The combination of hydrothermal humification and biological fermentation converts straw lignocellulose into...

In order to solve the problem of difficult efficient utilization and production of lignocellulosic macromolecules in crop straw, as well as the high pollution production of fulvic acid (FA). We developed an efficient biomass conversion technology that combines hydrothermal humification and biological fermentation in a low alkaline environment. Discussed material conversion and FA structural composition. FA was produced through five steps, namely, enzymatic hydrolysis, hydrothermal treatment, concentration, fermentation and spraying, with a maximum yield of 39 %. The optimal enzymatic hydrolysis conditions were 0.2 % hemicellulase, 50 °C and 6 h. The optimal hydrothermal conditions were 5 % KOH, 160 °C and 2 h. The optimal distillation conditions were 50 °C for 25 min. The optimal conditions for microbial fermentation were 0.02 % Bacillus subtilis/Bacillus licheniformis, 35 °C and of 48 h. Finally, high-temperature spraying was performed at 240 °C. Under these conditions, benzofuran, 2,3-dihydro, and 2-methyl-4-vinylphenol provided precursors for FA and increased the total acidic groups to 14.06 mmol/g. In practical applications, artificial FA has also demonstrated its ability to regulate the absorption of cadmium by plants. In addition, the prepared artificial FA has a relatively high content of hydroxyl and carboxyl groups, which may have strong electron transfer and metal binding abilities. Suitable for various applications in sustainable agriculture and biomass directed conversion.