Synthesis of Sulfur@g-C3N4 and CuS@g-C3N4 Catalysts for Hydrogen Production from Sodium Borohydride

In this work, the S@g-C₃N₄ and CuS@g-C₃N₄ catalysts were prepared via the polycondensation process. The structural properties of these samples were completed on XRD, FTIR and ESEM techniques. The XRD pattern of S@g-C₃N₄ presents a sharp peak at 27.2° and a weak peak at 13.01° and the reflections of CuS belong to the hexagonal phase. The interplanar distance decreased from 0.328 to 0.319 nm that facilitate charge carrier separation and promoting H₂ generation. FTIR data revealed the structural change according to absorption bands of g-C₃N₄. ESEM images of S@g-C₃N₄ exhibited the described layered sheet structure for g-C₃N₄ materials and CuS@g-C₃N₄ demonstrated that the sheet materials were fragmented throughout the growth process. The data of BET revealed a higher surface area (55 m²/g) for the CuS-g-C₃N₄ nanosheet. The UV-vis absorption spectrum of S@g-C₃N₄ showed a strong peak at 322 nm, which weakened after the growth of CuS at g-C₃N₄. The PL emission data showed a peak at 441 nm, which correlated with electron-hole pair recombination. The data of hydrogen evolution showed improved performance for the CuS@g-C₃N₄ catalyst (5227 mL/g·min). Moreover, the activation energy was determined for S@g-C₃N₄ and CuS@g-C₃N₄, which showed a lowering from 47.33 ± 0.02 to 41.15 ± 0.02 KJ/mol.

Biocrude oil production via hydrothermal liquefaction of food waste in a simplified high-throughput reactor

In this study, the hydrothermal liquefaction of food waste was investigated for generating bio-oils or biocrudes using a simplified high-throughput reactor. Different operating conditions were parametrically tested for obtaining maximum yield of biocrudes at temperatures from 280 to 340 °C and sample-to-water mixture ratios from 1:3 to 1:7, with 30 min residence time. The biocrude yields were found to increase significantly with increasing temperature and mixture ratio. A maximum biocrude yield of approximately 40% w/w dry basis (from a total liquid product yield of over 56% w/w) and energy recovery of over 70% were obtained at 340 °C and a mixture ratio of 1:7. High heating values of the resulting biocrude and solid residue were remarkably better than those of the raw material. Fatty acids, amides, N-containing compounds, and cyclic ketones were identified to be the main components of the biocrudes using advanced GCxGC/TOF-MS.