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The rapid growth of the automotive industry and the resulting accumulation of waste tyres pose significant environmental and public health concerns worldwide. This study explores innovative and sustainable waste tyre management strategies, reviewing conventional methods like landfilling, retreading, and energy recovery, as well as advanced thermo-chemical techniques such as pyrolysis, gasification, and liquefaction. Special emphasis is placed on material recycling pathways, particularly the emerging method of devulcanization, which selectively breaks sulphur bonds in vulcanizec rubber to allow high-quality reuse. The review further evaluates the integration of reclaimed rubber into civil engineering applications and polymer composites, along with recent developments in mechano-chemical, ultrasonic, microwave, and biological devulcanization.
Micro-Brillouin light scattering spectroscopy was applied for the first time, to best of our knowledge, to study the micromechanics of single polyvinylidene fluoride (PVDF) electrospun fibres. Such fibres presenting electroactive properties are developed in view of sensor and energy harvesting applications. Electrospinning is a particularly promising innovative technique allowing the fabrication of nanofibres from a polymeric solution, recognised as a reliable, low-cost, tuneable method to produce fibres in the nanometre to micrometre scale. Depending on the solvent ratio in the electrospinning solution (acetone and dimethylformamide mix), the studied fibres showed a striking difference in the Brillouin spectra and thus elastic properties. These electrospun fibres with different solvents ratio present different surface aspect, and the variation in elastic constant is interpreted in terms of mesoporosity related to solvent evaporation rate. Another very interesting feature is an unexpected elastic anomaly observed in a temperature-dependant study of a single electrospun fibre. Micro-Brillouin spectra show a clear change of slope in the variation of the elastic constant c11 with temperature, similar to what can be observed for a glass transition, at a determined temperature of 31 °C. This temperature does not correspond to the usual glass transition temperature of PVDF, located as described in literature around − 40 °C. This elastic anomaly could be interpreted as a reorientation at the amorphous-crystalline interphase in mechanically oriented materials. A phenomenon of melting of imperfect α crystals happening at lower temperature compared to the main melting temperature of PVDF has also been observed.
The presence of micro-pollutants in aquatic environments poses a significant challenge due to their trace-level concentrations and persistence, which greatly affect public health and ecological safety. Visible-light photocatalysis offers a sustainable solution to this problem. Molybdenum disulfide (MoS2) is gaining interest as an effective photocatalyst due to its tunable band gap and optical properties. Here, we synthesised two MoS2 nanoflowers (NFs) via a simple hydrothermal route at different reaction times: MoS2-1 (shorter reaction time) and MoS2-2 (longer reaction time). XRD, XPS, FE-SEM, and TEM analysis were used to characterize the crystal structure and morphology of the NFs in detail. XRD data confirm the formation of 2H-MoS2, and MoS2-2 shows an increased d-spacing of the characteristic (002) plane and experiences tensile strain, which is supported by the downshift of the binding energy value of the Mo 3d spectra. The FE-SEM and TEM images reveal that a long reaction time yields defective few-layered MoS2 NFs with an average thickness of about 29.64 nm. Additionally, MoS2-2 shows an increased band gap of 1.63 eV compared to MoS2-1, which shows 1.56 eV, further confirming the formation of thin, strained, and few-layered MoS2 NFs at longer reaction times. These synergistic effects: few-layer, strain, and defects, make MoS2-2 an excellent visible-light photocatalyst for degrading methylene blue (MB), tetracycline (TC), and ciprofloxacin (CIP). The increased PL intensity further supports the formation of cracks/defects, which trap excited electrons and reduce the recombination, leaving holes as the major active species for the degradation. The increased carrier density (Nd) of MoS2-2 (3.82 & times; 1016 cm-3) reveals the generation of more charge carriers for photocatalysis. The scavenger studies also confirmed the involvement of holes (h+) and hydroxyl (OH center dot) radicals as the major reactive species, and a possible degradation mechanism was proposed. Density functional theory (DFT) supports these findings, while LC-MS/MS revealed potential intermediates and pathways. This work offers valuable insights for the development of efficient MoS2 nanostructures for environmental remediation.
Water splitting technology enables the generation of green hydrogen, simultaneously offering a route for sustainable brine electrolysis to produce sodium hypochlorite (NaOCl). Herein, we report a multifunctional Ag/Co3O4/MXene nanocomposite catalyst active for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) while also facilitating NaOCl production from brine water oxidation. XRD results showed that Ag incorporation reduced the crystallite size of Co3O4, and FTIR analysis confirmed the improved hydrophilicity of the Ag/Co3O4 catalyst resulting from MXene integration. Strong interfacial interactions between MXene and Ag/Co3O4 were established by XPS, leading to oxygen-mediated interfacial bonding and associated charge redistribution, thereby enhancing the catalytic behavior. Electrochemical evaluation demonstrated bifunctional performance, with OER and HER activities comparable to those of RuO2 and Pt/C benchmark catalysts, respectively. Additionally, the catalyst remained stable during extended OER (25 h) and HER (20 h) testing as well as overall water splitting for 30 h at 100 mA cm-2. Importantly, the catalyst achieved the highest reported value of electrochemically synthesized NaOCl yield, 12 g L-1, under optimized conditions, including current density, temperature, electrolysis time, and NaCl concentration (40 mA cm-2, 20 degrees C, 3-21 h, and 40 g L-1, respectively). These results highlight Ag/Co3O4/MXene as a versatile electrocatalyst for sustainable energy conversion and chemical production.
Cellulose was extracted from cactus (Opuntia ficus-indica) cladodes using an ultrasound-assisted technique with water or 80
