Table 3 Different oxidation approaches for lignin and biomass conversion for HS-like lignin material productions
From: Latest development in the fabrication and use of lignin-derived humic acid
Raw materials | Chemical/reagents used | Temperature (°C), time (min) | Carboxylic groups, mmol/g | Mw, g/mol | Application remarks | Refs. |
|---|---|---|---|---|---|---|
LS | NaOH, H2O2/air | 170–190, 180 | NA | NA | Transformed LS to HA (77 wt.% yields) | [59] |
LS | KOH, air/O2 | NA | NA | NA | Increased corn root dry weight and chlorophyll by 18% and 45%, respectively at 1Â mgC/L dose | [58] |
KL | KOH, O2 | 195, 30 | 2.6 | 3500–4000 | Increased fresh corn plant length, dry weight, and chlorophyll content by 27, 92 and 32%, respectively at 10 mgC/L dose | [144] |
KL | FeSO4, H2O2 | RT, 120 | NA | NA | Increased seeds germinations and two folds of chlorophyll contents in leaves at 860Â ppm dose | [131] |
Giant reed | KOH/H202 | 50, ON | NA | NA | Enhanced tomato seed germination and early hypocotyl growth by 10% at 10Â ppm | [157] |
Giant reed and Miscanthus | KOH, H202 | 50, ON | 1.02 | Â | Enhanced germination of maize seeds and root elongation increased by 50% at 10Â ppm dose | [154] |
Cardoon, Eucalyptus, and black poplar woods | NaOH, H202 | 50, ON | 0.4–1.4 | NA | Increased maize seedling growth by 72% at 10 ppm dose | [158] |