• Energy Research

The COVID-19 pandemic has caused a heavy expansion of plastic pollution due to the extensive use of personal protective equipment (PPE) worldwide. To avoid problems related to the entrance of these wastes into the environment, proper management of the disposal is required. Here, the steam gasification/pyrolysis technique offers a reliable solution for the utilization of such wastes via chemical recycling into value-added products. The aim was to estimate the effect of thermo-chemical conversion temperature and steam-to-carbon ratio on the distribution of gaseous products obtained during non-catalytic steam gasification of 3-ply face masks and KN95 respirators in a fluidized bed reactor. Experimental results have revealed that the process temperature has a major influence on the composition of gases evolved. The production of syngas was significantly induced by temperature elevation from 700 °C to 800 °C. The highest molar concentration of H2 gases synthesized from both types of face masks was estimated at 800 °C with the steam-to-carbon ratio varying from 0 to 2. A similar trend of production was also determined for CO gases. Therefore, investigated thermochemical conversion process is a feasible route for the conversion of used face masks to valuable a product such as syngas.

Abstract Metallised food packaging plastics waste (MFPW) is the most complex part of plastic waste ever with poor recyclability. In order to close the circle loop of MFPWs and to increase their economic and environmental benefits according to the zero waste principle, this research aims to convert MFPWs into energy products (Microcrystalline paraffin wax and biogas) and raw materials (carbon particles and aluminum) using three combined approaches: pyrolysis, mechanical and chemical treatments. The thermal treatment using mini-pyrolysis plant (capacity of 250 g) was applied as the main treatment to convert MFPWs into three main energy products: biooil, biogas, and char mixed with aluminum flakes (Al/char) at 25 °C/min up to 500, 600, and 700 °C, while the mechanical treatment using milling process was used to break the bonds between char and Al flakes, thus liberating Al flakes after sieving process. Finally, the leaching process using hydrochloric acid was employed to extract the remaining Al particles from the milled Al/char and to recover the carbon particles simultaneously, using a density separation method. The experiments were performed on a mixture of five types of equal shares of packages (potato chips, chocolate, bakery, coffee, and biscuits). The obtained energy products and recovered materials were analyzed by GC, FTIR, ICP, and SEM-EDS. The results showed that MFPWs can be decomposed thermally into Al/char (99.4%) only up to 500 °C, while in case of 600 and 700 °C, they can be converted into microcrystalline paraffin wax (19.5%), biogas (63%), and Al/char (17.8%). Also, the mechanical and chemical treatments were succeeded by leaching >90 wt% of Al and extraction of carbon particles on a micro-scale (10–50 μm). Finally, the assessment of economic performance and greenhouse gases showed that application of the developed approach on an industrial scale can provide an economic return up to 610 $/ton of MFPWs and decrease carbon footprint by −984 kg CO2-eq/t of MFPWs.

The remarkable properties of polysulfone (PSF) membranes have contributed to their use in many ultrafiltration applications. Meanwhile, this huge usage of PSF films and its short service life have generated a huge amount of waste PSF films that need to be managed carefully. Within this framework, this is the first research specifically developed to valorize the end-of-life of PSF membranes and convert them into high-value chemical and energy products using pyrolysis treatment. The treatment was performed using a thermogravimetric analyzer (TGA), while the structure and abundance of the phenol and benzoic acid compounds in the generated vapor were determined using Fourier-transform infrared (FTIR) spectroscopy and Gas chromatography-mass spectrometry (GC-MS). Thermogravimetric recorded data at different conditions (5–30°C/min) was subjected to linear and nonlinear models including KAS, FWO, Friedman, Vyazovkin, and Cai to assess the pyrolytic kinetic behavior of PSF films. The films showed higher content of volatile matter (57%), lower NOx emissions (0.321%), and a little bit more SOX emission (6.909%). The GC-MS showed that the pyrolytic gaseous products are rich in phenol (24.3%) and benzoic acid (52.4%) compounds and the highest abundance was achieved at 30°C/min. Whereas activation energies were estimated in the range of 193–240 kJ/mol based on linear kinetic criteria versus 161–163 kJ/mol in the case of nonlinear models, where R2 values (>0.91) indicated perfection. Also, distributed activation energy and independent parallel reaction kinetic models showed a good fit with the TGA-DTG experimental data with the minimum deviation. The study confirmed the potential of pyrolysis treatment in converting wasted PSF films into a new source for the recovery of phenolic and benzoic acid.

Lint-microfibers (LMs) generated during clothes drying are classified as primary microplastics and consist mainly of cotton, polyester and lignin. This research aims to convert LMFs into energy products using a pyrolysis treatment. The pyrolysis experiments were performed using a pilot pyrolysis plant. SEM-EDS was used to observe the morphology and elemental composition of the feedstock and the obtained biochar, while a digital unit of Instantaneous Gas analyzer and Gas chromatography (GC) were used to observe the concentration of O2, N2, CO2, CO, H2, CH4 gases during the whole conversion process. Finally, a simple mathematical model was developed to evaluate the economic and environmental performance of the suggested strategy based on the LMFs generated by one million persons. Based on the results of the developed model and yield of pyrolysis process, around 45 tons of LMFs are generated by one million persons annually and this amount is enough to produce 13.8 tons of oil (~31%), 21.5 tons of gas (47.7%), and 9.7 ton of char (21.6%) with estimated profitability of 120,400$ and reduction in carbon footprint estimated at -42,039,000kg CO2-eq/t of LMFs.

Abstract Mango waste is one of the most promising sources of renewable energy, especially as this waste represents 40% of the weight of mango fruit and contains a large amount of fat and cellulose that can contribute to converting it into energy products using pyrolysis and gasification process. Within this context, this research aims to investigate pyrolysis and gasification kinetic behavior of mango seed shells (MSS) using TG-FTIR-GC–MS system. The experiments were started by analyzing the composition of different types of Egyptian MSS, then their pyrolysis characteristics and chemical decomposition in N2 and CO2 atmospheres using TG-FTIR system upto 900 °C at heating rates in the range 5–30 °C/min were studied. The GC/MS system was employed to determine the formulated volatile products at the maximum decomposition temperatures (343–346 °C for N2 and 334–340 °C for CO2). Afterwards, the model-free/model-fitting methods, including Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa, and Friedman, and Distributed Activation Energy Model (DAEM) were used to estimate the kinetic parameters of pyrolysis of MSS in both atmospheres. Finally, chars derived from pyrolysis were exposed to CO2 gasification process, followed by studying of their kinetic behavior in the modified random pore model (MRPM). The results showed that the decomposed MSS were saturated with a huge amount of volatile products, particularly Carbon dioxide and Ethylene oxide (99.27% in CO2 and 20.77% in N2), while Acetic acid, Propanone, Hexasiloxane, Glycidol, Ethanedial, Ethylene oxide, Formic acid, etc. were the main compounds in case of N2. Meanwhile, the studies of kinetics of pyrolysis showed that the average activation energies were estimated in the range of 231–262 kJ/mol (N2) and 259–333 kJ/mol (CO2). Based on that, pyrolysis and gasification can be adapted as promising technologies to valorize MSS and utilize them as a new sustainable source for renewable energy.

For the future energy markets, where the role of fossil fuels will be minimized and district heating systems will become more efficient through the use of waste streams, a new concept is proposed based on tri-generation of Fischer–Tropsch (FT) products, heat, and power. The challenge of combining the transport sector with a District Heating (DH) network and power grid is presented in this article by discussing the operating modes of the gasifier, FT product output (as a raw material for refinery) and waste stream generated after the synthesis reactor, preliminary process management schemes, market factors, and economic attractiveness. The feasibility of the concept was examined for an existing combined heat and power plant in Lithuania, which could become a potential demo plant. To demonstrate the feasibility of this concept, which may help create independence from fossil fuels through the use of syngas (for a sudden increase in heat demand), a techno-economic assessment was performed. The analysis of various scenarios showed that the cost of the FT product may be between 0.67 and 1.47 €/kg for gasifier capacities ranging from 10 to 40 MW. However, the economic attractiveness assessment revealed that the concept is profitable at a liquid biofuel (FT product) prime cost below 1.07 €/kg (without electrolysis capability).

Abstract Char derived from pyrolysis of plastic wastes represents about 20 wt.% of the released pyrolysis products. In order to maximize the economic benefits and applications of this fraction, this research aims to refine and reprocess char derived from plastic waste into carbon particles, then using it as a micro-filler material for light material applications. The experiments were performed on char derived from pyrolysis of metallised food packaging plastics wastes (MFPWs) that represent the most complicated part in plastic waste, and their char is usually loaded with aluminium elements. The experiments started with treating MFPWs in pyrolysis plant with a capacity of 250 g, followed by separation of char from other pyrolysis products. The derived char was exposed to a milling process followed by a leaching process to separate Al fraction and other heavy metals. The liberated carbon particles were exposed to functionalization process to remove any contamination and amorphous impurities. The functionalized carbon black particles in the form of spherical microparticles (FBC: 0.25, 0.5, 0.75, and 1 wt.%) were used to enhance the mechanical impact, and thermal behaviour of fiberglass/epoxy composite laminates. The composite panels were prepared using vacuum-assisted resin transfer and curing processes. The morphology and the composition of FBC were examined using SEM-EDS and FTIR. Also, SEM and Optical Microscope were used to observe dispersion of FBC, microstructure, impact mechanism, and surface morphology of the fabricated matrix. The mechanical and impact properties of the panels were tested according to ASTM-D7025 and ISO 6603-2 standards, respectively. Finally, thermal behaviour of the panels was studied using a thermogravimetric analysis. The results showed that 0.75 wt.% of FBC were enough to improve the modulus of elasticity of panels by ∼22 %, compared to a pure sample. In addition, thermal stability and energy impact absorption at the same concentration of FBCs were improved by 21 % (in the main decomposition zone) and 38 %, respectively.

Recovery of carbon fibres and resin from wind turbine blade waste (WTB) composed of carbon fibres (CF)-reinforced unsaturated polyester resin (UPR) has been environmentally challenging due to its complex structure that is not biodegradable and that is rich in highly toxic styrene (main component of UPR). Within this framework, this paper aims to liberate CF and UPR from WTB using a pyrolysis process. The treatment was performed on commercial WTB (CF/UPR) up to 600 °C using a 250 g reactor. The UPR fraction was decomposed into liquid and gaseous phases, while CF remained as a residue. The composition of gaseous phase was monitored during the entire treatment using a digital gas analyser, while gas chromatography-mass spectrometry (GC-MS) was used to characterize the collected liquid phase. CF fraction was collected and exposed to additional oxidation process after treatment at 450 °C for purification propose, then it was analysed using FTIR and SEM-EDX. Finally, the life cycle assessment (LCA) of the CF/UPR pyrolysis was studied using SimaPro software and the results were compared with landfill disposal practices. The pyrolysis results manifested that 500 °C was sufficient for UPR decomposition into styrene-rich oil and gaseous products with yields of 15.23 wt% and 6.83 wt%, respectively, accompanied by 77.93 wt% solid residue including CF. The LCA results showed that pyrolysis with oxidation process has high environmental potential in WTB recycling with significant reduction in several impact categories compared to landfill. However, the pyrolysis scenario revealed several additional environmental burdens related to ecosystems, acidification, Ozone formation, and fine particulate matter formation that must be overcome before upscaling.