Insight into the Mechanism of Humic Acid’s Dissolution Capacity for Lignin in the Biomass Substrates

Abstract

The poor solubility of lignin in most solvents causes the biggest challenges in lignin valorization to improve overall biorefinery economics. In this work, humic acid (HA), a natural surfactant, was investigated with respect to its ability to assist in biomass delignification.After obtaining a baseline level of delignification using standard HA, a mechanism of action was proposed in which the lignin removal was driven by hydrophobic interactions. To explore this hypothesis, HA was modified in two ways. One batch was sulfonated to increase HA hydrophilicity, while the other was esterified to increase HA hydrophobicity. Treatment of the same substrates with the modified HA materials revealed that elevated hydrophobicity provided a further increase in the level of delignification. It was found that the solubility of lignin in the HA solution was increased with the enhancement of HA hydrophobicity from 12.2% (S-HA) to 16.8% (E-HA). Therefore, the initial hypothesis was confirmed that HA-derived delignification improvements appear to be a function of hydrophobic interactions. These results should aid further investigation into choosing surfactants (ideally those that are biobased) for utility in biorefinery processes.

Smooth Vetch (Vicia villosa var.) Coupled with Ball-Milled Composite Mineral Derived from Shell Powder and Phosphate Rock for Remediation of Cadmium-Polluted Farmland: Insights into Synergetic Mechanisms

“…Meanwhile, the peaks at 49.9° and 59.8° were associated with the P/Cd compound. For HA+BSPR treatment, the area of these peaks increased significantly, and a new peak appeared at 54.7°, demonstrating that Cd was converted into an insoluble precipitate under the combination of HA and BSPR …”

“…For HA+BSPR treatment, the area of these peaks increased significantly, and a new peak appeared at 54.7°, demonstrating that Cd was converted into an insoluble precipitate under the combination of HA and BSPR. 60 Besides, the contribution of CO 2 to Cd passivation was further investigated. As presented in Figure 7a, irrespective of the atmospheric conditions, the residual concentration of Cd(II) gradually declined with the extension of the reaction time.…”

Efficient depolymerization of lignin through microwave-assisted Ru/C catalyst cooperated with metal chloride in methanol/formic acid media

“…Developing renewable and environment-friendly energy has become an essential measure for many countries to promote energy transformation. Lignin, which constitutes up to 40% of the energy content of most terrestrial plants, shows great potential to produce liquid fuel or petroleum-based aromatic chemicals owing to its aromatic building blocks (Regalbuto, 2009;Barta et al, 2010;Cao et al, 2019;Ekielski and Mishra, 2020;Tang et al, 2022;Zhou et al, 2022).…”