An alkaline form of ‘dry water’—a ‘dry base’—is prepared by the high-speed mixing of aqueous solutions of metal carbonates or organic amines with hydrophobic silica nanoparticles.
In this paper, the applicability of mechanical tests for biomass pellet characterisation was investigated. Pellet durability, quasi-static (low strain rate), and dynamic (high strain rate) mechanical tests were applied to mixed wood, eucalyptus, sunflower, miscanthus, and steam exploded and microwaved pellets, and compared to their Hardgrove Grindability Index (HGI), and milling energies for knife and ring-roller mills. The dynamic mechanical response of biomass pellets was obtained using a novel application of the Split Hopkinson pressure bar. Similar mechanical properties were obtained for all pellets, apart from steam-exploded pellets, which were significantly higher. The quasi-static rigidity (Young’s modulus) was highest in the axial orientation and lowest in flexure. The dynamic mechanical strength and rigidity were highest in the diametral orientation. Pellet strength was found to be greater at high strain rates. The diametral Young’s Modulus was virtually identical at low and high strain rates for eucalyptus, mixed wood, sunflower, and microwave pellets, while the axial Young’s Modulus was lower at high strain rates. Correlations were derived between the milling energy in knife and ring roller mills for pellet durability, and quasi-static and dynamic pellet strength. Pellet durability and diametral quasi-static strain was correlated with HGI. In summary, pellet durability and mechanical tests at low and high strain rates can provide an indication of how a pellet will break down in a mill.
Olive pomace is a widely available agro-industrial waste residue in Europe that has the potential to contribute towards a circular, low carbon bio-economy. This study demonstrated, for the first time, the ability to successfully pyrolyse olive pomace with microwaves for the production of bio-char and bio-oil. It was found that the energy requirement needed to pyrolyse up to 80 % of the olive pomace was as low as 3.6 kJ/g and bio-oil yields up to 30 % were produced. Microwave power did not influence the overall yields or the chemical composition of the obtained bio-oils, but did alter the textural properties of the generated bio-chars and their ability to remove methylene blue dye. Optimum processing conditions were found to be within the 3.6 kJ/g energy requirement with a microwave power of 200 W and processing time of 180 sec. These conditions produced a bio-oil fraction containing mainly acetic acid (71.9 %) and a bio-char with a surface area of 392.3 m 2 /g, micropore volume of 0.15 cm 3 /g and a methylene blue removal efficiency of 40 qMB mg/g. The results acquired from this study reveal the superiority of microwave heating in a pyrolysis system and highlight a novel and prospective route for added value recovery from natural waste resources like olive pomace.
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