The growing population and economic expansion have led to increased energy demand while presenting complex waste generation and management challenges, particularly in light of climate change. Green hydrogen, which is considered a major clean energy carrier, can also be generated from food waste through a process known as dark fermentation. The production of dark fermentative hydrogen from food waste and biomass residues, in general, is influenced by the type of feedstock, source of inoculum, and their pretreatment and handling strategies. Food waste is a suitable substrate for dark fermentation and has a variable and complex composition, which is a major factor limiting the hydrogen yield. This review critically assesses food waste sources, focusing on their physical and chemical composition, pretreatment methods, and strategies for optimizing dark fermentative hydrogen production. This paper also highlights and critically discusses various inoculum sources and innovations regarding the pretreatment and enrichment applications of inocula for dark fermentative hydrogen production. Based on the literature analysis, advanced research is required to develop more sustainable and specific pretreatment strategies that consider the properties of food waste and the source of the inoculum. This approach will aid in preventing inhibition and inefficiency during the dark fermentation process.

This work was focused on carbonizing four tropical fruits shells wastes such as: coconut shells (CS), palmyra shells (PS), doum palm shells (DPS), whole fruit of doum palm (WFDP) and teak wood (TW) used as control. The aim was to investigate the potential of those biochar to be used as an alternative energy source in replacement ofcharcoal. The raw biomasses samples were carbonized under the same conditions and some combustion characteristics of the obtained biochar such as lower calorific value, energy per unit volume associated to bulk density, ash content, moisture content and ash mineral content were investigated. The temperature in the furnace was estimated during carbonization process using a K-type thermocouple. The thermal profile of the studied raw biomasses reveals three phases of carbonization. The biochar yield drops significantly for all biomasses as the final maximum temperature increases. The average yields obtained ranged from 37.81 % for palmyra shells to 27.57 % for the doum palm shells. The highest yield achieved was 42.32 % obtained at 280 °C for palmyra shells, the lowest yield (24.42 %) was recorded at the highest maximum temperature of 590 ° C for doum palm shells. The results of energy parameters of the studied biochar showed that coconut shells charcoal presented the highest lower calorific value (28.059 MJ.kg-1), followed by doum palm shells (26.929 MJ.kg-1) when, with 25.864 MJ.kg-1, whole fruit of doum palm charcoal showed the lowest lower calorific value. Similarly, with the highest bulk density of 0.625 g/cm3 coconut shells charcoal presented the highest energy per unit volume (17536.88 J/cm3), whereas with the lowest bulk density of 0.415 g/cm3, whole fruit of doum palm charcoal presented the lowest energy per unit volume. The ash content analysis showed that whole fruit of doum palm had the highest ash content (18.75 %) and palmyra nut shells charcoal (8.42 %).Teak wood charcoal, took as control, has the highest lower calorific value (32.163 MJ.kg-1), less dense as coconut shell (0.43 g/cm3), his energy per unit of volume is 13830.09 j/cm3 but the lowest value of as content (2.90 %). Among these biomasses charcoals, only whole fruit of doum palm charcoal ash showed a high chloride and sulfide content respectively 9.73 % and 1.75 % in weight. From these results, the produced charcoals could be used as alternative fuels except for whole fruits of doum palm charcoal which chloride and sulfide content were found high. ©2020. CBIORE-IJRED. All rights reserved

Graphene-based photodetection (PD) devices have been broadly studied for their broadband absorption, high carrier mobility, and mechanical flexibility. Owing to graphene’s low optical absorption, the research on graphene-based PD devices so far has relied on hybrid heterostructure devices to enhance photo-absorption. Designing a new generation of PD devices supported by silicon (Si) film is considered as an innovative technique for PD devices; Si film-based devices are typically utilized in optical communication and image sensing owing to the remarkable features of Si, e.g., high absorption, high carrier mobility, outstanding CMOS integration. Here, we integrate (i) Si film via a splitting/printing transfer with (ii) graphite film grown by a pyrolysis method. Consequently, p-type Si film/graphite film/n-type Si-stacked PD devices exhibited a broadband detection of 0.4–4 μm (in computation) and obtained good experimental results such as the responsivity of 100 mA/W, specific detectivity of 3.44 × 10⁶ Jones, noise-equivalent power of 14.53 × 10⁻¹⁰ W/(Hz)^1/2, external quantum efficiency of 0.2, and rise/fall time of 38 μs/1 μs under 532 nm laser illumination. Additionally, our computational results also confirmed an enhanced light absorption of the above stacked 2D heterostructure film-based PD device compatible with the experimental results.

Climate change and the growing demand for energy have prompted research on alternative eco-friendly energy sources. This study focused on the potential for biogas production from water hyacinth and banana peel waste through physicochemical characterization and batch anaerobic digestion tests. The water hyacinth and banana peel samples were dried, ground, and subjected to elemental, proximate, and fiber content analyses. Subsequently, banana peel waste, water hyacinth stems, and leaves were used for batch anaerobic digestion tests in 500 mL glass flask bottles for 21 days under mesophilic conditions in n = 3 trials. Kruskal–Wallis and Dunnett’s tests were performed to identify the significance of the differences in biogas yield among the samples. The analyses of the elemental, proximate, and fiber contents of water hyacinth and banana peels revealed that they possess a suitable chemical composition and essential nutrients for the production of high-yield biogas. The biogas yields from water hyacinth leaves, stems, and banana peels were 280.15, 324.79, and 334.82 mL/g VS, respectively. These findings indicate that water hyacinth and banana peel waste have significant potential for biogas production.

In a plant microbial fuel cell (P-MFC), the plant provides the fuel in the form of exudates secreted by the roots, which are oxidised by electroactive bacteria. The immature plant is hampered by low energy yields. Several factors may explain this situation, including the low open-circuit voltage of the plant cell. This is a function of the development of the biofilm formed by the electroactive bacteria on the surface of the anode, in relation to the availability of the exudates produced by the roots. In order to exploit the fertilising role of biochars, a plant cell was developed from C. citratus and grown in a medium to which 5% by mass of coconut shell biochar had been added. Its effect was studied as well as the distance between the electrodes. The potential of Cymbopogon citratus was also evaluated. Three samples without biochar, with inter-electrode distances of 2, 5 and 7 cm, respectively, identified as SCS2, SCS5 and SCS7, and three with the addition of 5 % biochar, with the same inter-electrode distance values, identified as S2, S5 and S7, were prepared. Open-circuit voltage (OCV) measurements were taken at 6 a.m., 1 p.m. and 8 p.m. The results showed that all the samples had high open-circuit voltage values at 1 p.m. Samples containing 5% biochar had open-circuit voltages increased by 16 %, 8.94% and 5.78%, respectively, for inter-electrode distances of 2, 5 and 7 cm compared with those containing no biochar. Furthermore, the highest open-circuit voltage values were obtained for all samples with C. citratus at an inter-electrode distance of 5 cm. The maximum power output of the PMFC with C. citratus in this study was 75.8 mW/m², which is much higher than the power output of PMFCs in recent studies.

Carbon-based electrodes have recently been most widely used in P-MFC due to their desirable properties such as biocompatibility, chemical stability, affordable price, corrosion resistance, and ease of regeneration. In general, carbon-based electrodes, particularly graphite, are produced using a complex process based on petroleum derivatives at very high temperatures. This study aims to produce electrodes from bio-pitch and charcoal powder as an alternative to graphite electrodes. The carbons used to manufacture the electrodes were obtained by the carbonisation of Robinia pseudoacacia and Azadirachta indica wood. These carbons were pulverised, sieved to 50 µm, and used as the raw materials for electrode manufacturing. The binder used was bio-pitch derived from coconut shells as the raw materials. The density and coking value of the bio-pitch revealed its potential as a good alternative to coal-tar pitch for electrode manufacturing. The electrodes were made by mixing 66.50% of each carbon powder and 33.50% of bio-pitch. The resulting mixture was moulded into a cylindrical tube 8 mm in diameter and 80 mm in length. The raw electrodes obtained were subjected to heat treatment at 800 °C or 1000 °C in an inert medium. The electrical resistivity obtained by the four-point method showed that N1000 has an electrical resistivity at least five times lower than all the electrodes developed and two times higher than that of G. Fourier-transform infrared spectroscopy (FTIR) was used to determine the compositional features of the samples and their surface roughness was characterised by atomic force microscopy (AFM). Charge transfer was determined by electrical impedance spectroscopy (EIS). The FTIR of the electrodes showed that N1000 has a spectrum that is more similar to that of G compared to the others. The EIS showed the high ionic mobility of the ions and therefore that N1000 has a higher charge transfer compared to G and the others. AFM analysis revealed that N1000 had the highest surface roughness in this study.