Low-density Polyethylene Waste Research Articles

Catalytic pyrolysis of waste high-density (HDPE) and low-density polyethylene (LDPE) to produce liquid hydrocarbon using silica-alumina catalyst

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% wax-like hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GC-MS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. J. Bangladesh Acad. Sci. 47(2); 195-203: December 2023

Utilization of fuel energy from single-use Low-density polyethylene plastic waste on CI engine with hydrogen enrichment – An experimental study

An effective strategy to reduce global waste is to convert the waste into Energy effectively. Single-use Low-density polyethylene (LDPE) plastic waste poses an environmental challenge by slower decomposition. Pyrolysis is one of the best techniques for converting waste plastics into Waste Low-density polyethylene pyrolysis oil (WLPO), a useful energy source similar to diesel. Operating an engine directly with neat WLPO lowers the performance and increases carbon monoxide, unburnt hydrocarbons, and smoke emissions than diesel. Hence, to enhance the performance and emission characteristics of the engine operating with WLPO dual fuel mode, different flow rates of hydrogen induction from 3 to 12 lpm were studied. The results were compared with diesel and neat WLPO. 12 lpm of hydrogen induction shares 15.19 % of hydrogen energy in combustion for WLPO. Compared to neat WLPO, 12 lpm hydrogen induction has a percentage increase of 22.89 in brake thermal efficiency, 15.88 in peak pressure, 60.85 in heat release rate, and 61.46 in Nitrogen oxides, as well as a percentage decrease of 53.42 in smoke, 48.94 in carbon dioxide, 53.99 in unburnt hydrocarbons, and 86.86 in carbon monoxide. Also, these are all similar to and better than the neat diesel operation except for the NOx emission. The hydrogen induction with WLPO increases the engine performance and reduces the smoke and carbon emissions. This fuel usage with hydrogen in IC engines indirectly supports LDPE plastic waste reduction by utilization and reduces objectionable emissions.

Plastic Waste Sheets Effects on Reclaimed Asphalt Pavement Performances

Abstract This paper aims to examine physical and mechanical performances of a Reclaimed asphalt pavement (RAP) material reinforced with 5 to 15 mm size sheets of plastic waste. The three types of plastic used in the study are: low density polyethylene (LDPE), high density polyethylene (HDPE) and polyethylene terephthalate (PET) with 1%, 1.5%, and 2% dosage by weight of aggregates. Obtained Duriez test results testify to a 9% to 30% improvement in moisture resistance for all types of plastic compared to virgin mixture while for LDPE waste plastic type workability test attests an acceptable compaction condition for RAP material with less than 1.5% of waste plastic. Nevertheless, it has been noticed an increase in void index and compaction difficulties starting from 1.5% dosage, resistance to rutting has also improved with the addition of waste plastic, an improvement in fatigue strength was also observed particularly at 2% dosage.

Characterisation of new sustainable gypsum composites with low-density polyethylene waste from single-use bags

The main objective of this research is to determine the feasibility of using Low-Density Polyethylene (LDPE) waste as secondary raw material in the production of new eco-friendly gypsum composites. For this purpose, LDPE waste in crumb form has been incorporated as a partial replacement by weight of the plaster material powder at percentages of 1%, 2% and 3%. Additionally, the gypsum binder in traditional gypsum composites has been replaced for LDPE waste in granulated form, at percentages of 2.5%, 5.0% and 7.5%. The experimental campaign has involved a detailed physical and mechanical characterisation of the gypsum compounds produced to study their potential applications in the construction sector. The results show that more efficient materials are obtained with the addition of these plastic wastes, significantly reducing bulk density and thermal conductivity coefficient compared to traditional gypsum-based materials. Additionally, a considerable reduction in capillary water absorption coefficient and open porosity has been observed. Moreover, the mechanical strengths in flexion and compression surpassed the limits established by current regulations for all the prepared mixtures. In this way, these innovative gypsum composite materials can be useful for application in the production of prefabricated elements, promoting the reincorporation of these plastic wastes, which currently present a challenge from the perspective of sustainability and circular economy.

Performance, emission and combustion characteristics of liquid fuel produced through catalytic co-pyrolysis of waste LDPE and Pongamia pinnata seeds: An experimental investigation in CI engine

As there is an urgent need to address the global problem of increasing plastic waste and decreasing petroleum-based fuels, it is possible to convert waste plastic and unused biomass seeds into fuels that can be utilized in transportation sector. The current study deals with blending pure diesel (D100) with the liquid fuel (PB2) obtained from the co-pyrolysis of Pongamia pinnata seeds and waste low-density polyethylene (LDPE) with Calcium oxide (CaO) as the catalyst. Three blends of D100, namely, PB2@10 (with 10 % blend), PB2@20 (with 20 % blend) and PB2@30 (with 30 % blend) were tested for performance, emission and combustion in an unmodified CI engine for an analytical comparative analysis using standard methods. The results showed that the BSFC was almost same (0.3 kg/kWh) at higher loads for all three blends, while the BTE was found to be equal or increased compared to D100 in the range of 27–30 % at higher loads for higher blends. NOx formation was found to decrease by 19.4 % and 13 % at the highest load for PB2@30 andPB2@30. The smoke formation also decreased for all blends (maximum 22.5 %) while the maximum difference of lambda was determined to have decreased in comparison to D100, close to 1 at higher loads. The maximum cylinder pressure and temperature were also found to have increased during combustion by approximately 1 % for PB2@10 while that of PB2@20 and PB2@30 remained quite close to D100. The obtained renewable liquid fuel could certainly be utilized in blends with pure diesel for use in vehicles.

Study on optimal preparation and rheological characteristics of waste low density polyethylene (LDPE)/styrene butadiene styrene (SBS) composite modified asphalt binder

The sustainable utilization of waste low density polyethylene (LDPE) in asphalt pavements has enormous environmental and economic benefits. To enhance and benefit more from LDPE, this study deals with use of LDPE and styrene butadiene styrene (SBS) collectively for composite modification of asphalt binder. The study intends to identify the optimal blending parameters of LDPE/SBS composite modified asphalt binder by using the orthogonal experiment. The paper deals with the investigation of conventional properties and rheological properties such as Penetration, softening point, ductility, Superpave rutting parameter (G*/sinδ), failing temperature, rotational viscosity and multiple stress creep and recovery (MSCR) test parameters of the binder. Moreover, the dispersion of modifiers in asphalt binder is studied by optical microscopy. The test results point out that the optimal blending parameter for preparing LDPE/SBS composite modified asphalt is 90 min of blending at 180 °C maintaining a rate of 2500 rpm. The blending time parameter has the highest influence on the properties, with the blending temperature and blending rate having a relatively lower impact. Although, both the LDPE and SBS individually have a good impact on high temperature characteristics of asphalt binder but together as a composite, in addition to showing improved high temperature properties, they also reveal high resistance towards permanent deformation and better elastic behaviour. It is concluded that the LDPE/SBS composite modified asphalt binder performs well and is recommended better for high temperature climates. Furthermore, it is good way to enhance the application of LDPE in pavement industry and promote environmental sustainability.

Laboratory evaluation of properties of modified asphalt binder with different types of additives

This research aims to assess the properties of Polymer Modified Bitumen (PMB) binder prepared with different types of additives such as (Waste low density polyethylene (W-LDPE) and crumb rubbers (CR)and Styrene Butadiene Styrene (SBS)). Most of these additives are sustainable materials since it is derived from old scrap materials. All the above-mentioned materials (W-LDPE, CR and SBS) were added with percentages of (2, 4, and 6 percentage) of the weight of pure asphalt binder. Several tests were conducted to evaluated the properties of improved asphalt binder such as penetration test, Ductility test, Softening point test, Rotational viscosity test as well as thin-film oven test. The results of investigation revealed that, the using of different types of PMB significantly improved the physical properties and performance of asphalt. The using of sustainable waste materials such as W-LDPE and CR significantly improve the properties of PMB and contribute in recycling great amount of waste materials. Also, the results showed that the using of high percentage of SBS (6%) significantly increase the viscosity of asphalt binder and that can affect workability of Hot Mix Asphalt (HMA) compared with same percentages of W-LDPE and CR).

Biodegradation of low-density polyethylene (IDPE) by bacteria isolated from dump sites in some metropolitan cities in north central Nigeria

In this study, biodegradation of Low-Density Polyethylene (LDPE) by bacteria isolated from dump sites was evaluated in a liquid Basal Salts Medium. The bacteria, including Psuedomonas aeruginosa, Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris were isolated from soil samples taken from municipal dump sites in some metropolitan cities in North Central Nigeria, namely, Abuja, Makurdi and Jos and screened for their ability to utilize LDPE using the clear zone method. 0.500 gram waste LPDE strips (1 cm x 5 cm) were placed into a 500 milliliter flask containing sterilized liquid medium at 30 °C and incubated in a rotary shaker for eight (8) weeks. Each bacterium was added to a separate flask. Biodegradation was measured by pH changes of the media and gravimetrically by weight loss of the waste LDPE strips two weekly during the incubation period. The results obtained showed a gradual decrease in the pH of the media originally set at 7.05 with incubation time for all isolated bacteria. Psuedomonas aeruginosa and Providencia stuarti recorded the highest weight loss of the LDPE strips after eight (8) weeks at 19.80±0.04 %, with a final pH of 3.75±0.01 and 19.20±0.42 %, and final pH 4.85±0.01 respectively followed by Bacillus megaterium at 13.40±0.10% and final pH of 3.95±0.01. Klebsiella pnuemonia and Proteus vulgaris recorded the least gravimetric weight loss at 1.40±0.02 %, with a final pH of 4.75±0.01 and 0.80±0.01 %, pH 4.85±0.01 respectively. This work reveals that bacteria play a vital role in the degradation of low-density polyethylene waste in the natural environment. This can be applied to the development of commercial bioreactors in the future for the degradation of polyethylene wastes.

Optimum conditions for the biodegradation of waste low-density polyethylene strips by bacteria isolated from parts of north central Nigeria

Optimum conditions (Temperature, pH and incubation time) were studied for selected bacterial isolates Pseudomonas aeruginosa1(PA1), Pseudomonas aeruginosa2 (PA2), Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris to biodegrade low-density polyethylene (LDPE) waste by using Basal Salts Medium (BSM) containing 0.500g LDPE strips (1 cm by 5 cm each) using changes in mechanical properties and weight loss of the strips as indicators for ability of these microorganisms to degrade LDPE. The results revealed that four of the eight bacterial isolates, Pseudomonas aeruginosa1, Pseudomonas aeruginosa2, Bacillus megaterium, and Providencia stuarti showed high ability to degrade the LDPE strips after 8 weeks of incubation in liquid Basal Salts Medium at pH 6.5 -7.5 and 32oC. The tensile strength of the LDPE strips was reduced by 0.047±0.41 MN/M2 (47%) for P. aeruginosa1, 0.040±0.30 MN/M2 (40%) for P. aeruginosa2, Bacillus megaterium, 0.033±0.61 MN/M2 (33%), and Providencia stuarti, 0.027±0.41 MN/M2 (27%). The weight loss of the LDPE recorded for Pseudomonas aeruginosa1 was 19.80±0.04 %, for Pseudomonas aeruginosa2 19.40±0.08 %, 13.40±0.10 %, for Bacillus megaterium and 19.20±0.42 % for Providencia stuarti respectively. There was significant difference in the weight loss of the LDPE strips at pH 6.5 for Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis and Enterobacter hormaechei and at 30-32 oC for Pseudomonas spp., Bacillus megaterium, Klebsiella pneumonia and Proteus vulgaris(P>0.05 %).

Catalytic Pyrolysis of Waste Low-Density Polyethylene (LDPE) Carry Bags to Fuels: Experimental and Exergy Analyses

The present investigation reports the results of experiments related to the conversion of low-density polyethylene (LDPE) waste carry bags to fuel through an economic catalytic pyrolysis method in a batch reactor using zinc oxide (ZnO) as the catalyst. Plastics are highly beneficial for the day-to-day activities of human beings; however, their decomposition is limited due to their strong covalent bonding. Degradation of these big molecules into smaller ones or monomers has been attempted by several researchers in recent decades, with limited success. Pyrolysis is one of the ideas used to convert plastics, with the crowded structure of polymers, into fuel rather than small molecules. Among these plastics, LDPE is widely used as carry bags throughout the world, and, herein, the results of catalytic pyrolysis of the conversion of LDPE into fuel are reported. A compact laboratory-scale batch reactor, specially designed at our laboratory, was used to carry out the pyrolysis process. Different dosages of ZnO were used as a catalyst to carry out the pyrolysis at a specific temperature. The optimal dosage of ZnO for a 50 g waste LDPE batch was found to be 0.6 g to get the maximum oil yield. The yielded oil was analyzed chemically through Fourier transform infrared spectroscopy (FTIR) and a Reformulyzer M4 Hydrocarbon Group Type Analyzer. Evaluation of physical and chemical exergy along with exergetic efficiency of the process was carried out. The described experiments and the results represent a small but significant step toward curbing the menace of plastic solid wastes, which are degrading the environment and human life worryingly, and allowing them to be utilized for generating low-cost fuel for transportation and other applications.

Accelerated aging of polymer composite from Pennisetum purpureum fibers with recycled low-density polyethylene

The use of natural fibers (NF) as reinforcement in polymer composites have been an interesting option to improve their mechanical properties and to decrease production costs since several crops can produce large amounts of NF with low cost. This is particularly attractive for polymer waste recycling that depends of the production of cheap materials to be economically viable. Elephant grass ( Pennisetum purpureum schum) is a tropical climate plant of fast growth with high potential for production of NF. However, studies on the use of P. purpureum fibers as reinforcement in polymers, mainly for recycled polymers, have been restricted. The aims of this study was to evaluate the action of the P. purpureum fibers on the properties of composites using matrix of low-density polyethylene waste (LDPE-w) as well as to verify the behavior of recycled polymer when submitted to the accelerated photochemical aging using UVA radiation. LDPE-w and LDPE-w composite with P. purpureum fibers (LDPE-composite) were analyzed at different aging times by tensile and impact tests, melt flow rate, scanning electron microscopy and Fourier transform infrared. It was verified that P. purpureum fibers induce defects in matrix of LDPE-w, decreasing the performance of mechanical properties. Similar effect also occurs when LDPE-w is submitted to the first hours of accelerated aging. On the other hand, effects of stabilization of the degradation on the polymer matrix can be attributed to the P. purpureum fibers at high aging times. Thus, P. purpureum presents high potential for use as reinforcement in recycled thermoplastic waste.

Investigating the Use of Post-Consumer LDPE Waste and Stone Dust in Sustainable Concrete Composites

The construction industry is one of the largest producers of greenhouse gases and waste materials. One potential solution to reduce the environmental impact of construction is to use sustainable materials in the production of concrete. The effects of adding low-density polyethylene (LDPE) waste and stone dust on the mechanical properties of the 7-days cured composite materials adopting two independent categorical variables with five levels each, creating 25 groups were investigated. The dependent variables are compressive strength, tensile strength, flexural strength, and water absorption. The results show that increasing LDPE waste content and stone dust content improves the mechanical strength of the composite material but increases water absorption. The optimal combination of LDPE waste content and stone dust content is 30% LDPE waste and 40% stone dust, based on the highest values of compressive, tensile, and flexural strength and the lowest value of water absorption in the group. It also provides linear regression models and correlation analysis to determine the relationships between LDPE waste content and each dependent variable. On this basis, it suggests that LDPE waste can improve the mechanical properties of the composite material and its water resistance, but the optimal amount of LDPE waste depends on the type of material and application. The study concludes that incorporating LDPE waste and stone dust into composite materials can be a sustainable solution for waste management and the production of low-cost, high-performance materials.

Co-pyrolysis of Azadirachta indica non-edible seed and waste LDPE: Analysis of kinetic models using thermogravimetric analyser and prediction modeling with Artificial Neural Network (ANN)

Energy production from waste biomass seeds and plastic wastes must be done immediately, keeping the future in mind, as waste plastic and seeds have become a major source of attractiveness for producing liquid fuel in a pollution-free environment and disposing of waste plastic, which causes serious environmental issues. In this study, theoretical modeling was used to assess the pyrolysis feedstock potential of Azadirachta indica, or Neem non-edible seeds, and waste LDPE (low-density polyethylene) in a set ratio. Thereafter, the TG-DTG data was applied into artificial neural network (ANN). The Azadirachta indica seed-waste LDPE mixture was TG-DTG examined at three heating rates of 10, 20 and 30 °C/min. The thermodynamic parameters were also obtained at the same heating rates. A blend sample requires less energy to pyrolyze than an individual sample. When ANN prediction modeling was used to predict TG-DTG data, R2 was always found unity in training, validation, and testing, and MSE was minimised for all heating rates. Levenberg-Marquardt trained the ANN model. According to the findings of this study, combining Azadirachta indica seed with waste LDPE could be a workable alternative that would result in an improvement to the process as a whole.

Recycled plastics and rubber for green roads: The case study of devulcanized tire rubber and waste plastics compounds to enhance bitumen performance

Devulcanized rubber (DVR) and waste plastics have been studied separately as bitumen modifiers, but their individual drawbacks prevent full implementation in the field. In this paper, two pelletized composites produced by coupling DVR with waste low-density polyethylene (LDPE) and polypropylene (PP) were investigated. Linear viscoelastic properties, rutting, and fatigue cracking performance were evaluated, and results were compared to those obtained on neat and polymer-modified bitumen with high styrene-butadiene-styrene content (HiPMB). The non-recoverable creep compliance was reduced with the increasing addition of DVR with either LDPE or PP, and the modified bitumen can be classifiable as “E” grade like the common HiPMB. Bitumen modified with DVR-LDPE compounds showed the best fatigue cracking performance overall, and can fully replace the industrial HiPMB. The implications of these results go beyond the sole performance improvement since these compounds can significantly reduce the environmental impact of road construction by using two waste materials simultaneously.

Techno-Economic and Life Cycle Analyses of Thermochemical Upcycling Technologies of Low-Density Polyethylene Waste

Techno-Economic and Life Cycle Analyses of Thermochemical Upcycling Technologies of Low-Density Polyethylene Waste

Pyrolysis of waste LDPE and waste PP plastics into fuel oil in a low-cost, lab-scale pyrolyzing unit

Plastics cause severe environmental and societal issues when post-consumer plastics are discarded in the environment without proper management. Pyrolysis of plastic waste is a promising method for plastic waste management due to its valuable by-products such as fuel oil. The objective of the present study was to pyrolysis waste polypropylene (PP) and waste low-density polyethylene (LDPE) plastics into fuel oil in a low-cost, lab-scale apparatus at the maximum temperatures of 330°C and 355°C, respectively, and in turn to assess the physical properties, gross calorific value, density, kinematic viscosity, flash point, ash content, and sulfur content, of resultant fuel oil. Commercially available, recycled grades of LDPE and PP pellets, 70.0 g of each, were obtained, and pyrolysis was done in a lab-scale, low-cost batch reactor. The experiment was triplicated, and the resultant fuel oil was analyzed for physical properties by ASTM standard methods. The properties of resultant fuel oil were also compared with diesel grade criteria. Results revealed that the highest yield of fuel oil was obtained from waste PP at 79.57 wt.% while the waste LDPE resulted at 74.06 wt.% of fuel oil. No wax formation was observed in the waste PP pyrolysis process, unlike in the waste LDPE pyrolysis. The gross calorific values of waste PP and waste LDPE were 12 016 kcal/kg and 11 961 kcal/kg, respectively. It was higher than the standard value of commercial diesel. The distillation results indicated that short-chain hydrocarbon content is higher in the waste PP fuel oil sample than in the waste LDPE fuel oil sample. The results indicated that the resultant fuel oil samples were nearly closer to the diesel grade criteria. Therefore, the fuel oil produced from waste plastics is a viable alternative to traditional fossil fuels, with potential applications in power generation and transportation.

Effect of Adding LDPE Bags on Rutting and Stripping Behaviour of Asphalt Mix

Disposal or incineration of waste low-density polyethylene (LDPE) bags is a major problem, as it causes pollution. The pavement over time gets deteriorated by vehicular traffic, which mostly results in rutting and other distresses. This research is based on the performance evaluation of hot mix asphalt (HMA) modified with LDPE. Aggregates National Highway Authority Pakistan (NHA) gradation B, bitumen grade 60/70 and waste LDPE bags from the dump yards of Islamabad (Pakistan) were used in this study. Penetration, ductility and softening-point tests were conducted with bitumen modified with different contents of waste LDPE bag flakes; i.e., 0%, 2%, 4%, 6% and 8% to figure out the optimum modifier content (OMC). Marshall testing was performed for the determination of optimum bitumen content (OBC). Using OBC and incorporating LDPE contents as a replacement for OBC, HMA samples were tested for performance evaluation, including rutting resistance and moisture susceptibility and compared with the performance of unmodified HMA. It was observed that 4% of LDPE as a replacement for OBC in the HMA can be used as OMC and yielded better performance results than unmodified asphalt mix. Rutting resistance was improved by 20.86% and tensile strength ratio (TSR) for moisture susceptibility evaluation was above the specified limit of 80%. KEYWORDS: Waste LDPE bags, Low-cost bitumen modifier, Performance evaluation, Performance improvement, Cost comparison, Sustainable environment.

Conversion of waste polyolefins to polyethylene wax via pyrolysis

ABSTRACT Waste polyolefins can be converted into value-added products like oils and chemical waxes by a process called pyrolysis. In the present study, conversion of waste polyethylene to polyethylene (PE) wax was carried out via pyrolysis using a ZSM 5 (zeolite based) and Luperox as catalysts. The effect of pyrolysis residence time, catalyst type, loading on the yield, and properties of the PE wax were investigated. Further, a comparison of the properties of PE wax obtained via pyrolysis and the market sample of PE wax was made to optimize the reaction conditions of pyrolysis. It was observed that with an increase in the catalyst loading and residence time, not just the yield of PE wax reduced but it also led to the degradation in the properties of PE wax. The waxes produced via pyrolysis at residence time of 90 min for waste low-density polyethylene and 150 min for waste high-density polyethylene exhibited properties comparable to that of the market sample of PE wax. The PE wax thus obtained has application in textile coatings, plastic processing, and printing inks.

Conversion of low-density polyethylene plastic waste into valuable fuels using fly ash as a catalyst

Waste low-density polyethylene (LDPE) plastic was pyrolyzed using a batch reactor fuel oil fly ash catalyst into valuable fuels using fly ash as a catalyst.

Experimental Investigation on Pyrolysis of Domestic Plastic Wastes for Fuel Grade Hydrocarbons

Plastics usage is rising daily because of increased population, modernization, and industrialization, which produces a lot of plastic garbage. Due to their various chemical structures, long chain polymeric compositions, and thermal/decomposition behavior, it is challenging to recycle these plastic wastes into hydrocarbon fuels. In the current work, domestic plastic waste was pyrolyzed at 473 to 973 K in a fixed bed reactor and compared with the three virgin plastics LDPE (low-density polyethylene), HDPE (high-density polyethylene), and PP (polypropylene), as well as a mixture of the three (virgin mixed plastics). The pyrolysis results showed that maximum liquid hydrocarbons obtained from HDPE, LDPE, PP, mixed plastic, and domestic waste were 64.6 wt.%, 62.2 wt.%, 63.1 wt.%, 68.6 wt.%, and 64.6 wt.% at 773 K, respectively. The composition of liquid fuels was characterized using FTIR and GC-MS, which showed a wide spectrum of hydrocarbons in the C8–C20 range. Furthermore, liquid fuel characteristics such as density, viscosity, fire and flash point, pour point, and calorific value were examined using ASTM standards, and the results were found to be satisfactory. This study provides an innovative method for recycling waste plastics into economical hydrocarbon fuel for use in transportation.