Table 1.
Advantages and disadvantages of lignin valorization methods
| valorization techniques | Feedstock | Advantages | Disadvantages | Biomass source and lignin recovery | References | |
|---|---|---|---|---|---|---|
| Biomass (Lignin%) | Extraction yield (%) | |||||
| Alkaline hydrolysis | Agricultural residuals: Rice straw, wheat straw, sunflower stalk | Operates under lower temperatures | Requires an expensive catalyst and the formation of inhibitors | De-oiled Jatropha waste (40–50%) | 93.4% | Novakovic et al. 2021; Oruganti et al. 2024 |
| Acid hydrolysis (dilute) | Wheat straw | Acid recycling is not required | High temperature and pressure are needed | Corn stover (17–21%) | 75.7% | Gill et al. 2021; Sheng et al. 2022; Tu and Hallett 2019 |
| Acid hydrolysis (concentrated) | Wheat straw and bagasse | Operates under mild temperatures | Acid recovery is expensive and requires corrosion-free equipment | Sugar cane (23.7%) | 91% | Ávila and Rosana 2022; Momayez et al. 2022 |
| Oxidative cleavage | Wheat straw, bagasse, and poplar sawdust | Effective lignin degradation | Expensive reagent requirement | Toonna sinensis branches (13%) | 77% | Lin et al. 2024; Wei et al. 2021 |
| Ionic liquid-assisted depolymerization | Wheat straw, bagasse and peanut | Sufficient dissolution | Expensive ionic liquids are required in higher amounts | Miscanthus x giganteus (17–25%) | 82% | Radhakrishnan et al. 2021; Taylor et al. 2024; Wang and Eika 2020 |
| Pyrolysis | Various lignin sources, such as dry impregnated lignin and agricultural residues | Simple and less-expensive | Higher temperature is required for the initiation of decomposition, which results in reduced yield of bio-oil | Tobacco waste (18.6%) | 85% | Lu and Gu 2022; Tan et al. 2024; Wang et al. 2023 |
| Microbial depolymerization by fungi | Rice straw, wheat straw, and softwood | Moderate conditions and minimal energy are sufficient, cost-effective | A wide sterile area, low hydrolysis rate, and more time are required | Sugarcane baggase (20–30%) | 87.6% | Dong et al. 2013; Giri and Sharma 2020; Hermosilla et al. 2018 |
| Microbial depolymerization by bacteria | Rice straw, wheat straw, and softwood | Moderate conditions are sufficient, cost-effective | Paper mill waste | 89% | Gu et al. 2024; Hemati et al. 2023; Kumar et al. 2022; Nurika et al. 2022 | |
| Enzymatic depolymerization | Rice straw, wheat straw, and softwood | Moderate conditions and minimal energy are sufficient | Paper mill waste | 90% | Kumar et al. 2022; Weiss et al. 2020; Zhang et al. 2021 | |