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Cigarette butts (CBs) are emerging polluting toxic plastic and microplastic elements that present a major challenge to environmental issues and recycling technologies. This is due to their complex composition consisting of cellulose acetate, cigarette paper, tar particles, tobacco, and heavy metals, thus, making it difficult to mechanically recycle, landfill, or incinerate them. In order to maximize their economic performance, this research aims to convert CBs into valuable volatile and chemical products using thermochemical treatment. Pyrolysis experiments were performed on each CB component separately (paper, filter, and tobacco) and their mixture (MIX) to determine the most complex part in the reaction and their effect on the synthesized pyrolysis vapour (PV) products. The experiments were carried out using thermogravimetric analyser (TGA) at heating rates 5, 10, 15, 20, 25, and 30 °C/min. The PVs generated from each batch under the specified heating conditions were analysed using Fourier transform infrared spectroscopy (TG/FTIR) and gas chromatography–mass spectrometry (GC/MS). Meanwhile, the complexity of reaction of CB components was investigated using three isoconversional model-free methods (Friedman, KAS, and FWO) and two nonlinear isoconversional models (Vyazovkin and Cai). The FTIR results showed that the PV products were rich in aromatic hydrocarbons (paper), carbonyl C = O (filter), CO2 (tobacco), and CO2 and carbonyl C = O (MIX). Whereas, phenol (paper; 42%), acetic acid (filter; 94%), pyridine (tobacco; 45%), and acetic acid (MIX: 74%) were the major GC/MS compounds at lower heating rates, and phenol (paper; 50%), acetic acid (filter; 93%), pyridine (tobacco; 39%), and several compounds in MIX sample (propanal, acetic acid, propanone, limonene, and pyridine) were manifested at higher heating rates. Finally, the kinetic results showed that tobacco represents the most complex part in decomposition of CBs (348 kJ/mol) compared to paper (238 kJ/mol) and filter (269 kJ/mol). Meanwhile, mixing all these components together reduced the complexity up to 184 kJ/mol (MIX), which contributed to decrease in energy consumption during the treatment at industrial scale. [ABSTRACT FROM AUTHOR]

This study investigated biomass (wood pellets) gasification to syngas using direct current (DC) thermal arc plasma at atmospheric pressure. Water vapor was used as a main gasifying agent and a plasma-forming gas. The biomass gasification system was quantified in terms of the producer gas composition, the tar content, the H2/CO ratio, the carbon conversion efficiency, the energy conversion efficiency and the specific energy requirements. It was found that the gasification performance efficiency was highest at the water vapor-to-biomass ratio of 0.97. The producer gas was mostly composed of H2 (43.86 vol.%) and CO (30.93 vol.%), giving the H2/CO ratio of 1.42 and the LHV of 10.23 MJ/Nm3. However, high content of tars of 13.81 g/Nm3 was obtained in the syngas. The yield of H2 and CO was 48.31% and 58.13%, respectively, with the highest producer gas yield of 2.42 Nm3/kg biomass. The carbon conversion efficiency and the energy conversion efficiency were 100% and 48.83%, respectively, and the production of 1 kg of syngas required 1.78 kWh of electric energy input. Finally, the obtained results were compared with different plasma methods, including plasma-assisted application coupled with conventional gasification. [ABSTRACT FROM AUTHOR]

The recovery of short fibre and epoxy resin from glass fibre-reinforced epoxy resin composites (GFRP) poses a major challenge to the waste recycling sector. These challenges grow when GFRP is mixed with other additives such as carbon nanotubes (CNTs), graphene (GA), and carbon black particles (CB). However, the complexity in terms of activation energy (Ea) can be decreased through involvement of ZSM-5 zeolite catalyst in the pyrolysis process to convert resin component into chemical and energy products. Within this context, this research aims to study the catalytic pyrolysis of GFRP mixed with three fillers with different structures and dimensions (nanofillers "CNTs, GA" and micro-filler "CB") over zeolite catalyst, where these fillers can be used alongside zeolite particles as hybrid catalysts during the thermal conversion process. The GFRP mixed with different filler panels were prepared in the laboratory using a vacuum-assisted resin transfer method, then they were ground to fine particles and mixed with 200 mass% of ZSM-5 catalyst to prepare them for thermochemical experiments using thermogravimetry (TGA) at 5–30 °C min−1. The effect of various hybrids on the formulated pyrolysis vapours was studied using TG-FTIR and GC–Ms measurements. The kinetic Ea of each batch was studied using three linear isoconversional methods and two nonlinear isoconversional methods to investigate their effect on the decomposition mechanism. Besides, their thermochemical decomposition curves (TGA-DTG) were numerically simulated using DAEM and IPR models. The FTIR and GC analyses revealed that the hybrid catalyst had enhanced formation of aliphatic compounds and phenol compound in case of nanofillers up to 54% (CNTs) and 57% (GA), hence improving them by 17 and 54%, respectively. Meanwhile, the kinetic analysis showed that hybrid catalysts can contribute to a significant reduction in Ea up to 158 kJ mol−1 (CNTs), 127 kJ mol−1 (GA), and 124 kJ mol−1 (CB), which means that the decomposition of GFRP, becomes easier and requires less energy. Also, the simulated and experimental results showed big consistency in terms of smaller reaction complexity and higher generation of volatile compounds with increasing heating rates and addition of hybrid catalysts. [ABSTRACT FROM AUTHOR]

Environmental contamination at shooting ranges is a widely known ecological problem. The aim of the study was to evaluate the extent of contamination and the ecotoxicity of a shooting range soil assessing the physiological and biochemical effects on earthworm Eisenia fetida (Savigny). Adult E. fetida were exposed to the soils collected from different distances of the shooting range for 28 days. High concentrations of Pb (53023 mg kg−1), increased concentrations of Ni (12 mg kg−1) and Sb (600 mg kg−1), significantly higher soil organic matter content (7.2%) and density (6.14 g cm−3) were determined in the backstop berm soil. Significant weight loss (44.4%) of the adult earthworms after 28 days of exposure occurred in the most contaminated shooting range soil and significantly higher concentrations of Pb (3101 mg kg−1), Cu (51 mg kg−1), Ni (2 mg kg−1), and Sb (20 mg kg−1) were determined in the tissues of worms, and no juveniles found there. Juveniles exposed to the less contaminated soil of the shooting range (A, B and C) accumulated significant concentrations of Pb, Cu, Fe, Mn, and Zn. The antioxidant enzymatic activity (glutathione-s-transferase (GST)) decreased, and lipid peroxidation increased as indicated by an increase in malondialdehyde (MDA) level in earthworms exposed to the contaminated soil. A compensatory mechanism between the activities of glutathione reductase (GR) and GST in earthworms exposed to these soils was confirmed. [ABSTRACT FROM AUTHOR]

The levels of heavy metals that accumulated in stemwood of mature trees grown for 20 years in a plantation in an abandoned peat quarry in areas that were fertilized with different amounts of domestic sewage sludge (180, 360, and 720 Mg ha−1 on a dry basis) were compared with trees grown in a reference nonfertilized area. Included in the study was a hybrid poplar (Populus tremula × Populus tremuloides) developed for use as an energy crop, three local tree species and one introduced tree species. The concentrations of Cd, Cr, Cu, Ni, Pb and Zn in the stemwood of the trees grown in the fertilized and nonfertilized fields were determined, and found to be significantly lower than their respective concentrations in the soil. Cd and Cr were found only in several wood samples at concentrations close to the limits of detection or qualification; therefore, they were not analyzed further. A correlation analysis suggested that 75% of the correlations between the concentrations of heavy metals in the stemwood and the concentrations in the soil were negative. The ability of trees to accumulate the metals from soil in most cases decreased for Cu and Ni; however, the correlations were not as clear for Pb and Zn. The following sequence for the levels of heavy metals found in the stemwood of the analysed trees was Zn > Pb > Ni > Cu > (Cr, Cd). The results of this study showed that the levels of heavy metals in the studied wood would not exceed the permitted limits of heavy metal pollution in the air and ash when used for energy production. [ABSTRACT FROM AUTHOR]