Phenolation can effectively improve the reactivity of lignin by directly increasing the phenolic hydroxyl groups and reactive sites for adhesive applications. Wheat straw residue isolated from an autohydrolysis/refining/enzymatic hydrolysis process was phenolated to improve the reactivity of lignin. The optimum phenolation conditions were determined to be a lignin/phenol (L/P) ratio of 1/3 with a 10% acid charge at 120 °C for 2 hours. Phenolated lignin resulted in 32 wt% of phenol incorporated onto lignin and a significant decrease in molecular weight. A comprehensive characterization indicated that all lignin substructures (β-O-4′, β-5′/α-O-4′, β-β′, ferulate, p-coumarate and p-benzoate) were reacted along with a hydrolysis of over 50% of polysaccharides during phenolation, resulting in a decrease in aliphatic hydroxyl groups and an increase in the phenolic hydroxyl groups. Phenol was incorporated onto both the sidechains and aromatic nuclei. These improvements in lignin reactivity will enable it to be used in adhesives with higher substitution rates.

Activated carbon fibers (ACFs) were successfully prepared from softwood lignin, which was isolated with polyethylene glycol 400 (PEG-400) as a solvolysis reagent, by water steam activation. The pore characterization and adsorption property of ACFs were investigated. The results showed that all the ACFs with more micropores exhibited high specific surface area and total pore volume which increased with the activation time prolonging; the highest ones were around 3100 m²/g and 1.5 mL/g, respectively. The specific surface area and total pore volume were much larger than those of other types of lignin-based ACFs and activated charcoal. Besides, with increasing activation time, the amount of graphitic carbon, which was the main compound on the surface of ACFs, decreased, while the amount of functional groups containing C–O slightly increased. In addition, the adsorption capacity of ACFs for methylene blue was highly increased as the activation time increased. Accordingly, lignin isolated with PEG is a promising precursor for ACF production.

Soda lignin does not have thermal flowing characteristics and it is impossible for it to be further thermally molded. To achieve the fusibility of soda lignin for fiber preparation by melt-spinning, an effective method for soda lignin modification was conducted by cooking it with polyethylene glycol (PEG) 400 at various ratios. The higher the ratio of PEG that was used, the more PEG molecular chains were grafted at the alpha carbon of the soda lignin through ether bonds, resulting in lower thermal transition temperatures and more excellent fusibility. The modified soda lignin with a weight ratio of lignin to PEG of 1:4 exhibited a relative thermal stability of molten viscosity at selected temperatures. Thereafter, the resultant fusible soda lignin was successfully melt-spun into filaments with an average diameter of 33 ± 5 μm, which is smaller than that of some industrial lignins. Accordingly, it is possible to utilize soda lignin to produce fibrous carbonaceous materials.

To develop more valuable application, oil palm trunk was successfully converted into activated carbon fibers (ACFs). An effective process of chemical treatment with dilute sulfuric acid was conducted to improve the thermal stability of primary fibers for further heating treatment. Carbon dioxide (CO₂) was used as activator to produce much porous structure with various pore diameter. The specific surface area (S_BET) and total pore volume (V_total) of resultant ACFs showed increasing trend as rise of activation temperature and time. The ACFs obtained under the temperature of 900 °C and time of 90 min exhibited highest S_BET and V_total, which were more than 1800 m²/g and 0.7 mL/g, respectively. Meanwhile, more graphic carbon on the surface of ACFs were destroyed with prolonging activation time, resulting in the oxygen-containing functional groups formed during activation process with CO₂. Due to the abundant pores and surface functional groups, the ACFs exhibited excellent adsorption capacity of chromium and would be an alternative material for industrial adsorption utilization.