Waste Polystyrene Research Articles

Trash to treasure: Transforming wasted polystyrene foam to conductive fibers by polymer pyrolysis deposition on glass fibers

Recycling and utilization of waste polymers is an important part of the sustainable development of fossil resources. In this work, carbon-coated glass fibers (CGFs) with high electrical conductivity were prepared through a low-cost polymer pyrolysis deposition (PPD) method by using waste polystyrene foam as carbon source. The CGFs exhibited an electrical conductivity of up to 615 S/m and the conductivity of carbon coating layer reached to 5.5 × 104 S/m. The electrical conductivity was related to the mass ratio and graphitization of the carbon layer, and the C–Si bonds provide a tight connection between the carbon layer and the glass fibers. Overall, this work found a way for transforming waste polymers to conductive fibers and this strategy would not only lower the cost of conductive fibers but also solve reutilization of the white pollution.

Separation of nanoplastics from synthetic and industrial wastewater using electrolysis-assisted flotation approach: A green approach for real-time contaminant mitigation

Nanoplastics pose a significant global environmental concern, as they can accumulate emerging pollutants and enter the food chain, endangering human health and ecosystems. Wastewater treatment plants (WWTPs) have been identified as the primary source of micro and nanoplastic contamination, necessitating the development of effective removal methods. This study investigates the efficacy of electrolysis-assisted flotation (EF) process for removing nanoplastics from synthetic wastewater, using polystyrene-type nanoparticles synthesized from expanded polystyrene waste (EPS) as representative nanoplastic contaminants. Electrolysis experiments were conducted using parallel aluminium electrodes under low-voltage conditions. The study systematically explores the influence of various process parameters, including electrode spacing, salt concentration, nanoplastics concentration, and applied voltage, on the removal efficiency of nanoplastics. The removal efficiency was evaluated using a turbidity meter and dynamic light scattering technique. The derived count rate (DCR) obtained from dynamic light scattering supplements the nephelometric turbidity units (NTU) and provides a reliable estimate of the nanoplastics sample concentration. Under optimized conditions, with a specified electrolyte concentration and pH of 7.2 ± 0.3, the EF process achieved an impressive removal efficiency of nearly 95 % (94 % per DCR). A notable advantage of the proposed method is forming a foamy layer on top of the reactor when nanoplastics and coagulants are mixed, facilitating easy removal by simple scraping. This study provides valuable insights into developing an eco-friendly and sustainable approach for the large-scale removal of nanoplastics. The results contribute to advancing wastewater treatment strategies and addressing the pressing issue of nanoplastic pollution.

Growing of 2D/3D graphene structures on natural substrates from aromatic plastic wastes by scalable thermal-based upcycling process with a comparative CO2 footprint analysis

Recycling aromatic plastics, such as polystyrene (PS) and polyethylene terephthalate (PET), is complex and strongly sensitive to the process design and conditions due to the presence of polycyclic aromatic hydrocarbons and interunit CO and/or CC linkages. Herein, the upcycling process becomes crucial to attain high-value-added products from aromatic plastics. With this study, graphene growth was achieved on the natural substrates of talc and organically modified montmorillonite (OMMT), from waste PS and PET sources via a sustainable, affordable, and environment-friendly upcycling technique. This promising method promotes the formation of 2D and 3D graphene structures from waste PS and PET. This provides dimension-controlled graphene growth by tailoring the substrate type and size, surface composition of the substrate, and the degree of aromaticity in the polymer. In addition, polymer processing techniques of twin-screw extrusion and thermokinetic mixing, were investigated in the development of graphene-grown hybrid additives to tailor the degree of crystallinity. Regarding structural characterization results, a high shear rate mixer led to the change in crystalline planes of talc, whereas conventional twin screw extrusion preserved the structure of talc indicating that high shear rate triggered the exfoliation of talc. Furthermore, a systematic life cycle assessment was conducted to evaluate the CO2 footprint of upcycled graphenes grown on talc and OMMT compared to graphene produced from graphite. Upcycled graphene structures obtained by direct carbonization and even catalyst impregnated natural substrate-based graphene growth process with PS or PET source have comparably lower CO2 emission than graphene received from graphite. Therefore, these newly developed and upcycled hybrid additives opens a way for the conversion of aromatic complex plastic wastes into value-added nanomaterials being candidate as reinforcing agent by adopting a circular economy model.

Various waste polystyrene for useful membrane fabrication: Comparative experimental study

Plastic waste recycling is drawing great attention to prevent the harmful effects resulting from the accumulation of plastic waste, especially as an integrated waste-to-product process. This study introduced a comparative study of two polystyrene (PS) wastes for polymeric membrane fabrication. Two types of polystyrene wastes, transparent and white-coloured, used for yoghurt packaging, were utilized. The commercial PS membrane was also fabricated for comparison. Polystyrene membranes were prepared by a non-solvent induced phase separation (NIPS) method. The prepared membranes were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), measurements of contact angle (CA), porosity, and pore size distribution. According to the results, the prepared membranes showed an asymmetric structure with a blocked skin layer. Also, the prepared membrane surfaces were partially hydrophilic. Increasing polymer concentration (from 10 to 18 wt.%) enhanced the structural homogeneity of the membrane by obtaining smaller pores. On the other hand, the membranes' porosity decreased with the rise in the polymer concentration. Measurements highlighted the successful fabrication of similar membrane characteristics using two types of PS wastes, making them vivid candidates for water desalination and gas separation applications.

Agricultural Crop Rresidues and Polystyrene Waste for the Production Thermal Insulators

Abstract Renewable building materials that are produced from agricultural and industrial waste have become more demanded in engineering applications for their sustainability and have little harm to the environment. They are also considered thermal insulators that reduce energy consumption, with their great importance in producing valuable materials from harmful waste. In this research, there are four types of locally available renewable materials (rice husk, sawdust, rice husk powder, and polystyrene waste). It is used to produce thermal insulators with compressive strength (2.08 - 5.992 MPa). The thermal conductivity of the sample ranges between 1012-1433 kg/m3 and 0.118-0.362 W/m.K, respectively. The lowest thermal conductivity is. 0.118 W/mK was observed for the composite of rice husk powder with cement and sand, and the density was 1332 kg/m3. The lowest water absorption (15%) was found in the polystyrene sample. The tested samples showed potential to become thermal insulators and can be used in place of traditional materials in both internal and external building insulation applications. Extensive cement-based compounds some of which are summarized in Table 1 and compared with the results of this study

The Influence of Waste Plastic Fiber on the Characteristics of Light Weight Concrete with Expanded Polystyrene (EPS) as Aggregate

This research aims to create lightweight concrete mixtures containing waste from local sources, such as expanded polystyrene (EPS) beads and waste plastic fibers (WPFs), all are cheap or free in the Republic of Iraq and without charge. The modern, rigid, and mechanical properties of LWC were investigated, and the results were evaluated. Three mixtures were made, each with different proportions of plastic fibers (0.4%, 0.8%, 1.2%), in addition to a lightweight concrete mixture containing steak fibers (0.4%, 0.8%, 1.2%), in addition to a lightweight concrete mixture. It contains 20% EPS. The study found that the LWC caused by the addition of WPFs reduced the density (lightweight) of the concrete mixtures because EPS tends to form more blocks, absorb water, and dry the mixture. While the increase in WPF content increased in compressive strength, as the compressive strength of the concrete mix containing (EPS) was only 13.6 MPa, the compressive strength increased to 17.6 MPa when WPFs were added. The addition of plastic also increased the bending resistance, where the bending resistance of the concrete mix containing (EPS) was only 2.26 MPa and increased to 2.66 MPa when (WPFs) were added.

Removal of undissolved substances in the dissolution-based recycling of polystyrene waste by applying filtration and centrifugation

Polystyrene (PS) is a versatile polymer typically used in applications such as yogurt cups, packaging trays, disk cases and toys. To increase recycling rates of PS, dissolution recycling is being investigated, which involves the liquefication of the polymer in a suitable solvent, allowing deep cleaning of the polymer from impurities. Quite specific to PS is that polystyrene waste contains both general-purpose polystyrene and high-impact polystyrene (HIPS), which is composed of free PS and polystyrene-grafted polybutadiene particles. In this work the potential of filtration and centrifugation is analyzed with the aim of cleaning the polymer from both, insoluble PB-PS particles and pigments (TiO2, Cr/Sb/Ti oxide and carbon black). The dead-end lab scale filtration were performed at room temperature and at pressures between 1.5 and 30 bar. The pigments were successfully removed, yet, filtration of HIPS solutions results in low fluxes due to extreme membrane fouling caused by the PB-PS particles, which was confirmed by the application of pore-blockage filtration models. Alternatively, centrifugation at 14,052 G-force has shown to be a promising alternative to separate the particles from HIPS, resulting in 100% turbidity reduction. Equally, the separation of pigments was successful, highlighting that TiO2 and Cr/Sb/Ti oxide have shorter sedimentation times compared to carbon black. Finally, the two separation processes are tested on a PS rigid packaging waste sample coming from a sorting line and the results show that centrifugation allows a high turbidity reduction and that a two-step separation process starting with centrifugation for PB-PS particles removal can facilitate further downstream cleaning.

Nitrogen‐Enriched Porous Carbon Materials from Expanded Polystyrene Waste for Oxygen Reduction Reaction and Rechargeable Zinc–Air Battery

Transforming discardable solid waste like polystyrene (PS) foams into commercially useful applications like sustainable and eco‐friendly energy materials has attracted considerable attention. Herein, expanded PS waste is subjected to simple reactions (cross‐linking and pyrolysis) to obtain a high‐performing electrocatalyst for the oxygen reduction reaction (ORR). The optimized catalyst polystyrene‐pyrrole (PSP‐800) demonstrates good electrocatalytic ORR activity toward rechargeable zinc–air battery due to its high surface area, copious amount of micropores/mesopores, high nitrogen content, and a trace amount of Fe doping. Accordingly, PSP‐800 delivers a high onset potential (0.99 V) and a half‐wave potential of 0.88 V versus a reversible hydrogen electrode. Moreover, the rechargeable zinc–air battery using PSP‐800 as an ORR catalyst demonstrates improved stability and high‐power density (116 mW cm−2) compared to the standard Pt/C catalyst.

A Generic Platform for Upcycling Polystyrene to Aryl Ketones and Organosulfur Compounds.

Polystyrene (PS) is one of the least recycled large-volume commodity plastics due to bulkiness of foam products and associated contaminants. PS recycling is also severely hampered by the lack of financial incentive, limited versatility, and poor selectivity of existing methods. To this end, herein we report a thermochemical recycling strategy of "degradation-upcycling" to synthesize a library of high-value aromatic chemicals from PS wastes with high versatility and selectivity. Two cascade reactions are selected to first degrade PS to benzene under mild temperatures, followed by the derivatization thereof utilizing a variety of acyl/alkyl and sulfinyl chloride additives. To demonstrate the versatility, nine ketones and sulfides of cosmetic and pharmaceutical relevance were prepared, including propiophenone, benzophenone, and diphenyl sulfide. The approach is also amenable to sophisticated upcycling reaction designs and can produce desired products stepwise. The facile and versatile approach will provide a scalable and profitable methodology for upcycling PS waste into value-added chemicals.

Synthesis of PS/RB-Cs and its use in the treatment of water polluted with heavy metals

Polystyrene waste are non-biodegradable materials that causes harm to the environment. Red brick waste resulting from demolition and reconstruction are an obstacle to its disposal. To solve this problem and meet modern sustainability standards, this study utilized polystyrene (PS) foam and red brick construction waste to prepare composite materials (PS/RB-Cs) as a new efficient adsorbent. The PS/RB-Cs composite as an adsorbent was characterized using a UV–Vis Spectrophotometer, Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscope (SEM), and transmission electron microscopy (TEM), which showed a clear spectrum shift after using PS/RB-Cs as an adsorbent. The PS/RB-Cs was characterized by a porous structure with higher surface area and high stability. The efficiency of the PS/RB-Cs in treating water contaminated with heavy metals such as cobalt and nickel was verified under different initial concentrations, temperatures, doses, pH, and contact times. The experimental qe values were consistent with the qe calculated values and were approximately 8 mg/g. The adsorption isotherm models showed that the adsorption results fit the Langmuir, Freundlich and Flory-Huggins isotherm models and that the process was favorable. By applying pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models, the adsorption process was found to follow PSO. The findings of this research validated that the composite material that was prepared serves as a potent adsorbent for the treatment of water that has been polluted by heavy metals.

Polystyrene Waste Thermochemical Hydrogenation to Ethylbenzene by a N-Bridged Co, Ni Dual-Atom Catalyst.

Recycling waste plastics requires the degradation of plastics into small molecules. However, various products are widely distributed using traditional methods of depolymerizing polystyrene (PS) such as catalytic pyrolysis and hydrogenolysis. Here, we creatively report a N-bridged Co, Ni dual-atom (Co-N-Ni) catalyst for the targeted conversion of waste PS plastics to ethylbenzene via a pressurized tandem fixed-bed reactor where hydropyrolysis is coupled with downstream vapor-phase hydrotreatment. The Co-N-Ni catalyst achieves 95 wt % PS conversion with 92 wt % ethylbenzene yield, significantly superior to the corresponding single-atom catalysts, and enables degradation of real PS plastics. Theoretical calculations and experimental results demonstrate that the d-band center of metal atoms is well regulated in the Co-N-Ni catalyst. The Co site activates the C═C bond more easily, while the Ni site spatially optimizes the adsorption configuration of the styrene molecule due to the electronic interaction. This Co-N-Ni catalyst in the tandem reactor also shows excellent durability and provides a new direction for real plastic degradation.

Ultralow loaded waste polystyrene derived hyper-cross-linked polymer for incineration flue gas demercuration: Synergistic effect of transition metal and halogen species

Gaseous mercury pollution control is pressing to both human health and environment protection. Achieving high demercuration performance with the lowest possible amount of active species is critical for developing demercuration adsorbent. Herein, motivated by waste plastic recycling and flue gas demercuration, we report a cost-effective and mild method to reclaim waste polystyrene into highly porous hyper-cross-linked polymers for flue gas demercuration. The waste derived hyper-cross-linked polymer exhibits superior porosity and strong hydrophobic property. Further chemical modification at ultralow concentration (∼0.001 mmol/g) over pristine HCPs could promote the chemically Hg0 bonding ability thus obtaining remarkable demercuration ability (>90% in 15 mins for FeBr3-HCPs) under complicated flue gas conditions along with the interference of 1200 ppm SO2 and 10% H2O. Such HCP-based demercuration adsorbents could greatly surpass state-of-the-art adsorbents. Comprehensive characterizations and density functional theory calculations are performed to illustrate the interaction between HCPs substrate and different active species as well as the Hg0 removal process over metal and halogen sites. The activity of Fe sites can be optimized by surrounding Cl and Br sites thus promoting the Hg0 bonding and oxidation. This work could broaden the reutilization methods for waste polystyrene and contribute to the development of gaseous Hg0 control technology.

Heat treatment’s effect on properties of polystyrene from building demolitions

Polystyrene (PS) is a synthetic polymer widely used as a packaging material and in thermal insulation of buildings. At end-of-life, there are not many recycling management options of PS because of the reduced incentive and high cost. PS is non-biodegradable, and consequently, the disposal of this product causes serious health and environmental concerns. This study discusses the application of thermal treatment to modify the properties of PS waste foams. Both expanded and extended polystyrene were collected from building demolitions and subjected to different temperature treatments and duration. The effect of the treatment was investigated on the density, structure, glass transition temperature, mechanical properties (hardness, compression strength), thermal conductivity, and sound absorption of treated PS. The results showed that density increased with treatment temperature, which had a corresponding effect on the evaluated properties. The study concluded that thermal treatment is a beneficial way to improve the mechanical properties of PS waste from buildings. However, a trade-off between application and relevance still needs to be ascertained, as the thermal and acoustic insulation properties of PS decreased with the treatment.

Resource utilization of polystyrene waste by preparation of high performance dispersant for coal‒water slurry

ABSTRACT In present paper, structures and properties of degradation products of polystyrene (PS) waste were characterized by gel permeation chromatography (GPC), thermogravimetric (TG) analysis, Fourier transform infrared (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), and thus the degradation conditions including temperature, time, and assistant type and dosage were investigated and optimized. It is suitable to use 1.0 wt% K2S2O8 as an assistant to degrade PS waste at 300°C for 24 h. Subsequently by sulfonation and neutralization reactions, the degraded PS was prepared into sodium polystyrene sulfonate (PSS), a common dispersant for coal‒water slurry (CWS). The performance of PSS with different molecular weights and sulfonation degrees was studied. Experimental results showed that the PSS with the sulfonation degree of more than 75%, prepared from the degraded PS having number average molecular weight (M n) of about 9000, was appropriate for dispersion and stabilization of CWS suspensions. Additionally, compared with commercial dispersant NSF, the obtained PSS had a better performance for CWS. CWSs prepared with dispersant PSS exhibited pseudo-plastic or shear-thinning rheological behaviors. Combined with coal‒water slurry technology, a new approach is provided for resource utilization of PS waste.

Preparation of wood plastic composite from flax fibers and post consumed polystyrene foam based on environmental and economical scales

Due to the high cost of transportation and the lack of established, affordable recycling routes, the rate of recycling of previously used polystyrene foam is extremely low. In this study, a novel treatment technique will be used to examine the feasibility of using waste polystyrene foam as a raw material to produce wood plastic composite (WPC). Where, the recycled polystyrene (rPS) foam waste was first dissolved in methylene chloride and compounded directly with flax fiber (FF) and additives forming a composite paste. The composite paste was then passes through vacuum distillation process for drying the composite paste and also for solvent recovery to reuse it in a further process. The dried composite was processed through thermal mixer extruding and compression molding processes to form the final WPC. The study discovered that WPC with 60 parts per hundred parts of resins (phr) of FF and 2 phr of dioctylphthalate (DOP) may be used to create rPS/FF composite with a proper tensile strength of 19.3 MPa, flexural strength of 78 MPa and compressive strength of 173 MPa compared to another WPS,s based on PVC, HDPE and PP . In addition of that the resulted composite possesses a great potential in manufacturing WPC with environmental and economical demanding application as wooden furniture and as a wooden panels for cladding the exterior building faces.

Development of textile printing ink using expanded polystyrene waste as a binder

This research produced textile pigment printing paste using expanded polystyrene (EPS) as a binder, sodium alginate as a thickener, and ultramarine pigment. The printing paste production was optimized through response surface methodology, using central composite design (CCD). The dynamic viscosity of the produced printing paste samples ranges from 5200 to 5550.50 cP (Centi Poise). The Fourier infrared transform (FTIR) spectroscopy revealed the functional groups present in the printing paste. The result of the thermogravimetric analysis (TGA) conducted shows a first step decomposition of 94.14% that occurred at the range of 30.96°C–127.75°C. Differential scanning calorimetry (DSC) showed an endothermic transition at 119.44°C due to the absorption of energy during the breaking of printing paste bonds. Textile characterization such as wash fastness, croak fastness, and light fastness was carried out to determine the suitability of the print paste on cotton and polyester fabrics. The results of the fastness tests range from 4 to 5 for wash fastness, 3 to 4/5 for croak fastness, and 4 to 6 for light fastness. The optimum values of the model variables are thickener (50%), binder (40%), and pigment (5%). The performance of the printing paste as revealed from the results is moderate and comparable with textile printing paste suitable for commercial application.

Conversion of waste polystyrene into valuable aromatic hydrocarbons via microwave-assisted pyrolysis.

The prime objective of the current research work was to understand the role of microwave-assisted pyrolysis for the upgradation of expanded polystyrene (EPS) waste into valuable aromatic hydrocarbons. Ethyl acetate solvent was used to dissolve the EPS to enhance the homogeneous dispersion of EPS with susceptor particles. Biochar obtained from the pyrolysis was used as a susceptor. The design of experiments method was used to understand the role of microwave power (300 W, 450 W, and 600 W) and susceptor quantity (5g, 10g, and 15g) in the pyrolysis process. The pyrolysis was conducted till the temperature reached up to 600°C, and this temperature was achieved in the time interval of 14-38min based on the experimental conditions. The obtained average heating rates varied in the range of 15 to 41°C/min to attain the pyrolysis temperature. The EPS feed was converted into char (~ 2.5 wt.%), oil (51 to 60 wt.%), and gaseous (37 to 47 wt.%) products. The specific microwave energy (J/g) was calculated to know the energy requirement; it increased with an increase in susceptor quantity and microwave power, whereas specific microwave power (W/g) was a function of microwave power and increased from 15 to 30 W/g. The predicted values calculated using the model equations closely matched the actual values showing that the developed model equations via optimization had a good fit. The obtained pyrolysis oil physicochemical properties including viscosity (1 to 1.4 cP), density (990 to 1030kg/m3), heating value (39 to 42MJ/kg), and flash point (98 to 101°C) were thoroughly analyzed. The pyrolysis oil was rich in aromatic hydrocarbons and it was predominantly composed of styrene, cyclopropyl methylbenzene, and alkylbenzene derivates.

High-Efficiency Water Filtration by Electrospun Expanded Polystyrene Waste Nanofibers.

Nanofiber membranes were successfully synthesized from expanded polystyrene (EPS) waste with the addition of poly(vinylpyrrolidone) (PVP) for water microfiltration using the electrospinning method. The EPS-based nanofiber membranes exhibited a smooth morphology and were uniform in size. The concentration of the EPS/PVP solution changed some of the physical parameters of the nanofiber membrane, such as viscosity, conductivity, and surface tension. Greater viscosity and surface tension increase the nanofiber membrane diameter, whereas the addition of PVP results in hydrophilicity. Additionally, increasing the pressure increased the flux value of each variation of the nanofiber membranes. Furthermore, the rejection value was 99.99% for all variations. Finally, the use of EPS waste for nanofiber membranes is also beneficial for decreasing the amount of EPS waste in the environment and is an alternative to the current membranes available in the market for water filtration applications.

Spectroscopic investigations to reveal synergy between polystyrene waste and paraffin wax in super-hydrophobic sand

Sand based superhydrophobic materials, such as paraffin-coated sand, are the focus of global research to fight land desertification. The present work investigates the development of paraffin-coated sand with extending service life as well as improving and stabilizing hydrophobic property by adding plastic waste. While the addition of polyethylene (PE) did not improve the hydrophobic property of paraffin coated sand, incorporating 4.5% of polystyrene (PS) in the composition of coated sand increased the contact angle. Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction patterns (XRD) and two-dimensional correlation spectroscopy (2D-COS) indicated that PS increased the molecular orientation of sand and reduced the thickness of the paraffin coating. Paraffin on the other hand improved the distribution of PS and prevented aggregation with sand. Both FTIR bands at 1085 cm−1 and 462 cm−1 were more sensitive to change in PS contents, while other bands at 780 cm−1 and 798 cm−1 were more sensitive to change in paraffin contents. Moreover, the XRD patterns of sand were split into two components by the addition of PS indicating the transformation of morphology to less ordered or more distorted form. 2D-COS is a powerful tool to reveal harmony of components in mixtures, extract information related to the role of each of them, and help in decision-making process regarding choosing the appropriate recipes.

Mechanical recycling of expanded polystyrene and tire rubber waste as compatibilized and toughened blends

AbstractPackaging represents a significant source of all polymer waste produced in the world. Thus, improving recycling methods is essential to achieve an environmentally sustainable condition since the volume of produced polymer and of related waste has grown. Expanded polystyrene (EPS) foam is a thermoplastic with important performance of properties such as thermal isolation and absorption of mechanical energy that allow large application in packaging and other segments. However, the EPS recycling is a challenger due to its low density and poor properties. The rubber incorporation to the recycled EPS is an alternative for the toughening of the polymer matrix as well as improving its mechanical properties. In present study, EPS waste from electric and electronic products packaging was treated by three distinct methods for polymer densification and after it was thermo‐mechanically processed by extrusion with variable content of ground tire rubber (GTR) and compatibilizer agent styrene‐butadiene‐styrene (SBS) copolymer to produce compatibilized and toughened PS/rubber blends. Mechanical, thermal and rheological properties of materials were evaluated by different analyses. The incorporation of rubber to the recycled EPS has significantly improved the mechanical properties of the material and the presence of the SBS agent was effective to compatibilize the PS/rubber blends. Therefore, the preparation of compatibilized PS/rubber blends showed to be a way to the mechanical recycling of EPS and rubber tires waste.