Waste High-density Polyethylene Research Articles

Update to “Effect of Temperature and Vapor Residence Time on the Micropyrolysis Products of Waste High Density Polyethylene”

Update to “Effect of Temperature and Vapor Residence Time on the Micropyrolysis Products of Waste High Density Polyethylene”

A novel method for the management of sulfone-rich waste produced in the oxidative desulfurization (ODS) process

Abstract The oxidative desulfurization (ODS) process is one of the new desulfurization processes for the production of clean fuels. Despite the benefits of the ODS process, this process faces several important challenges. One of the most important challenges of this process is the management of a waste which is rich of sulfone compounds. In the present study, a new strategy which is the addition of waste to the bitumen with other solid waste such as high density polyethylene (HDPE) waste has been investigated. The experimental design method was applied to investigate the effect of addition of the sulfone and HDPE wastes to the properties of the bitumen blends including degree of penetration, softening point, and mass loss. It was found that the sulfone waste can be added to the bitumen as a softener. The results showed that several grades of bitumen including 50/60, 60/70, 85/100 can be produced through the addition of sulfone waste along with the HDPE waste to the base 60/70 bitumen. In general, the application of simple processes such as mixing the wastes with the bitumen can reduce the cost of waste management, considerably.

Thermal performance of unfired lightweight clay bricks with HDPE & PET waste plastics additives

The main objective of this study is to investigate the effect of incorporation of wastes plastics additives in the thermal performance of unfired clay bricks. The low adhesion between the clay and polymer molecules, in general, is one of the major challenges faced while blending the two components. In this paper, an innovative brick preparation technique known as the melt compounding preparation is suggested to ensure a homogenous clay-polymer dispersion and a maximum polymerization intensity inside the brick matrix. Various proportions for both polymeric, High Density Polyethylene (HDPE) & Polyethylene Terephthalate (PET), plastics wastes additives, in three grain-size are added to the earth clay. Prepared samples were tested for thermal conductivity, specific heat capacity, time lag and decrement factor properties. Collected findings showed that thermal conductivity and specific heat capacity properties improved by 40% and 55%, respectively, with the incorporation the largest polymeric-grain additives (3 mm < δ ≤ 6 mm) compared to the smallest ones (δ ≤ 1 mm). This can be explained by the high porosity produced while using larger grain-size additives. Maxwell thermal-porosity mathematical model is also used to assess the theoretically predicted thermal properties of the brick samples and compare it the experimental findings. The computed Pearson Correlation Coefficient ‘R’ is found to be very close to 1; hence, reflecting a positive association between the experimental and theoretical results. Next, a dynamic thermal inertia via a thermal simulation of a 6 m × 5 m x 2 m reference house, with variable external wall thicknesses, is executed to analyze the time lag and decrement factor of the studied brick samples. The composition of the wall is based on the experimental results of the brick samples with the optimum compressive strength, deduced from previous work, and thermal performance, in the current study. An improvement in thermal stability, with increased time lag and decreased decrement factor, is observed with larger grain size additives and thicker external walls. As a matter of fact, for a 0.3 m thick external wall made of PET based samples, the recorded time lag and decrement factor was 13.50 h and 0.148, respectively, compared to 8.99 h and 0.346 for reference values. This represents very high gains in dynamic thermal inertia properties in the range of 50% and 57% for time lag and decrement factor, respectively, compared to reference values, meaning cutting the house's energy expenses in half.

High-Precision Monitoring of Average Molecular Weight of Polyethylene Wax from Waste High-Density Polyethylene.

High-density polyethylene (HDPE) is a major component of polyethylene waste, yet only under 29.9% of waste HDPE is recycled. As an important additive, polyethylene wax (PEW) is increasingly used in many industries such as plastics, dyes, and paints. The preparation of PEW has received considerable interest because recycling and precisely controllable production can bring huge economic benefits. In this study, to recycle waste HDPE, a single screw extruder was innovatively combined with a connecting pipe to prepare PEW from the pyrolysis of waste HDPE. Using a test platform, PEWs were prepared under different pyrolysis temperatures and screw speeds, and corresponding number-average molecular weights (NAMWs) of PEWs were measured. To precisely monitor NAMW of PEW, a program was developed in MATLAB. First, the relationship between NAMW and pyrolysis ratio was obtained, and a measure-point-independence verification was conducted. Then, modified Arrhenius equations and time-dependent pyrolysis temperature were for the first time introduced into the HDPE pyrolysis model. Furthermore, the screw-speed-dependent inverse method was proposed and validated for high-precision monitoring of NAMW of PEW from the pyrolysis of waste HDPE by extrusion. PEW of desired molecular weight was able to be precisely obtained from waste HDPE.

Co-pyrolysis of sugarcane bagasse and waste high-density polyethylene: Synergistic effect and product distributions

Co-pyrolysis of sugarcane bagasse (SCB) with waste high-density polyethylene (HDPE) was performed in a fixed-bed reactor under different temperatures (400–700 °C) and blending ratios (0–100%). Product yields and chemical compositions were compared with those from the pyrolysis of individual components to ascertain the synergistic effect between SCB and HDPE. The synergistic effect of SCB and HDPE produced higher liquid yield than the theoretical value. The effect was strongest at 600 °C and 60:40 HDPE:SCB ratio, with the maximum difference of 6.02 wt%. The positive synergistic effects on the production of high-value organic compounds (alcohol, hydrocarbons, and aromatics) and inhibition of oxygenated compounds were most prominent at 600 °C and 40:60 HDPE:SCB ratio. SCB-derived hydroxyl radicals favored the secondary cracking of HDPE primary volatiles, thereby promoting the formation of aliphatic compounds with lower carbon numbers. Co-pyrolysis of SCB and HDPE also produced oil with higher carbon (34% higher) and hydrogen (47% higher) contents, and with lower oxygen content (70% lower) than those of SCB pyrolysis oil. It also achieved a high calorific value of 42.41 MJ/kg, which is comparable to those of commercial diesel fuels.

System Analyses of High-Value Chemicals and Fuels from a Waste High-Density Polyethylene Refinery. Part 2: Carbon Footprint Analysis and Regional Electricity Effects

The growing generation of plastic waste (PW) is placing severe burdens in the terrestrial and marine environments due to its inappropriate management at end of life. Governments are aware of this s...

System Analyses of High-Value Chemicals and Fuels from a Waste High-Density Polyethylene Refinery. Part 1: Conceptual Design and Techno-Economic Assessment

The increasing amount of plastic waste generation has become an important concern for the chemical industry and government agencies due to high disposal and environmental leakage rates. Chemical re...

Biodegradable hybrid polymer composite reinforced with coconut shell and sweet date seed (Phoenix dactylifera) powder: a physico-mechanical study; part A

Biodegradable hybrid composites were prepared by introducing hydrophilic organic fibres (coconut and date seed powder) into waste high-density polyethylene (WHDPE). Each hybrid polymer composite was prepared with different ratios of fibre loading of coconut shell/sweet date seed powder (5/25%, 10/25%, 15/15%, 20/10% and, 25/5%). 100% WHDPE without any filler was the control sample. The results showed that there was an increase in mechanical properties as the fibres were introduced in the WHDPE with sample 25/5% showing relatively higher superior mechanical properties due to the more crystalline densified structure of the coconut powder compared to the date seed powder. There was also a significant degree of biodegradation (de-polymerization) observed in the hybrid composites compared to WHDPE when they were exposed to the environment averaging at 1.4% per month compared to the WHDPE which averaged at 0.11% biodegradation per month. The results showed that the hybrids can be utilized for industrial and domestic applications and can also undergo biodegradation when disposed, indicating a more environmentally friendly substitute compared to WHDPE.

Three-Dimensional Printing with Waste High-Density Polyethylene

Fused filament fabrication (FFF) three-dimensional (3D) printing of semicrystalline polymers such as high-density polyethylene (HDPE) is challenging because crystallization-induced shrinkage of the...

Synthesis of Carbon Nanotubes from High-Density Polyethylene Waste

This article presents results of carbon nanotubes synthesis from household high-density polyethylene waste by thermal decomposition. A specific feature of this work is that the decomposition of high-density polyethylene waste and synthesis of carbon nanotubes were carried out in one-step using three-zone chemical vapor deposition reactor. The effect of temperature in the range of 450‒550 °C on decomposition products of high-density polyethylene was investigated. The decomposition products of polyethylene wastes were investigated by IR Fourier spectroscopy. Cenospheres obtained from ash and slag waste from thermal power plants during coal combustion were used as a catalyst for the synthesis of carbon nanotubes. The cenospheres were impregnated with an aqueous solution of iron nitrate. It was found that as a result of thermal decomposition of high-density polyethylene waste at temperature of 450 °C, gaseous carbon-containing compounds are formed, which upon further heating to 800 °C lead to the formation of carbon nanotubes with a diameter of 16‒21 nm on the surface of catalyst. Physicochemical analysis showed that turbostratic carbon is almost completely absent in the formed product. Carbon nanotubes analysis was performed by scanning electron microscopy and Raman spectroscopy.

Optimizing the usage of plastic waste in cement industry using discrete dynamic programming

Abstract Disposal of plastic waste in environment is considered to be a big problem due to its very low bio degradability and presence in large quantities. Therefore, finding alternative methods of disposing waste by using the friendly methods are becoming a major research issue. In this paper, high density polyethylene waste is mixed with cement to investigate the possibility to produce plastic cement from which we optimize its production. Our aim is to add the plastic waste at the most level so we use dynamic programming to select the company which will reduce the maximal level of plastics.

Use of Waste Polyethylene as a Source of Reducing Agent for Metal Oxide Reduction: A Case Study on NiO

This study introduces a novel way of using pyrolytic gas generated by the pyrolysis of waste high-density polyethylene (HDPE) for metal oxide reduction. A case study on NiO was carried out to reveal the feasibility of the method. Thermodynamic calculations were performed to guide and better understand the experiments. It was predicted that the pyrolytic gas mainly consisted of H2, CH4, and C6H6. HDPE pyrolysis and NiO reduction were simultaneously carried out during heating to the temperatures 550–900 K. NiO was reduced to Ni by the pyrolytic gas carried by Ar flow above 650 K. The conversion of HDPE to the pyrolytic gas increased as the temperature increased to 900 K. The extent of NiO reduction also increased with temperature due to enhanced HDPE pyrolysis. NiO reduction was completed at 900 K. It is feasible to use waste HDPE to reduce metal oxides such as NiO.

Catalytic co-pyrolysis of sugarcane bagasse and waste high-density polyethylene over faujasite-type zeolite

This study investigated the catalytic co-pyrolysis of sugarcane bagasse (SCB) and waste high-density polyethylene (HDPE) over faujasite-type zeolite derived from electric arc furnace slag (FAU-EAFS) in a fixed-bed reactor. The effects of reaction temperature, catalyst-to-feedstock ratio, and HDPE-to-SCB ratio on product fractional yields and chemical compositions were discussed. The co-pyrolysis of SCB and HDPE over FAU-EAFS increased the liquid yield and enhanced the quality of bio-oil. The maximum bio-oil (68.56 wt%) and hydrocarbon yield (74.55%) with minimum yield of oxygenated compounds (acid = 0.57% and ester = 0.67%) were achieved under the optimum experimental conditions of catalyst-to-feedstock ratio of 1:6, HDPE-to-SCB ratio of 40:60, and temperature of 500 °C. The oil produced by catalytic co-pyrolysis had higher calorific value than the oil produced by the pyrolysis of SCB alone.

Recycling of waste plastics and scalable preparation of Si/CNF/C composite as anode material for lithium-ion batteries

An economical and practical strategy is proposed for preparation of silicon/carbon nanofibers/carbon (Si/CNF/C) composite for lithium-ion batteries using self-prepared micron-sized silicon and waste high-density polyethylene (HDPE) as raw materials. The obtained Si/CNF/C composite is characterized by SEM, TGA, and XRD, as well as electrochemical characterization. Through a simple pyrolysis approach, pyrolyzed carbon and carbon nanofibers are obtained which acts as a carbon-conductive network and restrains the volumetric expansion of Si during Li-ion insertion/deinsertion processes. The obtained Si/CNF/C composite possesses high initial coulombic efficiency of 82.2% and a steady reversible capacity of 937 mAh g−1 (1685 mAh g−1 based on Si) after 100 cycles at a current density of 100 mA g−1. The strategy proposed here provides a novel way to synthesize high value-added nanocarbon materials for LIBs by reutilization of waste plastics.

Improving the Quality of Pyrolysis Oil from Co-firing High-density Polyethylene Plastic Waste and Palm Empty Fruit Bunches

This study aimed to produce and improve the quality of pyrolysis oil as a source of bioenergy that is made by mixing palm empty fruit bunch (EFB) with high-density polyethylene (HDPE) plastic waste. The slow co-pyrolysis method was employed, and HDPE waste and EFB were fed into the pyrolysis reactor at HDPE amounts of 0, 10, 25, 50, 75, and 100% by weight. The pyrolysis oil product was obtained by co-firing EFB with HDPE using the slow co-pyrolysis method in a fixed bed reactor at 500°C with a flow rate of 750 mL/min and a heating rate of 5°C/min. The chemical compositions of pyrolysis oil were analyzed by gas chromatography-mass spectroscopy. A pyrolysis oil produced by HDPE 100 wt.% was dominated by the chemical compounds of phenols, aromatics, aliphatic, and acids, while for EFB 100 wt.% was dominated with aldehydes, acids, phenols, furan and aliphatic. The addition of HDPE reduced the amount of pyrolysis oil yield, increased the pH, reduced the viscosity, and reduced the oxygen content of the pyrolysis oil. These results proved that the HDPE affected the decrease in pyrolysis oil and the increase in gas production from co-firing HDPE and EFB using the slow co-pyrolysis method.

Experimental investigation on engine characteristics fueled with waste HDPE oil and study on NO x emission variation using thermal imager.

For heavy duty applications like power generation and transportation, the best option is the compression ignition engines, but the major concerns are the rising prices and environmental issues due to the rapid depleting sources of conventional fossil fuels. The present investigation is to study the performance and emission characteristics of a single cylinder four-stroke, air-cooled direct injection diesel engine runs with an alternate fuel as waste high density polyethylene plastic oil (HDPE) obtained by catalytic pyrolysis. At constant speed, test fuels have been experimented successfully to determine the engine performance such as brake thermal efficiency, brake specific energy consumption, and exhaust gas emissions such as carbon monoxide, carbon dioxide, oxides of nitrogen, and unburned hydrocarbons. The result shows that the brake thermal efficiency is lower at all load conditions when compared to diesel fuel whereas the brake specific energy consumption decreases with increase in engine load and increases with increase in waste plastic oil blend ratio. CO emission increases and NOx emission level decreases with enhancement in engine load whereas the NOx emission and CO emission augments with increase in waste plastic oil blend percentage. But in case of NOx emission increase in concentration of waste plastic oil with diesel leads to raise in emission level. By using thermal imager, the link between in-cylinder temperature and NOx emission has been fixed. With the help of this course of action, it has been observed that in-cylinder temperature plays the major role in NOx concentration.

Proyecto Piloto Eco-rehabilitación de las instalaciones de centro ambiental y ecoturístico del nororiente amazónico

El objetivo de este estudio instaura acciones de Eco-rehabilitación en las instalaciones del Centro Ambiental y Ecoturístico de Nororiente Amazónico, efectuando tres intervenciones con el aprovechamiento de residuos plásticos, aguas lluvias y sol. El proyecto abarca desde campañas de sensibilización, recolección y transformación masiva de residuos plásticos, complementado con el aprovechamiento de aguas lluvias y energía fotovoltaica. Contribuyendo a la sostenibilidad, y promoviendo procesos de investigación, emprendimientos orientados a la preservación y conservación de los recursos naturales, para ello, se realizó la recolección junto con la comunidad, de residuos plásticos PET (polietileno tereftalato), PEAD (polietileno de alta densidad), PP (polipropileno) y ABS (acrilonitrilo butadieno estireno), para realizar procesos de recuperación y transformación mediante intrusión de plásticos, con el fin de obtener bloques en madera plástica, evaluando posteriormente propiedades mecánicas como tracción y flexión, con el fin de obtener un producto de calidad para la construcción de una Ecofachada.

Thermomechanical investigations of SiC and Al2O3–reinforced HDPE

This research work highlights the thermomechanical investigations of silicon carbide (SiC) and aluminum oxide (Al2O3)–reinforced high-density polyethylene (HDPE)–based feed stock filament of commercial fused deposition modeling (FDM) setup. The recycled HDPE waste was collected (from domestic waste) and washed with water jet for removal of contamination in the first stage. After contamination removal, rheological and thermal behavior (melt flow index, melting temperature, decomposition and enthalpy, etc.) of the unreinforced and reinforced polymer matrix was observed. The SiC and Al2O3 reinforcements in the HDPE matrix have been controlled by twin-screw extrusion process, followed by its processing on single-screw extrusion for preparation of FDM feed stock filament. The feed stock filament prepared by single-screw extruder was subjected to tensile test for mechanical properties (such as peak strength, peak load, and Young’s modulus). After ascertaining mechanical properties, multifactor optimization has been performed. Finally, scanning electron micrographs were obtained to understand the distribution of ceramic particles. This study highlights the detailed procedure for managing the polymer waste with improved mechanical properties by considering multifactor optimization. This will enhance the sustainability and also helps to develop low-cost, in-house FDM filament for possible applications as rapid tooling.

Urban mining of fuel gases via low temperature pyrolysis of post-consumer high density polyethylene wastes

Low temperature pyrolysis of high density polyethylene (HDPE) wastes was studied by adapting a cylindrical pressure cooking pot of height 30.00 cm with an internal diameter of 31.50 cm. The pyrolysis reaction was carried out with and without catalysts. The gases evolved during the pyrolysis were collected in Tedlar bags and analysis was done using a Buck 530 Gas chromatograph. Results when the pyrolysis was without catalyst, showed aliphatic hydrocarbons in the range of C 1 – C 10 with a total concentration of 87.0114 ppm and 93.9733 ppm at 200oC and 350oC respectively. The pyrolysis was repeated under catalytic influence of zeolite using catalyst/sample ratios of 1:8 and 1:16 at 150 oC and 250 oC. Results showed that the total yield of gases for HDPE under the zeolitic effect at temperatures of 150 oC and 250 oC using catalyst/sample ratio of 1:8 to be 159.4613 ppm and 394.4499 ppm respectively. The corresponding values obtained at 150 oC and 250 oC using catalyst/sample ratio of 1:16 were 595.8016 ppm and 724.0983 ppm respectively. The hydrocarbon gases revealed C 1 – C 10 aliphatic hydrocarbons which can be fractionated into fuel gases (C 1 – C 4 ), gasoline range gases (˃C 7 ) and organic solvents (C 5 – C 7 ). Keywords: Pyrolysis, high density polyethylene, zeolite, aliphatic hydrocarbon

Co-pyrolysis of biomass and plastic wastes: investigation of apparent kinetic parameters and stability of pyrolysis oils

This work is dedicated to the co-pyrolysis of real waste high density polyethylene (HDPE) and biomass (rice straw) obtained from agriculture. Mixtures of raw materials were pyrolyzed in their 0%/100%, 30%/70%, 50%/50%, 70%/30%, 100%/0% ratios using a thermograph. The atmosphere was nitrogen, and a constant heating rate was used. Based on weight loss and DTG curves, the apparent reaction kinetic parameters (e.g., activation energy) were calculated using first-order kinetic approach and Arrhenius equation. It was found that decomposition of pure plastic has approximately 280 kJ/mol activation energy, while that of was considerably less in case of biomass. Furthermore, HDPE decomposition takes by one stage, while that of biomass was three stages. The larger amount of raw materials (100 g) were also pyrolyzed in the batch rig at 550°C to obtain products for analysis focussing to their long-term application. Pyrolysis oils were investigated by Fourier transformed infrared spectroscopy and standardized methods, such as density, viscosity, boiling range determination. It was concluded, that higher plastic ratio in raw material had the advantageous effect to the pyrolysis oil long-term application. E.g., the concentration of oxygenated compounds, such as aldehydes, ketones, carboxylic acids or even phenol and its derivate could be significantly decreased, which had an advantageous effect to their corrosion property. Lower average molecular weight, viscosity, and density were measured as a function of plastic content.