Waste High-density Polyethylene Research Articles

Thermodynamics and Reduction of Bi2O3 in Waste Tire-Derived Atmosphere

The present study aimed to investigate reduction behavior of Bi2O3 in the gaseous atmosphere generated by the pyrolysis of waste tires. Thermodynamic analysis carried out in the Bi-O-C-H-S-Ar system predicted that Bi2O3 could be reduced to Bi in the temperature range 700–900 K. Bi2O3 reduction experiments were carried out as a function of reactant mass ratio ( $$ m_{\text{tire}} /m_{{{\text{Bi}}_{ 2} {\text{O}}_{ 3} }} $$ = 0–10) and temperature (600–900 K). The extent of tire pyrolysis increased as the temperature was raised to 900 K. The degree of Bi2O3 reduction increased with increasing tire pyrolysis, while the waste pyrolysis process controlled Bi2O3 reduction. The oxide reduction was incomplete, when only waste tires were used. Adding a minor amount of waste high-density polyethylene to the tires sufficed for full Bi2O3 reduction at 900 K. The reduction reactions and a model for the morphological evolution are presented. Large Bi shots formed owing to the coalescence of the liquid Bi droplets at the reduction temperature.

Thermodynamics and Synthesis of Cu Powder from CuO in Waste Tire-Derived Pyrolytic Gas Atmosphere

The present study aimed to investigate the reduction behavior of CuO particles under the gaseous atmosphere generated by waste tire pyrolysis. Thermodynamics of the reduction process indicated that CuO could be reduced to the metal via the tire (rubber) pyrolysis route in the temperature range 700–900 K. Oxide reduction experiments were conducted as a function of the reactant mass ratio (mtire/mCuO) and temperature (600–900 K). The extent of waste pyrolysis increased as the temperature was raised to 900 K. This was accompanied by an increase in the oxide reduction. A significant reduction was attained at mtire/mCuO = 1.28 when the reactants were heated to 800 K and 900 K. Adding a small amount of waste high-density polyethylene to the tire sufficed for full CuO reduction. CuO reduction reactions and morphological evolution of flower-type CuO particles to relatively equiaxed Cu particles were discussed in terms of experimental and theoretical findings.

Waste high‐density polyethylene recycling process systems for mitigating plastic pollution through a sustainable design and synthesis paradigm

AbstractThis article addresses the sustainable design and synthesis of open‐loop recycling process of waste high‐density polyethylene (HDPE) under both environmental and economic criteria. We develop by far the most comprehensive superstructure for producing monomers, aromatic mixtures, and fuels from waste HDPE. The superstructure optimization problem is then formulated as a multi‐objective mixed‐integer nonlinear fractional programming (MINFP) problem to simultaneously optimize the unit net present value (NPV) and unit life cycle environmental impacts. A tailored global optimization algorithm integrating the inexact parametric algorithm with the branch‐and‐refine algorithm is applied to efficiently solve the resulting nonconvex MINFP problem. Results show that the optimal unit NPV ranges from $107.2 to $151.3 per ton of HDPE treated. Moreover, the unit life cycle greenhouse gas emissions of the most environmentally friendly HDPE recycling process are 0.40 ton CO2‐eq per ton of HDPE treated, which is 63% of that of the most economically competitive process design.

Waste derived low cost PbO-Carbon nanocomposite and its energy storage application

Waste lead acid battery (WLAB) is possible to recycle into lead–carbon batteries (LCB) with improved performance than lead acid batteries (LAB). There is a number of research on the lead–carbon battery using PbOx-C composite. This will develop a sustainable economics of WLAB as well as its environmental concerns, achieving UN SDG goal number 12 for sustainable consumption and production. In this study, lead oxide (PbO) and PbO-carbon composite were prepared using waste lead acid battery and waste high density polyethylene (HDPE) plastic. Leaching process was adopted for preparation of PbO nanoparticle from waste lead acid battery electrode. Initially, waste lead acid battery paste was converted to lead citrate and was calcined at 400 ℃ for 60 min to convert PbO nanoparticle. The band gap of PbO nano is found to be 4.17 eV using Tauc plot from UV–vis spectroscopic data. The XRD data shows a massicot phase of PbO nanoparticle of size 62 nm. PbO-Carbon composite was prepared using pyrolysis technique at 600 °C taking 1:2 ratio of waste HDPE plastic and PbO NP. The band gap of prepared PbO-Carbon composite is found to be 4.0 eV. The Pt electrode was modified by PbO-carbon composite by casting and drying method using PVDF as a binder to electrode. The capacitance, energy density of the PbO-C nanocomposite modified electrode are found to be 115.33 F/g and 70.63 Wh/kg for scan rate of 0.1 V/s, respectively. The presented study suggests an economically viable process to derive value added products from waste plastic and waste lead acid batteries, to be useful for energy storage application in the form of lead–carbon battery with improved performance than lead-acid battery.

Pyrolysis of waste polyethylene under vacuum using zinc oxide

ABSTRACT Innovative approaches in pyrolysis process to recover energy from plastic wastes in a sustainable manner are being explored progressively. Present study reports the effect of vacuum on pyrolysis of polyethylene waste in the presence of zinc oxide as a catalyst. Firstly, the effect of vacuum on the pyrolysis of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) wastes was investigated by conducting the pyrolysis at various applied vacuums of 101.325 kPa, 88 kPa, 73 kPa, 60 kPa, and 47 kPa in the absence of catalyst. Vacuum was observed to have positive effect on the pyrolysis in terms of increase in the yield of liquid product. Further, the effect of zinc oxide on the pyrolysis was studied by performing the pyrolysis at various catalyst feed ratios of 3:100, 5:100, 10:100 and 15:100 under the applied vacuum of 50 kPa. The maximum yield of liquid product obtained was 74.58% and 78.65% for the waste LDPE and HDPE, respectively, for the catalyst feed ratio of 15:100 and at applied vacuum of 50 kPa. GC-MS analysis of the liquid products demonstrated that the major fraction of hydrocarbons present is in a sufficiently narrow range. The fuel properties of the obtained liquid product were also determined.

Formulation of modified bitumen emulsions from polymer wastes and used motor oil

Abstract Wastes made from used high density polyethylene (HDPE), scrap tyres, and waste oil imparted to a significant number of total waste disposal into environment. The materials exhibit detrimental effects on local environment if not properly disposed or repurposed. The study was conducted to formulate these wastes into a modifier and compatibilising agent for the modified bitumen. The process involved heating and mixing of a predetermined ratio of the wastes, neat bitumen and crude oil. About 20 wt% of neat bitumen, and pre-determined ratios of HDPE waste, crumb rubber, crude oil, and used motor oil were used in the study for the formulation. The modified bitumen was further tested for the softening point and the penetration tests to evaluate the properties of the formulated bitumen. The modified bitumen was further processed into emulsified bitumen with the addition of polyethylenimine, 80% ethoxylated solution which is the novelty of this work. The result shows that the modified bitumen has the softening point of 33.85 and 41.70 ℃, and the penetration value of 386.8 and 383 (1/10 mm) for Formulation 1 and Formulation 2, respectively. The best ratio of 20:2:39:39 (bitumen: HDPE: crude oil: used oil) was used for the emulsification process.

PE-contaminated industrial waste ground tire rubber: How to transform a handicapped resource to a valuable one

Sustainability and enhancement of recycling differing polymer waste has become a leading driver for industries associated with this type of waste. However, polymer waste streams that have not seen as ‘typical’ have existed in smaller but not insignificant amounts. This study has focused on the recycling of such a waste resource that is not classified as a typical one in developed countries but appears in other locations globally where opportunities for careful waste pretreatment are hindered, therefore creating a challenge for waste handling and the application of modern techniques. Compatibilizing is a strategy employed to recycle ground tire rubber (GTR) by blending with waste high density polyethylene (w-HDPE). Such processing methods and measurement techniques have been chosen to allow easy access without extra costs. For enhanced incorporation of the filler into the matrix olefin-maleic-anhydride copolymer based additives have been synthesized and have succeeded in creating a more homogenous blend with samples having a good surface appearance and mechanical properties. Outstanding Charpy impact strength at room temperature (10.1 kJ/m2) has been achieved in compatibilized 70/30 w-HDPE/GTR (containing 20% PE-contaminant), while elongation at break and tensile strength have been 10.3% and 14.9 MPa. Morphological structure of rubber resources and blends have been assessed by SEM while analytical properties and other features of experimental compatibilizing additives have been studied by e.g. FT-IR.

Thermal Decomposition Kinetics of Basalt Fiber-Reinforced Wood Polymer Composites.

Thermogravimetric analysis (TGA) was used for the observation of the pyrolysis kinetics characteristics of high density polyethylene (HDPE)-based composites enhanced by a variety of basalt fibers (BFs) and wood flour (WF). The improved Coats-Redfern (C-R), Flynn-Wall-Ozawa (F-W-O), Friedman, and Kissinger methods were utilized to ascertain the specific apparent activation energy (Ea) of each component and composite material. The results indicate that BFs do not decompose under 800 °C, while the pyrolysis of WF and waste HDPE showed two significant weight loss zones (250–380 °C and 430–530 °C), relative to cellulose/hemicellulose and HDPE thermal degradation, respectively. The average Ea of WF/BF/HDPE composites over the entire pyrolysis process obtained by the modified C-R method fluctuated in a range of 145–204 kJ/mol and increased with the BF content, which was higher than that of WPC (115–171 kJ/mol). The value of Ea computed by the F-W-O method was significantly lower than that computed with the improved C-R method, which could validate the reliability of two methods by comparing with the literature. The Friedman and Kissinger methods were not applicable to this composite material reinforced by mixed fillers, so the obtained Ea values were quite different from the previous two methods. The changes in Ea showed that the addition of BFs could improve the average Ea and further enhance the thermal stability and flame resistance of the composites.

Assessment of Mechanical Properties of Recycled HDPE and LDPE Plastic Wastes

Most plastic materials can be recycled, and turning them into some useful products can be one of the options in reducing environmental pollutions. In this project, High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) were used, shredded into smaller pieces and were hot-pressed to become flat plates. Both materials were then mixed with industrial waste sawdust with an aim to investigate their material properties and their suitability to be used in domestic applications such as bricks, pavement and roof tiles. Three destructive and one non-destructive methods have been conducted: tensile, impact, water absorption and ultrasonic testing. It was found that the tensile properties and impact resistance of the recycled HDPE are better than the recycled LDPE, but 10% lower than their virgin polymers. Higher stiffness and lower impact resistance were observed from specimens with additional sawdust filler in comparison to their original polymers. From the ultrasonic measurement, higher wave velocity and lower attenuation in HDPE specimens were observed, compared to the LDPE specimens, attributed by a higher modulus and density of the HDPE specimens. The ultrasonic velocity, which reflects the elastic modulus, and the attenuation that reflect the microstructure inhomogeneity are respectively decreased and increased when more fillers were added to the original specimens. This study reveals that the mechanical properties of the recycled HDPE and LDPE are closer to their virgin materials, and they have huge potential for plastic recycling.

DESIGN AND PROPERTIES OF COMPOSITE SUSTAINABLE BUILDING MATERIAL BY USING WASTE HDPE

The aim of this study is to produce next generation of sustainable building materials by using wood veneers and waste plastics. In this study, plywood was produced using poplar (Populus Euphratica) veneer and waste high-density polyethylene (HDPE). Four different high-density polyethylene amounts were used (170 g/m², 200 g/m², 240 g/m² and 280 g/m²). Some technological properties such as density, modulus of elasticity (MOE), modulus of rupture (MOR), and impact bending (IB) were investigated according to Turkish standards TS EN 323, TS EN 310, TS EN 310 and TS 2477, respectively. According to obtained data, the density, MOR, MOE and IB values are increased by increasing the usage rate of HDPE in composite production.

Study on HDPE Effect on Rutting Resistance of Binder

Literature has shown positive results to using waste plastic as an alternative source for PMBs where considerable interest in using waste High-density polyethylene (HDPE) has been highlighted on improving rutting resistance. Most importantly, using a waste polymer for an application has benefits (i.e., maintenance, environmental) by improving the durability and quality of our roads and by avoiding polymers from landfill or incineration. This research uses the Multiple Stress Creep Recovery (MSCR) test to assess the performance of a binder modified with waste HDPE polymer. The outcomes of this research highlights that a HDPE content of 2–4% shows a substantial increase in rutting resistance and an improvement in elastic recovery. The elastic recovery reported does improve from previous research results however it does underperform in comparison with the Styrene butadiene styrene (SBS) polymer counterpart. Furthermore, it can be indicated by the aging index that a HDPE content of greater than 4% can be detrimental to the aging effects leading to fatigue cracking. It is recommended that a combination of both waste HDPE and an elastomeric polymer such as crumb rubber is to be used in future test work to improve the elastic recovery and address the effects of fatigue cracking.

Sustainable Design and Synthesis of Waste High-Density Polyethylene Recycling Process

Sustainable Design and Synthesis of Waste High-Density Polyethylene Recycling Process

Emission profiling of a common rail direct injection diesel engine fueled with hydrocarbon fuel extracted from waste high density polyethylene as a partial replacement for diesel with some modifications

A hydrocarbon fuel extracted from waste high-density polyethylene (WHDPE) by catalytic pyrolysis in a batch scale reactor is blended with diesel by 30% vol. (called as D70H30) is tested in a variable compression ratio engine equipped with a common rail system. Experiments were conducted at three compression ratios (16:1, 17.5:1, and 19:1) and exhaust gas re-circulation (EGR) rates (0%, 10%, and 20%) at the engine’s rated power to evaluate its combustion, performance and emission characteristics. The results revealed that, increasing the compression ratio resulted in higher peak cylinder pressure (PCP) and heat release rates (HRR). Introduction of EGR diminished both PCP and HRR peaks. The brake thermal efficiency of D70H30 blend was 4% lower than diesel at same operating conditions which got better at higher compression ratio without EGR. NOx emission was highest when injected at compression ratio 19:1 and at 0% EGR rate which was 6% and 3% higher than diesel and D70H30 blend operated at engine stock settings. In comparison with baseline diesel smoke opacity remained lower at all operating conditions, where lowest smoke emission was recorded at CR19 and at 0% EGR rate. UHC and CO emission followed the similar trend of smoke opacity. Whereas CO2 emission increased with compression ratio and reduced with induction of EGR. It can be concluded from the study that at higher compression ratio and low EGR rates D70H30 blend can be effectively utilized in a CRDi engine.

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...