Study on the structure-activity mechanism of slurry prepared by co-blending corn stalk biochar and coal

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In this study, corn straw was used as the raw material and subjected to low-temperature pyrolysis in a tubular furnace within the range of 400–500 °C to investigate the effects of pyrolysis temperature on the physicochemical properties of biochar and the migration behavior of alkali metal potassium (K). Elemental analysis, FT-IR, SEM and BET techniques were employed to examine the effects of temperature on the properties of biochar. The results showed that with increasing pyrolysis temperature, the fixed carbon content increased, while the volatile matter and oxygen-containing functional groups decreased. The pore structure gradually developed, with the specific surface area and pore volume reaching their maximum values at 475 °C. The total K content decreased with increasing temperature, and its occurrence transformed from water-soluble to organic-bound and residue-bound forms. When the biochar was blended with coal to prepare biochar-coal-water slurry, it was found that within 400–475 °C, potassium ions reacted with carboxyl groups to form potassium carboxylates, reducing hydrophilic groups and enhancing particle hydrophobicity, consequently, the fluidity of the multicomponent slurry is improved and its viscosity is reduced. At 500 °C, mineral deposition led to pore blockage and increased its viscosity. Furthermore, surface modification of biochar particles with kerosene significantly improved the performance of the multicomponent slurry, increasing the maximum slurry concentration by about 2.6%. The study elucidates the structure-activity mechanisms governing the performance of co-slurrying corn-stalk pyrolysis char with coal, providing a theoretical basis for the efficient utilization of biochar in coal-water slurry systems and broader energy applications. Download: Download high-res image (89KB) Download: Download full-size image

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