Table 2.
Lignin valorization technique for value-added products with application
| Lignin valorization Technique | Products/Chemicals | Application | References |
|---|---|---|---|
| Reductive conversion | Aromatic phenols, Alcohols, Aldehydes, Acids and Alkyl phenols | Bio-based chemicals, additives, precursors for fragrances, vanillin, solvents, bio-based precursors, Feedstock for chemicals, biodegradable plastics | Cao et al. 2019; Grossman and Vermerris 2019 |
| Catalytic halogenation | Benzene, Toluene, Xylene | Bio-oil and fuel production | Mukarakate et al. 2022 |
| Hydrolytic depolymerization | Bio based polyurethenes (PU) | Bio-based foams, coatings, adhesives | Ma et al. 2023 |
| Catalytic depolymerization | Phenolic resins | Used in different coatings, composites, adhesives, insulations, lamination, wood bonding, in molded parts, and as plywood adhesives | Solt et al. 2018 |
| Oxidative conversion | Vanillin | Flavoring agent, used in perfumes and cosmetics, in pharmaceuticals | Wang et al. 2019a, b |
| Oxidative conversion | Syringaldehyde | Additives in polymers, food preservation | Wang et al. 2019a, b |
| Fast pyrolysis | Bio-oil | Fuel for combustion engines, feedstock for chemicals, soil fumigant, additive for asphalt and adhesives | Puziy et al. 2018; Yuan et al. 2022 |
| Pyrolysis | Syngas | Fuel for heat and electricity, feedstock for Fischer-Tropsch synthesis (produces liquid hydrocarbons) | Puziy et al. 2018; Yuan et al. 2022 |
| Physical or chemical activation of lignin | Activated carbon | Water and air filtration, gas purification, medicine (e.g., toxin adsorption), energy storage (supercapacitors) | Puziy et al. 2018; Yuan et al. 2022 |
| Electrospinning | Carbon fibers | Lightweight composites in aerospace, automotive parts, sports | Poursorkhabi et al. 2020; Puziy et al. 2018 |
| Electro chemical methods and reductive fractionation | 3D printing resin (Anionic surfactant), Lignin nano tubes, Hydrogels | Biodegradable filaments, smart packaging, tissue engineering, drug delivery, wound healing, controlled moisture release, food packaging, structural composites, nanocomposites | Jindal et al. 2023; da Cruz et al. 2022 |
| Electrospinning | Scaffolds | Tissue regeneration, bone repair, cell growth support, drug encapsulation, water filtration, agricultural applications | Ali et al. 2024a |
| Solvothermal techniques | Li-ion, Na-ion batteries, Supercapacitors | Electrodes, energy storage, charge storage, electrode materials | Culebras et al. 2019 |
| Photocatalytic and electrochemical conversion | Solar cells | Energy conversion, photovoltaic materials | Sultana et al. 2024 |
| Catalytic depolymerization, chemical modification | Bitumen, Cement additive | Soil conditioner, Fire retardant | Cao et al. 2019; Puziy et al. 2018 |
| Chemical depolymerization | Dispersant | In fertilizers and pesticides (controlled release agent, sequestering agent) | Cao et al. 2019; Puziy et al. 2018 |
| Biorefinery approaches and thermochemical method | Soil conditioner, Fertilizers and pesticides | Controlled release agent, sequestering agent, material absorbing soil contaminants | Brienza et al. 2024 |