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This work presents a comparative study of the physicochemical properties of chars derived by three thermochemical pathways, namely: hydrothermal carbonization, HTC (at 180, 200 and 220 °C), pyrolysis, PY, (at 500, 600 and 700 °C) and microwave assisted pyrolysis, MW (at 300, 450 and 600 W). The mass yield of HTC samples showed a decrease (78.7 to 26.7%) as the HTC temperature increased from 180 to 220 °C. A similar decreasing trend in the mass yield was also observed after PY (28.45 to 26.67%) and MW (56.45 to 22.44%) of the food waste mixture from 500 to 700 °C and 300 to 600 W, respectively. The calorific value analysis shows that the best among the chars prepared by three different heating methods may be ranked according to the decreasing value of the heating value as: PY500, MW300, and HTC180. Similarly, a decreasing trend in H/C values was observed as: PY500 (0.887), MW300 (0.306), and HTC180 (0.013). The scanning electron microscope (SEM) analyses revealed that the structure of the three chars was distinct due to the different temperature gradients provided by the thermochemical processes. The results clearly show that the suitable temperature for the HTC and PY of food waste was 180 °C and 500 °C, respectively, while the suitable power for the MW of food waste was 300 W. [ABSTRACT FROM AUTHOR]

In this work, Pd nanoparticles immobilized Cu 2 O@CuO heterojunction catalysts were synthesized through a facile one-pot green solution combustion technicality using the pomegranate seed extract as reducing mediator/capping fuel during the combustion process. The findings showed that pomegranate seeds extract within a feasible content of biogenic capping components demonstrate a microspheres Pd/Cu 2 O@CuO with Hydrangea flower-like fibrous structure, higher porosity, the adaptable ratio of Cu+/Cu2+, and Pd°/Pd2+. Even further, the bio-inspired Pd/Cu 2 O@CuO heterojunction catalysts were exploited in CO oxidation and olefins epoxidation. The bio-inspired 0.5 wt% Pd/Cu 2 O@CuO provides 100 % conversion of CO at 99 °C and 99 % for cyclohexene epoxidation compared to 220 °C and 81 % for Cu 2 O@CuO. CuO and Cu 2 O NPs offer distinctive active centers for respectively, the dissociation of oxygen and CO oxidation. The nanoscale spacing between CuO and Cu 2 O zone and Pd NPs dispersion are beneficial to the quick movement of the adatom oxygen over Cu 2 O to cover the vacancies of oxygen on CuO and thereby enhance the catalytic activity for low-temperature CO oxidation and epoxidation processes through a synergetic mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]