Solid Plastics Research Articles

Evaluating coastal lagoon sustainability through the driver-pressure-state-impact-response approach: a study of Khenifiss Lagoon, southern Morocco

Coastal lagoons are valuable ecosystems, providing socioeconomic benefits and supporting human populations and biodiversity. However, these systems face several challenges, making them vulnerable to both natural and human factors. In this study, we apply the Driver-Pressure-State-Impact-Response (DPSIR) Approach to conduct a comprehensive socioeconomic and environmental assessment of the Khenifiss Lagoon to promote sustainable development and support decision-makers. Located on the southern Atlantic coast of Morocco, the lagoon was designated a natural reserve in 1962, a biological reserve in 1983, and a protected wetland under the Ramsar Convention since 1980. This study represents the initial endeavor to conduct a comprehensive global and multidisciplinary environmental assessment of the lagoon by using a wide range of data sources, including relevant publications and reports, satellite images and remote sensing data, field observations, and interviews, all analyzed under the DPSIR framework. Our findings show that both natural and human factors have an impact on the ecosystem. Natural Factors associated with the geomorphological features of the region likely contribute to the silting of the lagoon, possibly intensified by a large shipwreck stuck at its inlet. Meanwhile, human factors encompass population growth (at a rate of 2% per year), tourism, shellfish farming, fishing, shellfish harvesting, and salt extraction. Our results reveal significant changes in the lagoon’s condition in recent years, including a reduction in water body extent, a probable decrease in depth, and an increase in the accumulation of solid waste, plastics, and wastewater in three sectors spanning a total surface area of 464 ha (equivalent to 7% of the lagoon), a substantial expansion of the salt mining area encompassing 368 ha, and a remarkable loss of biodiversity, manifested in declining fish stocks and seabird populations. This study showed that the lagoon is positioned as a potential site for economic growth and serves to alert stakeholders and the local population to the ecosystem’s environmental issues. Based on the findings of this study, we highly recommend regulating human activities within the lagoon, the removal of the wreck at the entrance, proper waste management, community awareness programs, and strict monitoring and enforcement of regulations to protect the environment.

Microplastics and nanoplastics released from injection syringe, solid and liquid dimethylpolysiloxane (PDMS)

For a plastic syringe, a stopper at the end of plunger is usually made of polydimethylsiloxane (PDMS, and co-ingredients). To reduce friction and prevent leakage between the stopper and barrel, short chain polymer of liquid PDMS is also used as lubricant. Consequently, an injection process can release solid PDMS debris from the stopper and barrel, and liquid PDMS droplets from the lubricant, both of which are confirmed herein as solid and liquid micro(nano)plastics. From molecular spectrum perspective to directly visualise those micro(nano)plastics, Raman imaging was employed to analyse hundreds-to-thousands of spectra (hyper spectrum or hyperspectral matrix) and significantly enhance signal-to-noise ratio. From morphology perspective to provide high resolution of image, scanning electron microscopy (SEM) was engaged to cross-check with Raman images and increase assignment / quantification certainty. The weak Raman imaging signal of nanoplastics was extracted using image deconvolution algorithm to remove the background noise and average the signal variation. To increase the result’s representativeness and avoid quantification bias, multiple syringes were tested and multiple areas were randomly scanned toward statistical results. It was estimated that thousands of microplastics and millions of nanoplastics of solid/liquid PDMS might be injected when using a plastic syringe of 1 mL. Overall, Raman imaging (along with algorithm and SEM) can be helpful for further research on micro(nano)plastics, and it should be cautious to use plastic syringe due to the increasing concern on the emerging contamination of not only solid but also liquid micro(nano)plastics.

Green direct ultrasonic slurry sampling and electrothermal atomic absorption spectrometry method for metal analysis of solid plastics samples.

This work presents a "green" analytical method developed for the determination of potentially toxic metals such as aluminium, barium and chromium in solid plastics samples using the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry. The development of the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry entailed optimisation of the measuring conditions, which included optimisation of the temperature programme, selection of an appropriate liquid medium for slurry preparation, optimisation of the concentration and volume of the liquid medium and optimisation of the mass of the solid plastics sample. The following conditions were determined: the optimal pyrolysis temperature for aluminium, barium and chromium was in the range of 1300 °C to 1700 °C and the optimal atomisation temperature was in the range of 2100 °C to 2400 °C. The optimal liquid media for solid plastics samples were H2O, 0.2% (v/v) HNO3 and 0.2% (v/v) HCl. The optimal volume of liquid medium was in the range from 5 to 15 mL and the mass of the solid plastics samples was in the range from 30 to 100 mg. The limit of detection and limit of quantification were estimated as 0.06-0.52 ng g-1 and 0.22-1.69 ng g-1 for aluminium, 0.11-0.94 ng g-1 and 0.37-3.14 ng g-1 for barium and 0.07-0.31 ng g-1 and 0.25-1.04 ng g-1 for chromium. Relative standard deviation was below 5% for all plastic samples analysed. Based on the established validation parameters, the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry represents a viable technique for metal analysis of a variety of plastic materials. The concentrations of analytes in individual solid plastic samples were in the range of 1.36 ± 0.06 μg g-1 to 22.65 ± 0.66 μg g-1 for aluminium, 1.13 ± 0.03 μg g-1 to 6.01 ± 0.22 μg g-1 for barium and 0.60 ± 0.03 μg g-1 to 10.48 ± 0.46 μg g-1 for chromium.

Solvent‐Free Depolymerization of Plastic Waste Enabled by Plastic‐Catalyst Interfacial Engineering

AbstractDepolymerization of condensation polymers by chemolysis often suffers from the large usage of solvents and homogeneous catalysts such as acids, bases, and metal salts. The catalytic efficiency of heterogeneous catalysts is largely constrained by the poor interfacial contact between solid catalysts and solid plastics below melting points. We report here our discovery of autogenous heterogeneous catalyst layer on polyethylene terephthalate surfaces during the generally believed homogeneous catalytic depolymerization process. Inspired by the “contact mass” concept in industrial chlorosilane production, we further demonstrate that the construction of plastic‐catalyst solid‐solid interfaces enables solvent‐free depolymerization of polyethylene terephthalate by vapor phase methanolysis at relatively low temperatures. Trace amounts of earth‐abundant element (zinc) introduced by electrostatic adsorption is sufficient for catalyzing the depolymerization. The concept of plastic‐catalyst contact mass interfacial catalysis might inspire new pathways for tackling plastic waste problems.

Solvent-Free Depolymerization of Plastic Waste Enabled by Plastic-Catalyst Interfacial Engineering.

Depolymerization of condensation polymers by chemolysis often suffers from the large usage of solvents and homogeneous catalysts such as acids, bases, and metal salts. The catalytic efficiency of heterogeneous catalysts is largely constrained by the poor interfacial contact between solid catalysts and solid plastics below melting points. We report here our discovery of autogenous heterogeneous catalyst layer on polyethylene terephthalate surfaces during the generally believed homogeneous catalytic depolymerization process. Inspired by the "contact mass" concept in industrial chlorosilane production, we further demonstrate that the construction of plastic-catalyst solid-solid interfaces enables solvent-free depolymerization of polyethylene terephthalate by vapor phase methanolysis at relatively low temperatures. Trace amounts of earth-abundant element (zinc) introduced by electrostatic adsorption is sufficient for catalyzing the depolymerization. The concept of plastic-catalyst contact mass interfacial catalysis might inspire new pathways for tackling plastic waste problems.

Performance evaluation and conservation of waste solid plastics into alternative fuel for a pollution‐free environment

AbstractThe handling of waste plastics is a big challenge and various recycling routes are imposed to prevent the environmental ecosystem. Waste plastics are one of the major pollutants in the living environment and have characteristics such as non‐dehydration and toxicity. The wastages are occupying natural lands and water source areas, decreasing the soil behavior, reducing the minerals, and affecting the environmental ecosystem. In this situation, waste plastics are effectively handled with a suitable recycling process that helps to minimize toxicity. According to the present research, waste plastics are handled by separate arrangements and treated with the pyrolysis technique to obtain useful alternative fuel oil for automotive fuel applications. The synthesized pyrolysis (waste plastic oil fuel) oil fuel is tested by single stage four‐stroke diesel engines and its performance is compared with standard diesel fuel. The test results show that the brake thermal efficiency is improved by 28.85%. A higher 37% yield was obtained during this decomposition process above the 550°C temperature of 1 kg of waste plastics, formed as gas and condensed via cooling water, maintaining an ambient temperature. Moreover, the DI gas emission analyzer is used to evaluate the exhaust gas emission result found less than 1% of the CO and HC formation.

Development and characterization of polyvinyl chloride/poly lactic acid blend based biodegradable polymeric films

The present work aimed to decrease the environmental contamination, which is caused by solid non-degradable plastics waste. To overcome this serious global concern, the development, and characterization of a bio-degradable film by blending different proportions of the natural polymers poly lactic acid (PLA) to the conventional petroleum polymer has been done. In this process, PLA was synthesized in the lab by condensation method and polyvinyl chloride (PVC)/PLA blends film was developed by solution casting method with and without adding compatibilizer as poly methyl methacrylate (PMMA). The large domain size and two separate glass transition temperatures in the results indicated an immiscible blend form without a compatibilizer. The film developed with 30% PLA blended with PVC showed the highest biodegradability and it was observed that approximately 50% of the film was degraded in 8 months. The shelf lives of tomatoes stored under PVC-PLA blended film were found to be 21 days at ambient temperature (25 °C) with preserved quality attributes.

The Strength Properties Of Adhesive Joints Used In The Creation Of Plastic Model Kits Evaluation

The article presents information on model plastics presented on the market of the Republic of Belarus. The analysis of methods for creating accurate model sets using both 3D printing from thread and granules, and obtaining model sets from an array of model plastic using 3D milling is carried out. The properties were evaluated and the behavior of glued and solid plastics under compressive loads in the longitudinal and transverse directions was shown. Economic efficiency assessment of various methods of obtaining model sets is given, based on a comparison of the cost of materials and the production process itself.

Microbial Destruction of Polypropylene and Polyvinylchloride Samples under the Anaerobic Conditions

Abstract—The most advantageous characteristic of the materials made of synthetic polymers, such as their resistance to biodegradation, is simultaneously the reason for their accumulation and environmental pollution. Nevertheless, some type of plastics under aerobic conditions undergo slow microbial degradation, however, there is lack of information on the anaerobic degradation of plastics. In this work, we studied the growth of anaerobic moderately thermophilic (55°C) consortiums in the presence of samples made of polypropylene (PP) and polyvinyl chloride (PVC). It was shown that the microbial biomass increased compared to the control, as well as anaerobic decomposition products (CO2, H2, and H2S) were detected, and the total weight of the plastics decreased by 4.4% (PP) and 6.5% (PVC) compared to the control. Bacterial cells adhere and form colonies and biofilms on the surface of the plastic materials. An analysis of the composition of microbial communities showed an increased number of anaerobic hydrolytics of the genus Tepidimicrobium, potential syntrophic bacteria of the genus Tepidanaerobacter, and especially sulfate-reducing bacteria (Desulfohalotomaculum). With help of differential scanning calorimetry and Fourier spectroscopy it was revealed that the decrease in the mass of plastic mainly occurred due to the hydrolysis of additives (plasticizers). The role of such microbial communities in the aquatic environment and anaerobic layers of the municipal solid waste landfills, where PP and PVC plastics can be destructed under the elevated temperatures of anaerobic conditions, is discussed.

How to Make Personal Protective Equipment Spontaneously and Continuously Antimicrobial (Incorporating Oxidase-like Catalysts).

The inability of commercial personal protective equipment (PPE) to inactivate microbes in the droplets/aerosols they intercept makes used PPE a potential source of cross-contamination. To make PPE spontaneously and continuously antimicrobial, we incorporate PPE with oxidase-like catalysts, which efficiently convert O2 into reactive oxygen species (ROS) without requiring any externally applied stimulus. Using a single-atom catalyst (SAC) nanoparticle containing atomically dispersed copper atoms as the reactive centers (Cu-SAC) and a silver-palladium bimetallic alloy nanoparticle (AgPd0.38) as models for oxidase-like catalysts, we show that the incorporation of oxidase-like catalysts enables PPE to inactivate bacteria in the droplets/aerosols they intercept without requiring any externally applied stimulus. Notably, this approach works both for PPE that are fibrous and woven such as a commercial KN95 facial respirator and for those made of solid plastics such as an apron. This work suggests a feasible and global approach for preventing PPE from spreading infectious diseases.

High-yield H2 production from polypropylene through pyrolysis-catalytic reforming over activated carbon based nickel catalyst

With the aggravation of energy crisis and environmental pollution, green and renewable new alternative energy has become the focus of global attention. Hydrogen energy has become an important part of the global energy pattern in the future. Conversion of solid waste plastics into hydrogen energy by pyrolysis/gasification is a promising solution. This study aims to explore a method of high-yield in hydrogen by breaking down polypropylene, a cheap and efficient nickel catalyst is prepared and applied to the experimental study of hydrogen production by pyrolysis-catalytic reforming. The effects of catalytic temperature, Ni loading (%) and catalyst addition amount on hydrogen production of catalyst were investigated, the hydrogen production was increased by introducing water vapor. Under the optimized reaction parameters (catalytic temperature 900 °C, PP to catalyst ratio 1:0.75, Ni loading 15 wt%), the hydrogen yield is up to 40.24 mmol/gPP without water and 134.91 mmol/gPP with water, the addition of water significantly increased hydrogen production. this results have obvious advantages in hydrogen production compared with similar studies. Furthermore, the existence of various forms (snake-like, straight carbon nanotubes and carbon nanospheres) of carbon deposition found in this paper can provide new ideas for researchers working on graphite carbon. This study provides an effective new approaches for enhancing hydrogen production by pyrolysis/gasification of waste plastics.

Dioxin Formation in Biomass Gasification: A Review

The amount of PCDD/F emissions produced by gasification operations is often within standard limits set by national and international laws (<0.1 ng TEQ/Nm3). However, a recent assessment of the literature indicates that gasification cannot always reduce PCDD/Fs emissions to acceptable levels, and thus a common belief on the replacement of incineration with gasification in order to reduce PCDD/Fs emissions seems overly simplistic. A review that summarizes the evidence on when gasification would likely result in environmentally benign emissions with PCDD/F below legal limits, and when not, would be of scientific and practical interest. Moreover, there are no reviews on dioxin formation in gasification. This review discusses the available data on the levels of dioxins formed by gasifying different waste streams, such as municipal solid wastes, plastics, wood waste, animal manure, and sewage sludge, from the existing experimental work. The PCDD/Fs formation in gasification and the operational parameters that can be controlled during the process to minimize PCDD/Fs formation are reviewed.

A waste to energy approach for the effective conversion of solid waste plastics into graphene nanosheets using different catalysts for high performance supercapacitors: a comparative study

Conversion of plastic waste into graphene nanosheets and its application in supercapacitor.

Gasoline like fuel from plastic waste pyrolysis and hydrotreatment

Recycling of plastic waste is desirable to lower environmental pollution and fulfil the requirements of circular economy. Energetic utilization is another possibility, however, municipal solid waste containing plastics is usually combusted to generate heat and electricity. An attractive way of dealing with plastic waste is pyrolysis, which has the potential of producing liquid hydrocarbons suitable as a transportation fuel. The pyrolysis results of three plastics produced in the largest amount globally, namely polyethylene, polypropylene and polystyrene as well as their mixtures are presented. The experiments were performed in a laboratory scale batch reactor. The pyrolysis oils were further processed by distillation to provide gasoline and diesel like (distillation cuts at 210 and 350 °C) hydrocarbons. The gasoline fractions were analysed by GC-MS and the composition was compared with the EU gasoline standard. It was found that the oils from PE, PP and PS contain compounds present in standard gasoline. Mixing PS with PE and PP before the pyrolysis, or the oils afterward produces much closer results to standard requirements as PS pyrolysis generates mostly aromatic content. As standard maximizes the olefin content of gasoline to 18 Vol%, hydrogenation was also performed using Pd based catalyst. The hydrogenation process significantly reduced the number of double bonds resulting in low olefin content. Results show that the pyrolysis of plastic waste mixtures containing PE, PP and PS is a viable method to produce pyrolysis oil suitable for gasoline-like fuel extraction and further hydrogenation of the product can provide gasoline fuels with low olefin content.

Use of dirty plastic waste as precursors for activated carbon production—A contribution to the circular economy

AbstractThe production of activated carbons (ACs) from dirty plastic wastes derived from the mechanical/biological treatment of urban solid wastes, disposable plastics and plastics used in agriculture is reported. The use of these precursors is innovative and contributes to the circular economy by the valorization of dirty plastics that are usually disposed in landfills. ACs were produced by physical activation, with air or CO2, and chemical activation, with KOH or K2CO3. ACs presented a BET (N2) area and pore volume up to 723 m2/g and 0.32 cm3/g. Selected samples were tested for the 2,4‐dichlorophenoxyacetic acid (MCPA) and 4‐chloro‐2‐methyl‐phenoxyacetic acid (2,4‐D) removal from the liquid phase. PB‐K2CO3‐1:1–700 presented an apparent maximum adsorption capacity of 245 and 289 mg g−1 for MCPA and 2,4‐D, respectively.

Estimating Polymer Properties and Practicing Statistical Tools in Undergraduate Level through Simple Experiments

This paper presents a practical laboratory approach on polymer melt flow rate and stress-strain testing to teach undergraduate students how to measure important properties of molten and solid plastics. They may learn how to obtain parameters that are important for: quality control; processing; engineering design on polymer and petrochemical industries; and even in materials selection for engineering applications. Starting from a database obtained from this traditional practice, statistical tools for data analysis were applied. Four different grades of commercial polypropylene were studied, and the 95 % confidence intervals of different parameters were compared with the suppliers’ catalogue data. This pedagogical approach aims to add a statistical point of view to laboratory experiments and to complement the learning.

Study of Analysis Method on Microplastic Identification in Bottled Drinking Water

AbstractMicroplastic has attracted the attention of the scientific community since the last 3 years due to its effects and damages to the environment. Microplastics are defined as tiny solid plastics generally ranging from 20 µm to 5 mm in diameter. They are roughly classified into small (20 µm–1 mm) and large (1–5 mm) microplastics. In this study two preparation methods to analyze the presence of microplastics in bottled drinking water are developed. Microplastic in drinking water is isolated by direct filtration and drying methods. By drying method, the isolated material is then analyzed using Fourier‐transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) instrument. Since the isolated material from filtration method is observed by digital microscope and further analyzed using FTIR microscope. FTIR microscope has been used to identify the type of plastic material. The small size of a particle starting at 20 microns can be identified using this instrument. Microplastics, high density polyethylene, and polyethylene terephthalate, size 20–200 µm are spiked in drinking water as control. The observation of the filtrates shows that microplastic only appeared in drinking water that has been spiked with microplastic. Further plastic identification using FTIR spectroscopy, DSC, and TGA needs microplastic in large amount.

Thermophilic whole-cell degradation of polyethylene terephthalate using engineered Clostridium thermocellum.

SummaryPolyethylene terephthalate (PET) is a mass‐produced synthetic polyester contributing remarkably to the accumulation of solid plastics waste and plastics pollution in the natural environments. Recently, bioremediation of plastics waste using engineered enzymes has emerged as an eco‐friendly alternative approach for the future plastic circular economy. Here we genetically engineered a thermophilic anaerobic bacterium, Clostridium thermocellum, to enable the secretory expression of a thermophilic cutinase (LCC), which was originally isolated from a plant compost metagenome and can degrade PET at up to 70°C. This engineered whole‐cell biocatalyst allowed a simultaneous high‐level expression of LCC and conspicuous degradation of commercial PET films at 60°C. After 14 days incubation of a batch culture, more than 60% of the initial mass of a PET film (approximately 50 mg) was converted into soluble monomer feedstocks, indicating a markedly higher degradation performance than previously reported whole‐cell‐based PET biodegradation systems using mesophilic bacteria or microalgae. Our findings provide clear evidence that, compared to mesophilic species, thermophilic microbes are a more promising synthetic microbial chassis for developing future biodegradation processes of PET waste.

Experimental investigation to identify the type of waste plastic pyrolysis oil suitable for conversion to diesel engine fuel

Plastics for various applications is increasing every year due to outstanding advantages, but after use recycling and disposal have remained a challenge. In this paper, through experiments, we compare properties of pyrolysis oil derived from after use HDPE (High-density polyethylene), LDPE (Low-density polyethylene), PP (Polypropylene)and styrene for their suitability as diesel engine fuel. This experimental study is to identify which type of plastic is suitable for blending with diesel. The physicochemical properties of pyrolysis oil of HDPE, LDPE, PP, and styrene were tested, tabulated and compared with diesel. The physicochemical properties of polypropylene pyrolysis oil (PPO) were found to be superior to the produced pyrolysis oil of HDPE, LDPE, and styrene. The GC-MS(Gas chromatography-mass spectrometry)and FT-IR (Fourier transform-infrared spectroscopy) were taken for pyrolysis oil of HDPE, LDPE, PP, and styrene and compared with diesel. PPO showed lower carbon number chain compounds compared to the other three waste plastics. We selected PPO for diesel engine performance and emission trials based on the results of the above tests. PPO was blended in the ratios of 5%, 10% and 15% with diesel. Combustion analysis showed a increase in cylinder pressure in comparison to diesel values. The heat release rates (HRR) were sharply higher than diesel. Both cylinder pressure and HRRvalues for PPO increased as the blend ratios increased. The emission results showed an increase in carbon monoxide (CO), hydrocarbon (HC)and oxides of Nitrogen (NO x )emissions. The multiple times increase in emissions is due to the presence of unsaturated hydrocarbons and higher carbon number of saturated compounds in PPO. GC-MS tests confirmed the presence of such compounds in PPO. To reduce the unsaturation to negligible levels, we will take up future experiments in hydrogenating PPO with various catalysts and test the performance and emissions in diesel engines. The experiment and analysis plan for conversion of solid waste plastics to diesel fuel. • Four types of plastics selected to determine which plastic has a diesel like quality. • Physicochemical properties, FTIR, GCMS results showed Polypropylene had diesel like qualities. • Diesel Engine trials done with polypropylene pyrolysis oil blended with diesel as fuel. • Engine trial results showed delayed combustion, high heat release rate and higher emission.

Kerosene Like Fuel Characteristics from Municipal Solid Plastics Waste Pyrolytic Oil for Domestic Purposes

The aims of the research are to characterized pyrolytic oil as fuel and utilize it for heating purpose. The pyrolytic oil was characterized to decide whether this oil can be used as fuel for the desired application or not. The highest pyrolytic fuel yield of about 67.48% w/w was obtained from converting of 3000 g of plastic waste at pyrolysis time, topt. of 240 minutes and a pyrolysis temperature of 360 °C in a small pilot-scale batch reactor. The characteristic of pyrolytic fuel had an average value of density and viscosity were 771 kg/m3, 1.031 cSt, respectively. The combustion quality as other characteristics of the fuel was obtained as heating value, flash point and auto-ignition point of 37.996 MJ/kg, 48 °C and 240 °C, respectively. The similar functional groups of pyrolytic oil and commercial kerosene fuel were found in Fourier-transform infrared spectroscopy (FTIR) spectrum. This pyrolytic oil provided a higher flame temperature of 1300 °C and a higher thermal efficiency of 33% upon utilized as fuel using a modified pressurized cook stove. These pyrolytic oil’s parameters are close to the standard values of the kerosene fuel.