Polyethylene Terephthalate Research Articles

Microplastics in rivers of Gujarat (India) until the Arabian Sea: assessment of the sources, distribution and associated environmental risk.

Microplastics (MPs) have become a notable concern and are released into the environment through the disposal or fragmentation of large plastics. Rivers have been the major pathways for MPs present in the oceans, which significantly affects the marine environment. In the current study, water samples were collected from the upper stream and downstream of Damanganga and Tapi rivers across different sites in the state of Gujarat, India for exploration of MPs contamination. Additionally, samples were also collected from Dumas Beach to detect the presence of MPs. MPs were extracted from the samples through sieving, density separation and wet peroxide oxidation (WPO) techniques which were subsequently analyzed using μ-FTIR, optical microscope, Pyrolysis GCMS (Py-GCMS) and SEM. The concentration of MPs was also quantified from each stretch of Damanganga, Tapi rivers as well as Dumas Beach. Findings revealed that Damanganga showed a higher concentration (3.53 particles/L) of MPs as compared to others. Further, optical microscope and μ-FTIR analysis confirm the presence of MPs like Polypropylene (PP), Polystyrene (PS), Polyethylene terephthalate (PET), Polyethylene (PE) and Polymethyl Methacrylate (PMMA). Pyrolysis products of PP, PS and Polyamide (PA) were detected from Py-GCMS studies. Additionally, SEM images revealed that MPs were subjected to weathering, oxidation and atmospheric deposition over the years. The study additionally confirmed the flux of MPs in both the rivers and beach due to anthropogenic and industrial effects. Risk assessment of MPs was performed using the Pollutant Loading Index (PLI), which indicated that the overall MPs pollution in the studied sites was marginal. Nevertheless, the PLI scores revealed that Damanganga was the most prone to MP pollution among the three study sites.

Upcycling Polyethylene Terephthalate Plastic to C2 Chemicals in Parallel With Nitrate Reduction to Ammonia or Electric Energy Generation

Upcycling Polyethylene Terephthalate Plastic to C2 Chemicals in Parallel With Nitrate Reduction to Ammonia or Electric Energy Generation

Understanding the interaction between selected microplastics and the toxic dye "Congo red" in water.

This study thoroughly investigated the adsorption of Congo Red (CR) dye onto various microplastics (MPs), including high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), polypropylene (PP) and polyethylene terephthalate (PET). Initial adsorption capacities (qe) revealed that HDPE had the highest value (21.90mg/g), followed by PVC (4.2mg/g), LDPE (3.7mg/g), PP (3.1mg/g) and PET (2.8mg/g). Based on these findings, HDPE and PVC were selected for detailed analysis. Adsorption experiments were conducted under controlled conditions: CR concentration of 100mg/L, adsorbent dosage of 2g/L, pH of 5, and temperature of 303K. Isotherm studies indicated that HDPE followed the Freundlich model (R2 - 0.99), while PVC was best described by the Redlich-Peterson model (R2 - 0.97). Kinetic analysis showed that HDPE adhered to the Bangham model (reliable ((R2=0.9267, 0.950, 0.988, and 0.988) R2 values obtained for all the concentrations), highlighting pore-filling mechanisms. The conclusion, supported by FTIR analysis, indicates no significant changes in HDPE's functional groups after the adsorption. In contrast, PVC followed a pseudo-second order kinetic model (reliable R2 values (0.999, 0.765, 0.956, 0.972) obtained for all the concentrations), suggesting chemisorption, confirmed by FTIR changes in the C-Cl bonds. The optimal pH for adsorption was 5 for HDPE and 4 for PVC. Both processes were exothermic with intraparticle and film diffusion identified as rate-limiting steps. Maximum adsorption capacities (qmax) were 110.1mg/g for HDPE and 8.1mg/g for PVC. Desorption experiments were conducted only for HDPE due to PVC's lower adsorption. The highest desorption for HDPE occurred at pH 4 (5.7mg/L) with an adsorbent dosage of 2g/L. This study underscores the dual environmental threat posed by MPs, which not only adsorb organic pollutants like CR but also release them under certain conditions. While this research advances our understanding of MPs as pollutant carriers, future work should focus on their desorption behavior in complex, real-world environments. Further studies on other organic pollutants and microplastic types in real wastewater systems are also recommended.

Study on the Antibacterial Properties and Optical Characteristics of Clear Orthodontic Aligners Coated With Zinc Oxide and Magnesium Oxide Nanoparticles.

This study aimed to evaluate and compare the antibacterial properties and optical characteristics of clear orthodontic aligners coated with zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles. In this experimental laboratory study, polyethylene terephthalate glycol (PETG) aligner samples were coated with nanoparticles of ZnO, MgO and a combination of both (ZnO + MgO). The surface coatings were analysed before and after stability testing using field emission scanning electron microscopy (FESEM). Colour changes and translucency were measured using a spectrophotometer, and the antimicrobial and antibiofilm properties were evaluated against Streptococcus mutans and Lactobacillus species. Statistical analysis was conducted using SPSS, with significance set at p < 0.05. Significant statistical differences were found in the colour changes between the groups (p < 0.001), with the greatest change in MgO-coated aligners (0.94 ± 0.09), followed by ZnO + MgO (0.75 ± 0.05) and ZnO (0.5 ± 0.09). ZnO-coated aligners exhibited the highest translucency (47.6 ± 0.44) compared to MgO (45.07 ± 0.74) and ZnO + MgO (45.76 ± 0.7) (p = 0.002 and p = 0.026, respectively). Nanoparticle-coated aligners showed significantly reduced bacterial growth (p < 0.05). The ZnO + MgO combination demonstrated superior antibacterial effects compared to individual coatings. Nanoparticles remained stable after 24-h agitation in artificial saliva and brushing, maintaining 60%-65% stability. The aligners coated with ZnO nanoparticles exhibited the least colour change and the highest translucency compared to those coated with MgO nanoparticles and the ZnO + MgO combination. The highest antibacterial properties were observed in the aligners coated with a combination of ZnO and MgO nanoparticles.

Upcycling of Organic and Inorganic Waste into MIL-88B(Fe) at Room Temperature for Tetracycline Degradation.

Upcycling organic and inorganic waste into value-added metal-organic frameworks (MOFs) presents a sustainable strategy for mitigating waste pollution and promoting economic viability. However, rapid synthesis of MOF materials derived from actual industrial waste under mild conditions remains challenging. Herein, Fe-MOF MIL-88B(Fe) was successfully fabricated within 1 h at room temperature using galvanizing pickling waste liquid and terephthalic acid derived from waste poly(ethylene terephthalate). The resulting Fe-MOF (s-MIL-88B(Fe)) was employed to activate peroxymonosulfate (PMS) under UV light irradiation, achieving over 87% degradation of tetracycline hydrochloride (TCH) within 15 min. The effects of the reaction parameters on TCH degradation were thoroughly investigated. s-MIL-88B(Fe) demonstrated good stability and reusability, maintaining 96% of the initial activity after five cycles. The system also demonstrated adaptability to various organic pollutants and water matrices. Radicals (SO4-•) and nonradicals (1O2, h+) identified as the key reactive species promoted TCH degradation. The formation mechanism of reactive species and the degradation pathway of TCH are proposed. Toxicity evaluation verified the reduced toxicity after the degradation. This work provides a sustainable approach to upcycling industrial waste into MOF-based materials for efficient environmental remediation under mild conditions.

Superhydrophobic Surface-Enhanced Raman Spectroscopy (SERS) Substrates for Sensitive Detection of Trace Nanoplastics in Water.

Nanoplastics, emerging as pervasive environmental pollutants, pose significant threats to ecosystems and human health due to their small size and potential toxicity. However, detecting trace levels of nanoplastics remains challenging because of limitations in the current analytical methods. Herein, we propose a method that combines superhydrophobic enrichment with SERS analysis for detecting trace nanoplastics in aqueous environments. Superhydrophobic SERS substrates were prepared by using a liquid-liquid self-assembly method. The superhydrophobicity facilitated analyte enrichment, and monolayer Au nanoparticles (AuNPs) enhanced the Raman signals. The detection limit for Raman probe crystal violet (CV) using this substrate reached nanomolar (10-9 M), with an RSD of 9.96% across a 40 × 40 μm2 area (441 spots), demonstrating excellent sensitivity and reproducibility. This method successfully detected polystyrene (PS) plastics ranging from 30 to 1000 nm in water with concentrations as low as 0.03 μg/mL. Additionally, nanoscale polyethylene terephthalate (PET) particles were detected in bottled water samples. This approach offers a promising platform for analyzing trace nanoplastics in environmental water samples and addresses the needs of environmental monitoring.

Electrooxidation of Ethylene Glycol to Glycolic Acid with Pt-Ni(OH)2 Catalysts: High Efficiency and Selectivity for PET Plastics Upgrading.

The electroconversion of polyethylene terephthalate (PET) into C2 fine chemicals and hydrogen (H2) presents a promising solution for advancing the circular plastics economy. In this study, we report the electrooxidation of ethylene glycol (EG) to glycolic acid (GA) using a Pt-Ni(OH)2 catalyst, achieving a high Faraday efficiency (>90%) even at high current densities (250 mA cm-2 at 0.8 V vs. RHE). Notably, this catalyst outperforms most existing Pt-based catalysts in terms of catalytic activity. Experimental analyses reveal that: 1) Ni(OH)2 enhances the adsorption of OH- ions and promotes the rapid generation of *OH active species, which are essential for the efficient oxidation of EG to GA; 2) the oxygenophilic nature of Pt improves EG adsorption, and in synergy with Ni, accelerates the oxidation process. Furthermore, Pt lowers the electrolysis potential, preventing excessive oxidation and ensuring high selectivity for GA. This work offers a promising pathway for the electrooxidation-based upgrading of PET plastics and provides valuable insights for future research in this area.

Deep eutectic solvent-assisted recycling of spent lithium-ion batteries into electrocatalysts for polyethylene terephthalate upcycling.

We propose an effective method for selectively extracting the valuable metals from the spent LiNixCoyMn1-x-yO2 cathode material using an oxalic acid-based deep eutectic solvent. Through regulation of the coordination environment, NiO, Co3O4, and Mn3O4 are stepwise separated and further applied in the electrochemical conversion of raw PET bottles to high-purity formic acid.

Evaluating cutinase from Fusarium oxysporum as a biocatalyst for the degradation of nine synthetic polymer

Plastic poses a significant environmental impact due to its chemical resilience, leading to prolonged and degradation times and resulting in widespread adverse effects on global flora and fauna. Cutinases are essential enzymes in the biodegradation process of synthetic polymers like polyethylene terephthalate (PET), which recognized organisms can break down. Here, we used molecular dynamics and binding free energy calculations to explore the interaction of nine synthetic polymers, including PET, with Cutinase from Fusarium oxysporum (FoCut). According to our findings, the polymers poly(ethylene terephthalate) (PET), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(ε-caprolactone) (PCL) can bind to the Cutinase enzyme from F. oxysporum, indicating potential biodegradation activity for these polymers. PET exhibited the highest binding affinity (− 34.26 kcal/mol). Besides PET, the polymers PHBH, PBS, PBAT, and PCL also demonstrated significant affinities for the FoCut enzyme, with binding values of − 18.44, − 29.71, − 22.78, and − 22.26 kcal/mol, respectively. Additionally, analysis of the phylogenetic tree of cutinases produced by different organisms demonstrated that even though the organisms belong to different kingdoms, the cutinase from F. oxysporum (FoCut) showed biological similarity in its activity in degrading polymers with the cutinase enzyme from the bacterium Kineococcus radiotolerans and the fungus Moniliophthora roreri. Furthermore, the phylogenetic analysis demonstrated that the PETase enzyme has a very high similarity with the bacterial cutinase enzyme than with the fungal cutinase, therefore demonstrating that the PETase enzyme from Ideonella sakaiensis can easily be a modified bacterial cutinase enzyme that created a unique feature in biodegrading only the pet polymer through an evolutionary process due to its environment and its biochemical need for carbon. Our data demonstrate that bacterial cutinase enzymes have the same common ancestor as the PETase enzyme. Therefore, cutinases and PETase are interconnected through their biological similarity in biodegrading polymers. We demonstrated that important conserved regions, such as the Ser-Asp-His catalytic triad, exist in the enzyme’s catalytic site and that all Cut enzymes from different organisms have the same region to couple with the polymer structures.

Mechanically Resilient and Highly Efficient Flexible Perovskite Solar Cells with Octylammonium Acetate for Surface Adhesion and Stress Relief.

Flexible perovskite solar cells (FPSCs) have advanced significantly because of their excellent power-per-weight performance and affordable manufacturing costs. The unsatisfactory efficiency and mechanical stability of FPSCs are bottleneck challenges that limit their application. Here, we explore the use of octylammonium acetate (OAAc) with a long, intrinsic, flexible molecular chain on perovskite films for surface adhesion and mechanical releasing. The results showed that OAAc with high structural flexibility and strong molecular interactions can act as a mechanical release layer in releasing residual tensile stress, confirmed by the film and device characterizations as well as finite-element simulation. Moreover, the passivation of the OAAc could increase the formation energy of defects including I vacancy, Pb vacancy, and Pb-I antisite. The experimental results showed that the trap states of perovskites were significantly suppressed after OAAc modification, which is beneficial to the construction of high-quality films. With a high open-circuit voltage of 1.196 V, the efficiency of the OAAc-treated devices increased from 23.14% to 25.47% on a rigid substrate (23.12% on a flexible substrate), yielding superior long-term and mechanical durability. The corresponding flexible device retains 74% of the initial value even after 8000 bending cycles at a bending radius of 5 mm.

High-k organic-inorganic hybrid dielectric material for flexible thin-film transistors and printed logic circuits.

A new photopolymerizable organic-inorganic (O-I) hybrid sol-gel material, AUP@SiOx-184, has been synthesized and utilized as a gate dielectric in flexible organic thin-film transistors (OTFTs). The previously reported three-arm alkoxy-functionalized silane amphiphilic polymer has yielded stable O-I hybrid materials comprising uniformly dispersed nanoparticles in the sol state. In this study, a photosensitizer was introduced, facilitating curing effects under ultraviolet light. Photo-crosslinking enhances the stability of hydroxyl radicals within inorganic nanoparticles, thereby minimizing device hysteresis. This approach also contributes to achieving a low leakage current and a high dielectric constant (high-k) while maintaining reduced thickness. Moreover, AUP@SiOx-184 films are amenable to patterning through UV photopolymerization and can be successfully produced using printing techniques. Compared to other materials, they exhibit outstanding flexibility and improved insulating capabilities. Additionally, OTFTs incorporating AUP@SiOx-184 layers demonstrate extremely stable driving features on flexible substrates. Selective printing and specific patterning play crucial roles in the fabrication of logic circuits. This synthesis strategy has resulted in integrated logic devices that have successfully demonstrated their functionality, highlighting its value for producing functional O-I hybrid materials. Utilizing AUP@SiOx-184 as a gate dielectric in OTFTs showcases its potential to advance electronic technologies that are both flexible and high-performing.

Enantioselective Heck/Tsuji−Trost reaction of flexible vinylic halides with 1,3-dienes

The enantioselective domino Heck/cross-coupling has emerged as a powerful tool in modern chemical synthesis for decades. Despite significant progress in relative rigid skeleton substrates, the implementation of asymmetric Heck/cross-coupling cascades of highly flexible haloalkene substrates remains a challenging and and long-standing goal. Here we report an efficient asymmetric domino Heck/Tsuji−Trost reaction of highly flexible vinylic halides with 1,3-dienes enabled by palladium catalysis. Specifically, the Heck insertion as stereodetermining step to form ƞ3 allyl palladium complex and in situ trapping with nucleophiles enable efficient Heck/etherification in a formal (4 + 2) cycloaddition manner. Engineering the Sadphos bearing androgynous non-C2-symmetric chiral sulfinamide phosphine ligands are vital component in achieving excellent catalytic reactivity and enantioselectivity. This strategy offers a general, modular and divergent platform for rapidly upgrading feedstock flexible vinylic halides and dienes to various value-added molecules and is expected to inspire the development of other challenging enantioselective domino Heck/cross-couplings.

Neutral hydrolysis of poly(ethylene terephthalate) catalysed by highly active terephthalate-based ionic liquids at low loadings.

Novel ionic liquid catalysts comprising terephthalate anions are capable of promoting the neutral hydrolysis of relatively large flake sizes of poly(ethylene terephthalate) at 0.5 mol% loading (200 °C, 4 h, 94% yield) without either attendant product inhibition or product contamination by protonated catalyst. Catalysts with large, lipophilic phosphonium cations outperform more polar variants.

From biofilms to biocatalysts: Innovations in plastic biodegradation for environmental sustainability.

The increase in plastic waste has evolved into a severe environmental crisis, which requires innovative recycling technologies to repurpose used plastic with adequate environmental protection. This review highlights the urgent need for innovative approaches to the treatment and degradation of post-use plastics. It investigates the promising role of biofilms in the biodegradation of polymers, especially for polymers such as polyethylene terephthalate (PET), polyurethane (PU), and polyethylene (PE). By examining biofilms, researchers can determine key enzymes involved in polymer degradation and improve their efficiency through genetic engineering. In addition, the review explores in detail the structure and development of biofilms on polymeric surfaces, elucidating the role of specific microbial strains necessary for biofilm formation and maintenance. Techniques for identifying enzymes within biofilms and improving their degradation ability are also discussed. The review concludes with recent discoveries in enzyme isolation and the key role of biofilms in the degradation and recycling of major plastic pollutants such as PET, PU, and PE. These findings highlight the potential of biofilm-derived enzymes to promote sustainable polymer recycling.

High-throughput screening strategies for plastic-depolymerizing enzymes.

A multitude of plastic-depolymerizing microorganisms and enzymes have been discovered in the plastisphere. Identifying and engineering such microbial strains and enzymes necessitate robust and high-throughput screening strategies for developing effective microbial solutions to counter the plastic accumulation problem and decouple the reliance on fossil resources. This review covers new methods and approaches for the effective high-throughput screening of depolymerizing enzymes for various plastics, such as polyethylene terephthalate (PET), polyurethane (PU), and polylactic acid (PLA). We discuss the application scope of the existing methods, as well as potential developments and integration of screening techniques to identify and enhance plastic depolymerases. The prospects for screening a wider range of plastic depolymerases with the advances in biotechnology tools such as droplet microfluidics and biosensors are highlighted.

Mineral Filler Hybridization in Recycled Polyethylene Terephthalate

Mineral Filler Hybridization in Recycled Polyethylene Terephthalate

Antimicrobial Activity of UV-Activated and Cysteamine-Grafted Polymer Foils Against Bacteria and Algae.

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino and thiol functional groups by cysteamine grafting. X-ray photoelectron spectroscopy (XPS) confirmed increased nitrogen and sulfur content on the modified surfaces. SEM analysis revealed that UV activation and cysteamine grafting resulted in distinct surface roughness and texturing, which are expected to enhance microbial interactions. Antimicrobial tests showed increased resistance to algal growth (inhibition test) and bacterial colonization (drop plate method), with significant improvement observed for polyethylene terephthalate (PET) and polyetheretherketone (PEEK) foils. The important factors influencing the efficacy included UV exposure time and cysteamine concentration, with longer exposure and higher concentrations leading to bacterial reduction of up to 45.7% for Escherichia coli and 55.6% for Staphylococcus epidermidis. These findings highlight the potential of combining UV activation and cysteamine grafting as an effective method for developing polymeric materials with enhanced antimicrobial function, offering applications in industries such as healthcare and packaging.

A study on the compressive strength of three-dimensional direct printing aligner material for specific designing of clear aligners

BackgroundThe demand for orthodontic treatment using clear aligners has been gradually increasing because of their superior esthetics compared with conventional fixed orthodontic therapy. This study aimed to evaluate and compare the compressive strength of three-dimensional direct printing aligners (3DPA) with that of conventional thermo-forming aligners (TFA) to determine their clinical applicability. In the experimental group, the 3DPA material TC-85 (TC-85 full) was used to create angular protrusions called rectangular pressure areas (RPA). A protrusion akin to the power ridge typically employed in conventional TFAs was created using glycol-modified polyethylene terephthalate (PETG; Control 1). RPA was created using the same TC-85 without filling the protrusions (TC-85 blank; Control 2). Compression cycle tests were conducted on an LTM 3 h electrodynamic testing machine (Zwick Roell, Germany), with 500 cycles and compression depths of 100, 300, 500, and 700 µm. Twenty specimens were tested for PETG, 17 for the TC-85 blank, and 19 for the TC-85 full.ResultsChanges in the compressive force were assessed based on the material and thickness. The results indicated significantly higher and broader ranges of compressive strength for specimens fabricated with the 3DPA material TC-85 compared with those fabricated using PETG. Among the TC-85 specimens, TC-85 full demonstrated the highest statistically significant compressive strength .Conclusions3DPA technology enables precise modifications in the shape and inner thickness at specific dental sites, including the creation of ridges in targeted areas, of aligners. These alterations enhance the biomechanical capability of aligners to exert selective forces necessary for desired tooth movement while reducing the number of attachments, thereby demonstrating the clinical potential of 3D-printed aligners in orthodontic treatment.

Adsorption behavior of Cu(II) on UV-aged polyethylene terephthalate and polypropylene microplastics in aqueous solution.

Plastics are widely used across various applications from packing to commercial products. Once discarded, they were subjected to environmental stresses, causing them to degrade into microplastics (MPs). These small, invisible pollutants pose a significant threat to aquatic ecosystems, gradually compromising the resilience and vitality of the natural environment. Moreover, MPs will act as carriers for other contaminants, for example, heavy metals (HMs). Although many studies have explored MPs and HMs independently, their combined behavior and interactions remain poorly understood. Understanding these interactions is increasingly important given rising pollution levels. MP formation and adsorption behavior are heavily influenced by factors such as UV aging, which remains unclear. In this study, both virgin and UV-aged MPs specifically PET and PP (the most widely used plastics globally) were examined in their interactions with copper (Cu2+) solutions. Surface analysis techniques such as FTIR, SEM, XRD, and AAS were employed to compare the virgin and UV-aged MPs. The results revealed that UV-aged MPs exhibited high adsorption capacities for HMs compared to virgin MPs, which can be attributed to increased pore volume and oxidative degradation. Adsorption capacity differences at various concentrations showed up to a 20% increase, with UV-aged PET MPs displaying capacities ranging from 0.6 to 3.54 mg/g. Similarly, UV-aged PP MPs showed a 15% increase in adsorption capacity ranging from 1.51 to 4.25 mg/g. The present study provided the significant evidence on the behavior of MPs adsorption and underscores the need for further research on the long-term environmental impacts of aged MPs and their interactions with pollutants.

Multi-gate neuron-like transistors based on ensembles of aligned nanowires on flexible substrates

The intriguing way the receptors in biological skin encode the tactile data has inspired the development of electronic skins (e-skin) with brain-inspired or neuromorphic computing. Starting with local (near sensor) data processing, there is an inherent mechanism in play that helps to scale down the data. This is particularly attractive when one considers the huge data produced by large number of sensors expected in a large area e-skin such as the whole-body skin of a robot. This underlines the need for biological skin like processing in the e-skin. Herein, we present multi-gate field-effect transistors (v-FET) having capacitively coupled floating gate (FG) to mimic some of the neural functions. The v-FETs are obtained by deterministic assembly of ZnO nanowires on a flexible substrate using contactless dielectrophoresis method, followed metallization using conventional microfabrication steps. The spatial summation of two presynaptic inputs (applied at multiple control gates) of the transistor confirm their neuron-like response. The temporal summation (such as paired-pulse facilitation) by presented v-FETs further confirm their neuron-like mimicking with one presynaptic input. The temporal and spatial summation functions, demonstrated by the v-FET presented here, could open interesting new avenues for development of neuromorphic electronic skin (v-skin) with possibility of biological-skin like distributed computing.