Polyethylene Terephthalate Research Articles

Waste Polyethylene Terephthalate (PET) as a Partial Replacement of Aggregates in Sustainable Concrete

Concrete use is enhanced daily due to infrastructure development, but it has adverse impacts on the environment. Modern lifestyles have led to the increased use of plastic, and, for households, polyethylene terephthalate (PET) plastics are used. However, PET is non-biodegradable and causes adverse impacts on the environment and marine health. So, there is a need to minimize the amount of plastic waste by finding an alternative use for the waste. Our study focuses on creating sustainable concrete by utilizing PET-based plastic waste as a partial substitution for aggregates, aiming to use this concrete for various low-load-bearing construction applications. From our phase analysis study, no adverse effects were found on cement phase formation. We also found that up to 10 wt.% PET incorporation leads to acceptable compressive strength reduction as per ASTM guidelines. To enhance adhesion, the PET was roughened, and, from FESEM, we found effective adhesion of PET waste into the cement matrix. We believe that this sustainable concrete will not only contribute to waste reduction but also promote eco-friendly construction material development.

Microplastic accumulation in one-year freshwater ice: A four-year monitoring study reveals winter dynamics of microplastics

Microplastic research has reached a point where microplastics (MPs) have been found in virtually every environment studied. However, MP studies of freshwater ice are scarce, and the winter dynamics of MPs are less understood. Measuring MPs from one-year freshwater ice samples can aid understanding seasonal MP fluxes in freshwater systems. In this study we explored the same four sites close to urban/suburban areas over four subsequent years. We collected a total of 48 ice samples across all the years and sites with an average sample volume of 2.9 to 5.0 L of liquid water. In addition, we sampled an annually laminated section of bottom sediments representing these four years in seasonal resolution. MP concentrations varied considerably between years and samples, being 1–44 MPs/L in all the ice samples. The MPs found in ice were small with a mean (± average) size of 142 ± 177 μm. In total, 9 different polymer types were identified: the most common types being polypropylene, polyethylene and polyethylene terephthalate. We found that MPs accumulate to one-year freshwater ice, because the MP concentrations found from ice are one to two orders of magnitude higher than concentrations from surfaces waters in the same area. This further confirms that ice acts as a temporal repository for MPs in the aquatic freshwater systems. Our study also indicates that the properties of MPs were relatively similar in all sites around the city. The accumulation of MPs in sediments was highest during the spring flood periods, when MPs were released from the ice and snow at the catchment area of the sediment samples. We highlight the importance of monitoring to collect representative MP data from various environmental compartments.

Seasonal Abundance and Types of Microplastics in Surface Waters of River Sabaki Estuary, Kenya

Increased demand for plastics has resulted in the generation of plastic waste, which poses a threat to the environment in general, and ultimately the marine environment. Estuaries and deltas are the main filters of marine ecosystem pollutants from inland sources. There have been limited studies on temporal variations in microplastic (MP) pollutants in tropical estuaries of Africa. In 2022, a twelve-month sampling survey study was conducted at Sabaki river estuary, in Kenya. A bucket was used to collect water samples, that were sieved through a 225μm sieve. A stereo microscope was used to identify microplastics and their polymer confirmed using FTIR spectroscopy. Data analysis on seasonal difference in abundance of microplastics in surface waters was performed using Minitab software at α ≤ 0.05. The results indicated that the April-June (A-J) long rains season had significantly (P ≤ 0.05) higher levels of MPs due to rainfall runoff, compared to other seasons, namely January –March (J-M), July-October (J-O) and November –December (N-D). The (J-M), (J-O) and (N-D) seasons had similar levels of MPs, which were lower compared to those observed during (A-J) long rains season by 44.3%, 54% and 25% respectively, compared to the highest concentration of 264 MPs m-3 observed during the A-J season. Fragments type of MPs were higher during the wet season, while fiber type of MPs dominated during the dry season. Film and form type of MPs were least abundant. Seasons significantly (P ≤ 0.05) influenced distribution of the different sizes of MPs. Small and medium sized category of MPs occurred and dominated during the dry season, while larger particles dominated during the wet season. Seven (7) differently colored MPs were observed during the study. White colored MPs were most prevalent (33%), followed by blue (23%), black (17%), brown (12%), yellow (5%), red (5%), and green (4%). Five types of plastic polymers were found in surface waters of river Sabaki estuary, namely polyethylene (PE), polypropylene (PP), polystyrene (PS), Polyethylene terephthalate (PET), and Acrylonitrile-butadiene-styrene (ABS).

Accumulation of Microplastics and Potentially Toxic Elements in Plant Leaves Along an Urbanization Gradient in Bangladesh

Potentially toxic elements (PTEs) and microplastics (MPs) in the atmosphere raise widespread apprehension due to their association with the ecosystem and public health. The accumulation of airborne MPs and PTEs was analyzed in Polyalthia longifolia leaves, and the Pollution Index (PI) was calculated along an industrial, residential, and rural gradient in Bangladesh. Only polyethylene terephthalate (PET) was found in the highest concentration in industrial areas compared to other areas. In leaves, a significantly higher Cd, Pb, and Zn concentration was found in industrial regions compared to residential and rural areas. For Cd, the PI was observed to be higher than 1 in rural areas, indicating a moderate level of pollution; it was higher than 3 in residential areas, showing considerable pollution; and it was found to be more than 6 in industrial areas. The higher concentration of both MPs and PTEs with increasing urbanization reflects the influence of anthropogenic activities. The findings of the study demonstrate the fascinating potential of P. longifolia tree leaves as a promising bioindicator for air quality biomonitoring.

Presence of Microplastics in Water, Soil, Organic Fertilizer, and Potato Plants on Potato Plantations

ABSTRACTMicroplastics (MPs) have become a significant environmental concern, but data on their presence in potato gardens are limited. This study aims to identify and quantify MPs in soil, organic fertilizer, irrigation water, and potato plants in potato gardens. Soil, fertilizer, irrigation water, and potato samples were collected from potato fields. Analysis was carried out using a microscope and Fourier transform infrared spectroscopy (FTIR) to identify the shape, color, quantity, and type of MP polymer. The results indicate significant MPs contamination with the most dominant shape of fibers (86%) and fragments (8%), dominant color black (35%) and blue (27%), abundances of MPs 0.10–9.20 g−1, as well as the presence of polyethylene terephthalate (PET) and high‐density polyethylene (HDPE) polymers. These MPs have the potential to harm plant growth and soil quality. MPs are found in significant quantities in potato gardens and have the potential to disrupt agricultural ecosystems. The presence of MPs in potato gardens can affect the quality of agricultural products and human health throughout the food chain.

Modification of Track-Etched Polyethylene Terephthalate Membranes with Functionalized Silanes for Immobilizing Silver Nanoparticles

The present study is dedicated to obtain hybrid polyethylene terephthalate track membranes. For this purpose, the modification of track-etched membranes was performed with 3-aminopropyltriethoxysilane and 3-mercaptopropyltriethoxysilane using additional cross-linking groups based on hydrated forms of aluminum salts and silver nanoparticles were immobilised. The resulting track membranes were studied using energy-dispersive X-ray spectroscopy. Zeta-potential of samples’ surface on each modification step was determined. The presence of silver nanoparticles on track membranes surface was confirmed by scanning and transmission electron microscopy, UV-Vis spectroscopy, and surface-enhanced Raman scattering using 4-aminothiophenol. The proposed approach allows to create surfaces to concentrate selectively compounds with further detection by surface-enhanced Raman scattering.

Advancing protein display on bacterial spores through an extensive survey of coat components.

The profound stability of bacterial spores makes them a promising platform for biotechnological applications like biocatalysis, bioremediation, drug delivery, etc. However, though the Bacillus subtilis spore is composed of >40 proteins, only ∼12 have been explored as fusion carriers for protein display. Here, we assessed the suitability of 33 spore proteins (SPs) as enzyme display carriers by direct allele tagging at native genomic loci. Of the 33 SP investigated, 26 formed functional fusions with β-glucuronidase (GUS) - a ∼272 kDa homotetramer. This almost triples the number of SPs assessed for enzyme display and doubles the number of functional fusions documented in the literature. We quantitatively assessed the 1) SP promoter activation dynamics during growth, 2) supported GUS activity on spores, 3) surface availability, 4) protection from thermal and proteolytic degradation, and 5) compatibility of co-expression of many of these fusions. Multi-copy expression and pairwise co-expression of the most promising SP-GUS fusions highlighted the complexity of spore structure/assembly and difficulty in predicting compatibility between different SPs fusions. We also assessed the suitability of engineered spores to degrade PET (polyethylene terephthalate) films and found that surface exposed SPs were most effective. Beyond the broad survey, a key outcome of our work was the identification of SscA ( s mall s pore c oat assembly protein A ) as an effective spore display carrier. SscA supported enzyme activity at least fourfold higher than any other SP, including the well-established and popular anchor, CotY. We attribute this to the biochemical and genetic features of SscA; its promoter demonstrated early and sustained activation relative to other SPs and its small size (∼3 KDa) likely minimally interferes with enzyme folding, oligomerization, and activity. Although the specific localization of SscA within the spore coat has not been established, its hydrophobic nature and low surface availability suggests that it assembles internally within the spore coat, which makes it highly stabilizing and suitable for many biocatalytic applications. Overall, this work serves as a knowledgebase to advance the biotechnological utility of B. subtilis spores.

All-Printed Microfluidic–Electrochemical Devices for Glucose Detection

Free-standing capillary microfluidic channels were directly printed over printed electrodes using a particle/polymer mixture to fabricate microfluidic–electrochemical devices on polyethylene terephthalate (PET) films. Printed devices with no electrode modification were demonstrated to have the lowest limit of detection (LOD) of 7 μM for sensing glucose. The study shows that both a low polymer concentration in the mixture for printing the microfluidic channels and surface modification of the printed microfluidic channels using 3-aminopropyltrimethoxysilane can substantially boost the device’s performance. It also shows that both device structure and enzyme doping level of the devices play an important role in ensuring the best performance of the devices under various testing conditions.

Pendant Hydroxy Polyethylene Reactive Additives for Improved Mechanical Properties and Melt Processability of Poly(ethylene terephthalate)/Polyethylene Blends

Pendant Hydroxy Polyethylene Reactive Additives for Improved Mechanical Properties and Melt Processability of Poly(ethylene terephthalate)/Polyethylene Blends

Synergetic pyrolysis of lithium-ion battery cathodes with polyethylene terephthalate for efficient metal recovery and battery regeneration

Spent LiNixCoyMnzO2 (x + y + z = 1) and polyethylene terephthalate are major solid wastes due to the growing Li-ion battery market and widespread plastic usage. Here we propose a synergistic pyrolysis strategy to recover valuable metals by thermally treating LiNi1/3Co1/3Mn1/3O2 and polyethylene terephthalate. With polyethylene terephthalate assistance, LiNi1/3Co1/3Mn1/3O2 decomposes at 400 °C, and fully converts to Li2CO3, MnO, and Ni-Co alloy at 550 °C within 30 min, using a 1.0:0.3 mass ratio of LiNi1/3Co1/3Mn1/3O2 to polyethylene terephthalate. Furthermore, density functional theory calculations confirm the preference for O-Li bonding. Surface adsorption and free radical/gaseous reduction reactions explain the role of polyethylene terephthalate in promoting lattice destruction. The complete decomposition facilitates efficient post-treatment, achieving over 99% recovery of Li, Ni, Co, and Mn via water washing. Regenerated LiNi1/3Co1/3Mn1/3O2 was synthesized by using recovered Li- and transition metal-containing products as feedstocks. This study provided a chemical-free, energy-saving, and scalable recovery strategy while addressing polyethylene terephthalate waste minimization.

A comprehensive pyrolysis-gas chromatography/mass spectrometry analysis for the assessment of microplastics in various salts

Analytical pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS) was chosen to quantify microplastics(MPs) in edible salts: sea salt(SS), deep-sea salt(DSS), rock salt(RS), and lake salt(LS). Samples were filtered by two-step using 20 μm(MPs20) and 1 μm(MPs1) filters. Two Py-GC/MS methods with split ratios of 100/1 for high-level and 10/1 for low-level MPs were used. Quality control measures were taken to avoid pre-contamination. Methods showed high linearities (R2 > 0.995) and recoveries (84.2–118.1 %) for standards, polyethylene(PE), polypropylene(PP), polystyrene(PS), and polyethylene terephthalate(PET). SS showed highest MPs concentration (584.5 ± 204.4 μg/kg), followed by RS(34.2 ± 16.7 μg/kg) and LS(6.2 μg/kg). Over 7.2 % of detected MPs in SS and RS were smaller than 20 μm. PE, PP, and PET comprised 98.4 % of MPs in SS and 88.1 % in RS. MPs contamination from packaging materials was experimentally confirmed by the presence of similarly shaped PS particles in RS. MPs annual exposure was highest in SS(2304 μg/person), followed by RS(135 μg/person), and LS(24 μg/person), indicating substantial variation in exposure based on salt type.

Sensitive electrochemical sensing of carbosulfan in food products on laser reduced graphene oxide sensor decorated with silver nanoparticles

A simple, low-cost, eco-friendly, highly sensitive and selective electrochemical sensor based on laser reduced graphene oxide (LrGO) decorated with silver nanoparticles (LrGO/AgNPs) on a recycled green polyethylene terephthalate (PET) substrate was fabricated for the detection of carbosulfan in food products. An inexpensive disposable PET substrate was used to fabricate the flexible sensor using eco-friendly laser printing. Electrochemical investigations and surface characterization of sensor surfaces were performed with cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, the LrGO/AgNPs sensor showed a well-developed CV peak current with a good linear dynamic range (LDR) from 0.01 to 10 mg·kg−1 for the determination of carbosulfan with a limit of detection (LOD) of 0.005 mg·kg−1. The LrGO/AgNPs sensor was successfully applied for CV determination of carbosulfan in food products (apples, oranges and basmati rice) with a promising recovery from 90 % to 105 % and relative standard deviations (RSD) lower than 5 %. The novel sensor showed remarkable sensitivity, selectivity, reproducibility, and long-term stability. Therefore, this study showed that the fabricated electrochemical LrGO/AgNPs sensor is an excellent tool for the determination of carbosulfan in food products.

Chemical recycling of polymer contaminated poly(ethylene terephthalate) by neutral hydrolysis

Plastic recycling is gaining traction to reduce the demand for fossil resources for plastic production. Poly(ethylene terephthalate) (PET), mainly used in the packaging and textile sectors, is often isolated in the sinking fraction during the density-based separation of mixed plastic waste streams. The heterogeneity of the sinking fraction makes direct mechanical recycling of PET impossible. Therefore, neutral hydrolysis of PET was investigated in the presence of other polymer contaminants to study their impact on the neutral hydrolysis of PET. PA6, PC, POM, and PVC were found to decompose during hydrolysis, whereas ABS, PMMA and a mixture of PE, PP and PS was chemically inert during the hydrolysis treatment. The subsequent BHET synthesis with excess ethylene glycol was performed directly on a mix of the polymer contaminated hydrolysis products or a hydrolyzed post-consumer plastic waste fraction. BHET was successfully formed in the plethora of decomposition products in the synthesis, and a subsequent recrystallization recovered the BHET in high purity with only water being used as solvent. This demonstrated a robust method to handle PET fractions in mixed plastic waste that can be applied without purification prior to BHET synthesis – enabling chemical recycling of PET.Abbreviations: ABS, Poly(acetonitrile-butadiene-styrene); ATR-FTIR, Attenuated Total Reflectance Fourier Transformed Infrared Spectroscopy; BC, Bis(2-Hydroxyethyl) terephthalate crystals; BHET, Bis(2-Hydroxyethyl) terephthalate; DMSO, Deuterated dimethyl sulfoxide; DSC, Differential Scanning Calorimetry; EG, Ethylene glycol; 1H NMR, Proton Nuclear Magnetic Resonance; Hm, Melting enthalpy; Oligo, Oligomers; PA6, Polyamide 6; PC, Polycarbonate; PE, Polyethylene; PET, Poly(ethylene terephthalate); PMMA, Poly(methyl methacrylate); POM, Polyoxymethylene; PP, Polypropylene; PS, Polystyrene; P, Purity; PVC, Poly(vinyl chloride); rpm, Revolutions per minute; SPHP, Solid Phase Hydrolysis Product; Ti(IV)OBu, Titanium(IV) butoxide; Tm, Melting temperature; TPA, Terephthalic acid; Wt, Weight; Y, Solid Phase Hydrolysis Product yield; Yt, Bis(2-Hydroxyethyl) terephthalate yield; ν, IR stretching mode; δ, IR bending mode; ω, IR wagging mode.

Microplastics' impact on soil health and quality: Effect of incubation time and soil properties in soil fertility and pollution extent under the circular economy concept.

The aim of the present study is to highlight the effect of two commonly used plastics, polyethylene (PE) and polyethylene terephthalate (PET), on the quality and health indices of soil. To this end, a pot experiment was carried out using two soils, one acidic and one alkaline. The soil samples were collected from rural areas of central and Northern Greece and had similar particle size composition and almost equal copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) concentrations. PE and PET microplastics (MPs) were added into the soil samples in two ratios (2% and 4% v/v) and remained in the soils for 20, 60 and 120 days. Then, the changes in the properties, nutrients, potentially toxic elements and health indicators of the soil samples were measured. PE addition at 4% v/v caused the maximum increase in trace element availability when it remained in the soil sample for 120 days. In contrast, PET addition caused a maximum decrease in the DTPA-extractable concentration of toxic elements (Cd and Pb), after 120 days of incubation in acid and alkaline soil. The present work provides a fresh perspective evaluating MPs from unwanted waste to materials with potential positive benefits, enhancing the circular economy approach to soil systems. Knowledge of the MPs present in soils, along with physicochemical soil properties, including their nutrient and toxic element content, are critical aspects that need to be addressed to ensure that soil quality and health are not adversely affected.

Microplastics in stools and their influencing factors among young adults from three cities in China: A multicenter cross-sectional study

The mass concentration of microplastics in stools and influencing factors remain unclear. The aim was to investigate the types and mass concentrations of microplastics in the stools of young college students and to explore potential influencing factors. Twenty-six participants were recruited from colleges in each city using stratified simple sampling, including Changsha, Shanghai, and Changchun. Participants’ dietary and fluid intake behavior was recorded using the 3-day 24-h dietary questionnaire and the 7-day 24-h fluid intake record, respectively. Lifestyle factor information related to microplastic exposure was collected through a microplastic exposure questionnaire. Stools were collected and detected using pyrolysis gas chromatography–mass spectrometry (Py-GCMS) method. Eventually, 78 participants completed the study. The detection rate of microplastics, including polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET), in stools was 98.7%, with a total mass concentration of 54.7 (10.1–102.7) μg/g. There were differences in the total mass concentrations of microplastics in the stools of participants in three cities, namely Changsha, Shanghai, and Changchun, which decreased sequentially (χ2 = 47.819, P < 0.05). Participants with a relatively high frequency of takeaway food consumption had higher total mass concentrations of microplastics mass concentrations in stools (χ2 = 7.390, P < 0.05). Participants with a relatively high frequency of consuming reheated food had a greater mass concentration of PET microplastics (χ2 = 6.117, P < 0.05). The total mass concentration of microplastics, as well as the mass concentrations of PE, PVC, PP, and PA66, in the bottled water intake group were greater than those in the nonintake group (all P < 0.05). Overall, the total mass concentration of microplastics in stools was related to residential city, consumption of reheated food, and bottled water intake (all P < 0.05). Young college students generally experience microplastic exposure, with the main types being PE, PVC, PS, PP, PET, and PA66. Living location, reheated food consumption, and bottled water intake were factors influencing microplastic exposure.

Unveiling the Mechanics Behind Polyimide's Friction-Greening Phenomenon.

Polyimide (PI) has been widely used as a flexible substrate in the OLED display industry to achieve folding and other functions. However, it has unintended side effects, such as friction-greening, a green screen phenomenon caused by friction after prolonged usage. This is related to drifting TFT characteristics caused by charge accumulating in the PI in combination with the high efficiency of green pixels. In this study, the mechanism of the influence of PI structure on friction-greening was investigated. Increasing the process temperature from 350 °C to 470 °C, the chain segment structure within the PI became more regularized. Thus, the material had higher conductivity and shallower trap energy levels, which was confirmed by X-ray small angle scattering, dielectric, photoluminescence, and other methods. Under prolonged discharge conditions, less charge accumulated within PI, thus effectively mitigating the threshold voltage drift of the thin-film transistor (TFT). These results will contribute to the further optimization of the process and the development of PI materials.

Sub-millimeter scale 3D integration strategy enables ultrahigh-density and ultralow-crosstalk flexible tactile sensor array for robotic e-skin application

The rapid development of intelligent robots and wearable electronics brings great demand for flexible tactile sensor arrays with high sensitivity, fast response and high spatial resolution. However, simultaneously achieving high sensing performance and low crosstalk remains a fundamental challenge as sensor unit size is further reduced and array density increases. This work proposes a novel design and assembly strategy based on a mechanical microlattice structure, combined with in-situ laser direct writing and batch transfer techniques, to address the challenges from sub-millimeter active material array fabrication to 3D tactile sensor array integration. Additionally, the one-step preparation of high-consistency microcones on flexible substrates during laser direct writing enables the sensor to achieve a high sensitivity of 2.68 kPa−1 and a rapid response time of 50 ms. Both finite element simulation and experiments validate that the meticulously engineered mechanical microlattice structure, which incorporates a multi-material Young’s modulus gradient design, effectively concentrates external pressure on the pressed sensor units while shielding unpressed units, significantly mitigating the crosstalk and facilitating an ultrahigh resolution of ∼ 1 mm. Finally, the multipoint precision detection capability of the fabricated ultrahigh-density (over 113 units/cm2) tactile sensor array is verified as robotic e-skin for object grasping and pattern recognition.

Perfect Ultraviolet Absorbers via Disordered Polarizonic Metasurfaces for Multiband Camouflage and Stealth Technologies

AbstractAchieving multiband camouflage through the integration of ultraviolet (UV) absorption, visible light camouflage, and infrared signature modulation has long posed a challenge in material science. Leveraging the polarizonic concept, the study demonstrates, for the first time, the broadband camouflage system that adheres to the golden rule by achieving near‐perfect UV absorption (99.96%) across the UV‐A, UV‐B, and UV‐C ranges. This system is also visibly colored to blend with its environment and leaves no thermal signature in the IR. Traditionally, earth‐abundant metals, such as iron, are not considered viable for plasmonic color applications due to their high optical losses and oxidation susceptibility that degrade their optical properties. However, contrary to conventional assumptions, the study introduces a sustainable color palette derived from transparent and grey earth‐abundant materials, offering novel approaches to color, stealth, and energy‐harvesting metasurface‐driven technologies. The simple, cost‐effective, and environmentally friendly co‐sputtering fabrication method highlights the impact of the polarizonic concept and its novel dipolar image interference phenomena on flexible substrates therefore passivating the way for scalable and sustainable solutions in next‐generation camouflage systems with potential applications in UV‐protective coatings, photolithography, and anti‐counterfeiting technologies.

Highly active cobalt oxide-palladium nanohybrid catalyst enables selective electrocatalytic synthesis of glycolic acid

Glycolic acid is a unique value-added chemical, while its large-scale production is limited by harsh synthesis conditions and poor selectivity. Herein, we have ingeniously constructed a highly active cobalt oxide-supported palladium electrocatalyst on nickel foam (Pd-Co3O4/NF) for ethylene glycol oxidation to glycolic acid with a high Faradaic efficiency (93.1 %) at ultra-low potential (0.9 V vs. RHE). In situ Fourier transform infrared spectroscopy revealed the pathway of ethylene glycol oxidation reaction (EGOR). The theoretical results reveal that Co3O4/NF can effectively promote the formation of *OH and weaken the adsorption of toxic *CO intermediates on Pd-Co3O4/NF. And the downshifted d-band center of Pd-Co3O4/NF is inducive to facilitate the desorption of GA from the Pd surface, prevents the excessive oxidation thus improving the selectivity. Moreover, Pd-Co3O4/NF exhibits considerable anode current density with respect to electro-reforming polyethylene terephthalate (PET)-derived EG oxidation, accompanied by the generation of green hydrogen at the cathode. This work puts forward an innovative approach for catalyst construction toward EGOR and highlights the strategy of electro-upcycling of PET.

Delving into textile fast pyrolysis: A holistic study on the effects of feedstock and temperature variability

Perpetual fast fashion wave, dismal global recycling rate, and poor circularity of textiles urged sustainable textile waste disposal solution in lieu of incineration and landfilling. Herein, textile fast pyrolysis was mooted as a promising solution by dint of its fast disposal rate, mild pollutant emission, and multiple value-added products formation. Following ill-defined thermochemical behaviour of individual textiles, in-depth experimental exploration on textile fast pyrolysis was supplemented by feedstock characterization, product distribution, and product characterization to unravel the effects of feedstock (natural/synthetic) and temperature (500–900oC) variability on pyrolysis products. Textile fast pyrolysis harnessed pyrogas with two variable products, viz. retrievable chars and oils [natural textiles: cotton (C), denim (D), & cashmere/plant fibre (CP)] or non-retrievable chars and waxes [synthetic textiles: polyester (P), P/acrylic (PA), & P/cotton (PC)]. Melting and high aromaticity of polyethylene terephthalate (PET) rendered the synthesis of non-retrievable chars and waxes, separately. Given monotonic char yields (7.31–24.19 wt%) reduction with temperature, the oil/wax (53.19–75.19/60.46–70.52 wt%) and gas (13.44–33.67 wt%) yields were negatively correlated to each other. Twill-woven network of D contributed to exclusively high BET surface area of D chars (132.64–217.10 m2/g). All natural textile chars (28.56–32.88 MJ) exhibited comparable higher heating value (HHV) to commercial coals/coke (14.77–34.39 MJ/kg) and biochars (7.26–33.37 MJ/kg). Compared to the commercial fuels, raw textile oils (incombustible-10.14 MJ/kg) and textile waxes (15.88–23.18 MJ/kg) were inferior fuels with low HHV. Nonetheless, cotton (C & D) oils, CP oils, and P-based textile waxes had respective enriched content of levoglucosan (6.85–34.38 area%), triacetoneamine (6.22–21.09 area%), and benzoic acid (16.37–46.55 area%). Considering noteworthy H2 formation data sets (700–900oC; C700 only), natural textile pyrogas (62.75–79.02%) had greater syngas (H2 & CO) composition than synthetic textile pyrogas (62.48–68.23%). At optimal temperature of 900oC, textile fast pyrolysis generated pyrogas with H2:CO ratios (1.30–3.49 ≈ 2) that nearly ideal for Fischer-Tropsch synthesis. Conversely, textile fast pyrolysis also emitted pollutant gases that differ between natural (NH3, N2O, NO, & SO2) and synthetic [NH3 (excluding P), N2O, & NO2] textiles.