Mixed Plastic Waste Research Articles (Page 1)

This article outlines three strategies to transform mixed plastic waste into fuels and new chemicals, offering a multiple path solution for a circular economy.

Alkaline molten salt thermal treatment of mixed waste plastics for oil production: Insight into the effects of molten salt alkalinity and plastic molecular structure

Rapid detection and identification of plastic waste based on multi-wavelength laser Raman spectroscopy combining machine learning methods.

Upcycling mixed plastic waste as a replacement for natural aggregates in concrete: A critical review

The escalating global production of plastics and the depletion of fossil fuel reserves underscore the urgency of sustainable waste-to-energy strategies. This study investigates the staged catalytic pyrolysis of polypropylene (PP), high-density polyethylene (HDPE), and their blends for the production of liquid fuels. Experiments were conducted in a semi-batch reactor at 450 °C (Stage A) and 500 °C (Stage B), with bentonite as catalyst. Product yields and compositions were quantified via mass balance and GC–FID analysis. Results revealed strong feedstock-dependent behaviors: HDPE exhibited superior liquid recovery (81.96% in Stage A, 88.24% in Stage B) with minimal char, whereas PP was prone to higher char and gas formation. Co-pyrolysis demonstrated synergistic effects, with asymmetric mixtures outperforming single-polymer systems. Notably, the 70% PP–30% HDPE blend achieved the highest liquid recovery (95.07%) and lowest gas fraction (4.92%) during secondary cracking, while the 30% PP–70% HDPE blend enhanced diesel- and kerosene-range fractions. GC–FID analysis confirmed that PP favored gasoline-range hydrocarbons, while HDPE enriched middle distillates. The tunability of hydrocarbon distribution through feed composition highlights staged pyrolysis as a robust pathway for transforming mixed plastic waste into targeted fuel-range hydrocarbons. These findings provide actionable insights into optimizing product selectivity and yield, advancing the integration of polyolefin pyrolysis into circular economy and sustainable energy frameworks.

Sustainable Solution for Road Pavements and Review of Bituminous Mixes with Mixed Waste Plastic

Development of defined bacterial consortium as a bioaugmentation product for degrading mixed plastic wastes and plasticizers in simulated landfill.

In this study, a thermogravimetry approach was employed to investigate the thermal parameters of waste polypropylene (PP), mixed wood biomass (WB), cardboard (CB), and their blends during co-gasification under oxidative conditions at varying heating rates. The resulting data were used to quantify the mass loss profiles for each feedstock and to assess the effects of blending on process temperatures (onset and end), residual mass, and activation energies. Activation energies (Ea) were determined using three iso-conversional methods: Friedman, Kissinger–Akahira–Sunose (KAS), and Numerical Optimization. Among the feedstocks, PP exhibited the highest thermal stability. When blended with either CB or WB, both onset and end temperatures significantly (p < 0.05) increased with rising PP content. These trends were consistent at heating rates of 20 and 40 °C/min. In contrast, CB/WB blends showed no notable variation in onset temperature across blend ratios at either heating rate. However, PP/CB blends exhibited significantly lower residual masses (up to a six-fold decrease) with increasing PP content. Since both PP and WB individually yielded very low residual mass (<2 wt%), increasing PP content in PP/WB blends did not significantly affect the residual mass. Overall, higher heating rates shifted thermal decomposition into higher temperature regimes in both individual and blended feedstocks, but had no impact on residual mass. The Ea of WB was the highest (138–139 kJ/mol), followed by CB (113–116 kJ/mol) and PP (56–63 kJ/mol). The blending of PP/CB and CB/WB resulted in reduced Ea values compared to the pure feedstocks, indicating a positive synergistic effect during co-gasification. In essence, the co-gasification of mixed plastic waste presents a promising strategy for sustainable waste management and energy recovery.

Acrylonitrile–butadiene–styrene (ABS) has been widely used as an engineering thermoplastic, and the increasing post-consumer waste of ABS plastics calls for efficient and sustainable recycling technologies. The recent advances in ABS recycling technologies were investigated to enhance material recovery, purity, and environmental performance. Thermo-oxidative degradation compromises mechanical integrity during reprocessing, while minor reductions in molecular weight increase melt flow rates. Surface modification techniques such as boiling treatment, Fenton reaction, and microwave-assisted flotation facilitate the selective separation of ABS from mixed plastic waste by enhancing its hydrophilicity. Dissolution-based recycling using solvent and anti-solvent systems enables the recovery of high-purity ABS, though some additive losses may occur during subsequent molding. Magnetic levitation and triboelectrostatic separation provide innovative density and charge-based sorting mechanisms for multi-plastic mixtures. Thermochemical routes, including supercritical water gasification and pyrolysis, generate fuel-grade gases and oils from ABS blends. Mechanical recycling remains industrially viable when recycled ABS is blended with virgin resin, whereas plasma-assisted mechanochemistry has emerged as a promising technique to restore mechanical properties. These recycling technologies contribute to a circular plastic economy by improving efficiency, reducing environmental burden, and enabling the reuse of high-performance ABS materials.

Maximising naphtha-range hydrocarbons from thermal pyrolysis of polyolefin-rich mixed plastic waste by split-plot response surface methodology.

Valorizing non-condensable pyrolysis gases from mixed plastic waste: A comprehensive parametric study of the cross-metathesis reaction for propylene production

Thermochemical conversion of mixed plastics from car dismantling by pyrolysis and distillation and potential applications of the products.

Waste from used tires and plastics poses a significant environmental challenge due to their non-biodegradable nature. These materials take hundreds to thousands of years to decompose naturally. Every year, plastic and tire waste increase in correlation with population growth and vehicle usage. This waste management is frequently insufficient, resulting in significant adverse effects on human society. One of the effective solutions to the environmental challenges posed by used tires and plastic waste is converting them into crude oil and solid char using pyrolysis technology without a catalyst. This process is a thermochemical decomposition that occurs at high temperatures without oxygen. Pyrolysis breaks down the complex chemical structure of plastics and tires into simpler, valuable components. After being cut into small pieces of 3 cm to 5 cm, the feedstock was placed into a pyrolyzer, with each batch weighing 500 grams, to produce pyrolytic liquid oil and char. The pyrolysis temperature was set at 350 ℃ for all experiments, with a heating rate of 10 ℃/min and a holding time of 90 minutes. The process was followed by distillation at two different temperatures, 250 ℃ and 350 ℃, with a heating rate of 10 ℃/min. This distillation process separated the pyrolytic oil based on its boiling points to obtain distillate liquid oil. Two types of distillate liquid oil were produced and analyzed using gas chromatography and mass spectrometry to determine their chemical composition and compounds. It was found that both distillate oils contained similar organic compounds, primarily consisting of complex mixtures of C12–C31 hydrocarbons, which are typical of heavy fuel oils. The heating value of both distillate oils was 31.26 MJ/kg. Additionally, the residual char produced during the process had a calorific value of 21.73 MJ/kg, indicating its potential use as a solid fuel. These properties demonstrate the potential of the products to substitute conventional fuels for heavy machinery or industrial boilers. This study confirms that used tires and plastic waste can be converted into heavy fuel oils, offering great potential as alternative energy sources.

Practically simple, catalyst-free, and scalable approach for all-component upcycling of mixed PVC/PA plastics.

The escalating global plastic waste crisis, particularly that of poly(ethylene terephthalate) (PET), necessitates innovative recycling approaches that align with the concept of a circular economy. In this study, we present an efficient and sustainable strategy for PET depolymerization via glycolysis, employing a magnetically recoverable nano zerovalent iron (nZVI) catalyst. Key reaction parameters, including the ethylene glycol (EG)/PET ratio, catalyst loading, reaction time, and temperature, were systematically optimized, achieving complete PET conversion and a bis(2-hydroxyethyl) terephthalate (BHET) yield exceeding 90%. The catalyst exhibited excellent reusability over four cycles, and its selectivity was demonstrated in mixed plastic waste systems where PET was effectively depolymerized, while bisphenol A polycarbonate (BPA-PC) remained largely unaffected. The comparison with BPA-PC highlights the specificity of the nZVI catalyst toward ester bond hydrolysis in PET, while BPA-PC, a carbonate-based polymer with a difference in structure and glycolysis reactivity, remained resistant under the same reaction conditions. Moreover, the process integrated efficient recovery and recycling of unreacted EG, further enhancing its sustainability. These findings underscore the potential of nZVI-catalyzed glycolysis as a green, economically viable solution for advanced PET recycling and waste management.

The increasing accumulation of plastic waste in the environment brings about a potential danger for ecosystems and human society; mechanical recycling remains one of the most economical strategies to deal with the growing crisis of plastic pollution; however, it suffers from substantial performance deterioration when processing immiscible blends of polyethylene and nylon plastics. Here, we report on-demand nonalternating copolymerization of ethylene with carbon monoxide (CO) via a facile tandem gas compensation strategy, which achieves a precision control over carbonyl incorporation with uniform distribution across a broad range (0-50%). Such a synthetic advance offers a unique multiblock structure having short polar segments ((CH2-CH2)n-CO-) (n < 4) and extended nonpolar methylene sequences (n > 4). Remarkably, the resulting quasi-multiblock copolymer (q-MBCP) delivers a robust compatibilization for polyethylene and nylon blends, thus transforming brittle materials into mechanically tough composites. This work elucidates the mechanistic evolution between nonpolar polyethylene and polar alternating polyketone phases, while offering a practical and sustainable solution to advance closed-loop recycling of mixed plastic waste.

Plastics are essential to modern society, but their low recycling rates and inefficient end-of-life management pose a significant environmental challenge. Herein, the efficient strategy for upcycling postconsumer poly(ethylene terephthalate) (PET) waste into robust, closed-loop recyclable vitrimer plastics and composites is presented to address this issue. The catalyst-free aminolysis utilizes readily available amines to deconstruct diverse PET wastes into macromonomers, which are upcycled into vitrimers, exhibiting superior mechanical properties and exceeding the ultimate tensile stress and Young's Modulus of virgin PET by 80% and 150% respectively. These vitrimers exhibit excellent healability, shape memory, thermal reprocessability, and closed-loop chemical recyclability, enabling quantitative macromonomer recovery even from mixed plastic waste streams and glass/carbon fiber reinforced vitrimer (G/CFRV) composites. Furthermore, the vitrimer resin yields robust GFRV and CFRV composites with tensile strengths exceeding those of traditional epoxy composites by 100% and 80%, respectively, while maintaining complete chemical recyclability of both constituent materials. A preliminary technoeconomic analysis confirms the costeffectiveness and competitiveness of the facile PET deconstruction approach, which is potentially adaptable to other condensation polymers. This study presents a facile approach to upcycling plastic waste into circular plastics and composites, offering a sustainable solution to global plastic waste management and fostering a circular economy.

In our research, we investigated the chemical foaming of mixed plastic waste granulate (VMHD) using a combination of endothermic and exothermic foaming agents. We found that increasing the exothermic foaming agent improved cell distribution but reduced flexibility and impact resistance. The highest porosity (30.04%) was achieved with 0.5% endothermic and 3.5% exothermic foaming agents. Our results indicate that the proper ratio of foaming agents is crucial for optimizing the mechanical properties of the material.

The rapid accumulation of plastic waste underscores the urgent need for effective recycling strategies, yet conventional approaches are hindered by the immiscibility of chemically dissimilar polymers, which phase-separate upon blending and yield poor material properties. This study demonstrates a versatile strategy for electrostatic compatibilization, utilizing acid-base proton transfer between minimally functionalized polymers. Waste-derived polystyrene (PS) was successfully modified with <4 mol % acid groups, while amorphous polybutadiene (PBD) was functionalized with <6 mol % diethylamino base groups and subsequently hydrogenated to yield semicrystalline polyethylene (PE) with the same functionalization level as the PBD. In both cases, blending with functionalized PS produced optically transparent, mechanically robust films. Notably, increasing charge density from 1.0 to 3.5 mol % significantly reduced domain sizes, indicating enhanced compatibilization, while increasing PS molecular weight from 28 to 470 kDa led to a three-order-of-magnitude increase in toughness. In PE/PS blends, the preservation of crystallinity during melt reprocessing was achieved by maintaining low functionalization levels, demonstrating compatibility without sacrificing critical material properties. These findings establish electrostatic compatibilization as a powerful, scalable platform for creating high-performance materials from chemically diverse and mixed plastic waste streams.

ABSTRACTWe have been developing a solvent‐based plastic recycling technology called STRAP. The technology is based on dissolving a targeted plastic resin in a specific solvent that does not dissolve other resins. We have demonstrated STRAP in thousands of bench scale experiments for a large variety of wastes. Recently we have demonstrated the technology for PCR, using mixed plastic wastes (MPWs), from a wet Material Recovery Facility (MRF). The process includes (1) infrared (IR) characterization to determine the plastic composition for accurate selection of the solvent to be used for the extraction of the pure resins. (2) Shredding to the right size and aspect ratio required for flowable and fast dissolvable process. (3) Mixing the MPW in the first solvent to dissolve the first resin. (4) Filtration of the solution plastic blend, to separate the nondissolved plastic from the solution. (5) Further filtration of the solution to remove micron‐sized particle of pigments and fibers. (6) Cooling for precipitation. (7) Filtration of pure resins. (8) Drying of a pure resin. (9) Extrusion of the resin to pellets. (10) Generating films or other products from the pure resin. Steps 1–10 can be considered as one‐cycle that extracted the first resin. (11) A second resin can be extracted with a respective solvent from the plastic that did not dissolve in the first cycle and following steps 1–10 described above. The process also includes characterization of interim and final products. The effort includes building a pilot system at 25 kg/h throughput. We will present specific results for various PCR.