE additives of comparable molar masses did not result in compatibilization even at 2 wt % loading. The results strongly suggest that both hydroxy ends of HOPEOH undergo transesterification reactions during melt mixing with PET to form predominantly PET-PE-PET triblock copolymers at the interface of the dispersed and matrix phases. We hypothesize that the triblock copolymer compatibilizers localized at the interface form trapped entanglements of the PE midblocks with nearby LLDPE homopolymer chains by a hook-and-clasp mechanism. Finally, HOPEOH compounds were able to efficiently compatibilize blends derived solely from postconsumer PET and PE bottles and film, suggesting their industrial applicability.

Valorization and recycling of packaging belts and post-consumer PET bottles in the manufacture of sand concrete

The valorization of local by-products in the manufacture of a new range of sand concrete and the improvement of their properties, will lead to seek an arrangement between performance and cost in order to achieve a resistant material. Waste recycling affects two very important affect namely the environmental impact and the economic impact. The main objective of our work is to contribute to optimize the formulation of sand concrete as part of the recovery of waste, which is harmful to the environment given its bulky and unattractive nature, it is waste plastic. Most PET bottles become waste after use, causing environmental problems. To solve this problem, a method for recycling PET bottles as fibers to strengthen concrete is proposed. Two types of plastic waste are added to sand concrete; the first concerns the recycling of post-consumer bottles in PET, in the form of polyester fiber supplied by the company RET-PLAST and the second type concerns the packaging belts made of polyethylene terephthalate (PET). The properties in the fresh state (workability and density) and in the hardened state (compressive strength, tensile strength and water absorption) of the various produced concretes are analyzed and compared against their respective controls. From the experimental results, it can be concluded that the reinforcement of the cement matrix with PET fibers with a rate of 1% improves the mechanical properties of sand concrete as well as a remarkable decrease in its water absorption capacity.

Hybrid Coatings of SiO2–Recycled PET Unsaturated Polyester Resin by Sol-Gel Process

Hybrid coatings of SiO2 and recycled unsaturated polyester resin (R-UPR) from recycled polyethylene-terephthalate (PET) were prepared by the sol-gel process on glass substrates. First, SiO2 was synthesized by the sol-gel process using a tetraethyl orthosilicate (TEOS) solution. Next, bis(2-hydroxypropyl-terephthalate) (BHPT) was synthesized from mechanical and chemical recycling (glycolysis) of post-consumer PET bottles in propylene glycol (PG) using ZnA as catalyst, in a Vessel-type reactor (20–200 °C); maleic anhydride (MA) was added and, following the same procedure, the unsaturated polyester (UP) was synthetized, which was cooled to room temperature. Next, styrene (St) and benzoyl-peroxide (PBO)-initiator were added to obtain R–UPR. TEOS (T) and three hybrid solutions were synthesized, with molar ratios of 0:1:0 (T), 1:2:0.25 (H1), 1:1:0.25 (H2), and 1:0:0.25 (H3) for R–UPR:TEOS:3-trimethoxy-(silyl)-propyl-methacrylate (TMSPM), respectively, with which TC, HC1, HC2, and HC3 coatings were elaborated using the immersion technique and polymerized (120 °C for 24 h). The solutions were characterized by FT–IR and TGA, and the coatings by SEM, nanoindentation, AFM, adhesion, and contact angle. The results showed that SiO2 enhanced mechanical (hardness and Young’s modulus) and thermal properties of the R-UPR. The coatings adhered perfectly to the substrate, with thicknesses of micrometer units and a flat surface; in addition, hydrophilicity decreased as SiO2 decreased.

Ignored microplastic sources from plastic bottle recycling

The recovery and recycling of plastic products has increased dramatically in recent years as a strategy to achieve sustainable production and minimization of plastic pollution. However, the release of microplastics during plastic recycling has received little attention. We evaluated the generation and fate of microplastics in three typical facilities which make polyethylene terephthalate (PET) flakes using post-consumer PET bottles as raw material. Microplastics, 0.1– 5.0 mm in size, were detected in production wastewater at concentrations ranging from 23.43 ± 1.04 mg/L to 1836.37 ± 31.73 mg/L, while decreased to (8.13 ± 0.42–83.83 ± 0.93) mg/L in discharge effluent and (52,166 ± 2858–68,866 ± 2500) μg/g in sludge. Interestingly, the profiles of microplastics in samples from production wastewater, effluents, and sludge showed significant differences. Although, in all three compartments, the mass of microplastics increased, and the particle number decreased with increasing particle size. Overall, the removal ratio of total microplastics from the production wastewater was 53.47 ± 4.48% to 99.56 ± 0.02% in mass, and from 90.08 ± 0.82% to 99.56 ± 0.05% in quantity. The loss of microplastics from wastewater resulted in their concentration in sludge. Factors that influence the transfer of microplastics from wastewater to sludge should be identified and utilized to maintain a high level of removal and prevent leakage of these particles into the environment.

Bearing capacity improvement using soil-filled post-consumer PET bottles

This study proposes reusing post-consumer soil-filled PET (polyethylene terephthalate) bottles as a novel soil reinforcing element by conducting a laboratory-scale experimental investigation. The concept is that the polymer bottle walls act to confine the interior soil so that the bed behaves somewhat like a brick-built load spreading zone. The soil-filled bottles were horizontally laid within the soil bed in the desired depth and then the backfilling was performed. The effect of different parameters such as depth of placement, width and height of the soil-filled, bottle-reinforced mattress are studied under static plate load testing. Test results revealed that the bottle-reinforced bed is highly rigid, delivering very high bearing capacities at small soil displacements. Optimum depth of placement, width and height of the bottle-reinforced zone were respectively about 0.03B, 2.17B and 0.57B. An improvement in bearing capacity ratio (BCR) by a factor of ∼3, and up to 80% reduction in soil settlement, were observed. The proposed method of soil reinforcement can be an excellent and relatively economic alternative to conventional geosynthetic reinforcement, as well as delivering geotechnical and environmental advantages.

Depolymerization of post-consumer PET bottles with engineered cutinase 1 fromThermobifida cellulosilytica

The enhanced enzymatic activity and thermal stability of cutinase 1 fromThermobifida cellulosilyticaby enzyme engineering were utilized to achieve efficient degradation of post-consumer polyethylene terephthalate (PET) bottle particles.

Preparation of polyethylene terephthalate/xanthan nanofiltration membranes using recycled bottles for removal of diltiazem from aqueous solution

The massive amount of post-consumer polyethylene terephthalate (PET) bottles highlights the need for increasing their recycling rate. So far, there is no report on using waste PET bottles in preparing membranes for the nanofiltration of aqueous media. The present work demonstrates an environmentally-friendly nanofiltration membrane with high performance prepared by recycled PET bottles. During the membrane fabrication, water and methanol were used as two different coagulation baths, and xanthan gum (XA) was incorporated into the membranes as a hydrophilic additive. The obtained membranes were applied in the nanofiltration of an aqueous solution containing diltiazem. Using similar XA loading, PET/XA membranes prepared in methanol were more hydrophilic and generally performed better in the nanofiltration of diltiazem aqueous solution than the PET/XA membranes obtained in water. Among the membranes prepared in this study, the highest rejection value (97.6%) was achieved using the PET/XA membrane prepared with 0.25 wt% of XA in the methanol coagulation bath.

Making polyurethane raw materials from old bottles

Polyurethanes are exceptionally versatile. The materials, formed by reacting polyols with diisocyanates, can be made into skateboard wheels, rigid structures for cars, memory foam for mattresses, and insulation for refrigerators and buildings. But the nature of polyurethanes—custom blends of molecules bound tightly and often irreversibly with cross-links—makes recycling them a challenge compared with thermoplastics like polyethylene terephthalate (PET) or polypropylene, which can be melted down again. Plastics producers have attempted to boost the sustainability of polyurethanes with greener inputs, such as polyols derived from soybean oil. Huntsman is taking a similar strategy, except in its case it is making polyurethanes more sustainable in a way that helps address the broader plastic waste problem: by using polyols derived from recycled plastics. The company just opened a plant in Taiwan that makes its Terol aromatic polyester polyols from postconsumer PET bottles. The 22,000-metric-ton-per-year plant is its second to use the technology. Huntsman

Post-consumer PET Bottle Recycling: Chemical Dose Optimization

Polyethylene terephthalate (PET) bottles are being used in our daily life and consequently go to the landfills after their use. Additionally, virgin PET resins are produced from nonrenewable resources, such as fossil fuels, whose reserves are depleting continuously. Therefore, to maintain ecological and environmental balances as well as for sustainable development, post-consumer PET (pcrPET) bottles should be recycled. Among many recycling processes, mechanical recycling of pcrPET is attractive due to lower cost involvement. One of the most crucial and important processes of mechanical recycling is hot washing for contaminants removal. Hot washing uses a cleaning solution made of caustic soda (NaOH) and detergent at elevated temperature. In this paper, caustic soda and FORYL LFO (FLO) detergent doses were changed gradually to investigate effective contaminants removal through colorimetric study. Finally, concentration vs. absorbance graphs from colorimetric study suggests that 2% NaOH and 2% FLO detergent is the optimum chemical dose at hot washing for pcrPET recycling.

Eco-friendly Waterborne Alkyd Resin from Polyethylene Terephthalate Waste

This work reports a simple and ecofriendly way of recycling polyethylene terephthalate (PET) waste. PET waste was glycolyzed using trimethylolpropane (TMP) giving tetra-functional glycolyzate, to prepare alkyd resin. 0.25% ZnOAc and the TMP to PET molar ratio of 12:1 at 220 °C produced the best yield of glycolyzate. The obtained glycolyzate was characterized by Fourier transform infrared spectroscopy (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) and further used in the synthesis of alkyd resins. The properties of the prepared alkyd resins including acid value, the pencil hardness, chemical resistance and thermal stability, were investigated. The pencil hardness of the cured resins film is 3H, which is better than the commercial alkyd resin YF-155. Thermogravimetric analysis (TGA) exhibited polymer decomposition occurred above 160 °C. When compared to commercial coatings, Zanthoxylum bungeanum seed oil (ZSO)-based alkyd resin from postconsumer PET bottles has potential for commercial applications, and may even be superior in thermal and chemical resistance.

The usage of novel acrylic-modified water-reducible alkyd resin obtained from post-consumer PET bottles in water-based paint formulation

Glycolysis reactions of waste polyethylene terephthalate (PET) flakes obtained from post-consumer water bottles were carried out at 220–250 °C using diethylene glycol, dipropylene glycol and triethylene glycol, and molar ratios of PET/glycol in the glycolysis reactions were chosen to be 1/3. The obtained glycolysis products were used in the synthesis of medium-oil acrylic-modified water-reducible alkyd resins. Acrylic modification was carried out using methacrylic acid–maleic acid copolymer synthesized in our laboratory. The structure of the acrylic copolymer was investigated with FTIR analysis. Films of the modified alkyd resins were prepared and their physical and chemical surface coating properties were investigated. When surface coating test results were evaluated, it was observed that waste PET had no adverse effect on these properties of acrylic-modified water-reducible alkyd resins. Then, two water-based paints were prepared using PET-based acrylic-modified water-reducible alkyd resin and reference acrylic-modified water-reducible alkyd resin as binder. Wet paint properties and physical/chemical dry film properties of paints were determined. When the physical surface coating test results were evaluated, no difference was observed between the properties of both paints. If we evaluate the results of chemical surface coating properties, the hot water and alkali resistance of waste PET-based paint was considerably higher than the reference resin.

An Oxalate-Bridged Binuclear Iron(III) Ionic Liquid for the Highly Efficient Glycolysis of Polyethylene Terephthalate under Microwave Irradiation.

An oxalate-bridged binuclear iron(III) ionic liquid combined with an imidazolium based cation, (dimim)2 [Fe2 Cl4 (μ-ox)], was synthesized and characterized by a wide range of techniques. This halometallate ionic liquid was active in catalyzing the depolymerization of polyethylene terephthalate (PET) by glycolysis, under conventional and microwave-assisted heating conditions. Both methodologies were very selective towards the production of bis(2-hydroxyethyl)terephthalate (BHET). The employment of microwave heating proved beneficial in terms of time and energy saving when compared to the use of thermal heating. Indeed, dielectric spectroscopy studies revealed that the binuclear iron-containing ionic liquid exhibits an excellent heating response under an electromagnetic field. The catalyst provided quantitative conversions to BHET in the glycolysis of post-consumer PET bottles in only 3 h through microwave heating, as compared to 80 % conversion after 24 h under conventional heating.

Synthesis of Recycled Poly(ethylene terephthalate)/Polyacrylonitrile/Styrene Composite Nanofibers by Electrospinning and Their Mechanical Properties Evaluation

Consumption of polyethylene terephthalate (PET) products has increased dramatically in recent decades, resulting in the generation of a large amount of PET waste. For that reason, is necessary to find a new application of recycled material. In this article, we report the synthesis and characterization of recycled poly (ethylene terephthalate) (RPET) obtained from the chemical recycling of post-consumer PET bottles by glycolysis method and the formation of composites nanofibers RPET/polyacrylonitrile (PAN)/styrene (ST). The RPET synthesis was studied through infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The viscosity and frequency sweep of the polymeric solutions was evaluated. The composites nanofibers were elaborated by the electrospinning technique and characterized by scanning electron microscopy (SEM), FT-IR, TGA/DSC and nanoindentation. The RPET/PAN/ST composite nanofibers present an average diameter of 456 nm and higher thermal stability compared PAN fibers. The mechanical properties such as hardness and elastic modulus were 4.5 and 7.5 times PAN fibers values, respectively.

Behaviour of recycled aggregate concrete beam-column connections in presence of PET fibers at the joint region

In this paper the behavior of reinforced concrete (RC) beam-column connections under cyclic loading was analyzed. The specimens, manufactured in a reduced-scale were made of (a) recycled aggregate concrete (RAC) by replacing 30% of natural coarse aggregate (NCA) with recycled coarse aggregate (RCA) and (b) RAC incorporating Polyethylene terephthalate (PET) fiber i.e., PET fiber-reinforced concrete (PFRC) at the joint region. PET fiber (aspect ratio=25) of 0.5% by weight of concrete used in the PFRC mix was obtained by hand cutting of post-consumer PET bottles. A reference specimen was also prepared using 100% of NCA and subjected to similar loading sequence. Comparing the results the structural behavior under cyclic loading of RAC specimens are quite similar to the reference specimens. Damage tolerance, load resisting capacity, stiffness degradation, ductility, and energy dissipation of the RAC specimens enhanced due to addition of PET fibers at the joint region. PFRC specimens also presented a lower damage indices and higher principal tensile stresses as compared to the RAC specimens. The results obtained gave experimental evidence on the feasibility of RAC for structural use. Using PET fibers as a discrete reinforcement is recommended for improving the seismic performance of RAC specimens.

Biocatalysis as a green route for recycling the recalcitrant plastic polyethylene terephthalate.

Biocatalysis can enable a closed-loop recycling of post-consumer PET waste.