Thermal Characteristics and Simulation of Enzymatic Lignin Isolated from Chinese Fir and Birch

Abstract

Lignin is one of the main components of the plant cell wall, and the thermal properties of in situ biomass lignin are crucial for the multi-scale modeling of biomass properties and the thermodynamic modeling of lignin. In this study, high yields of double enzymatic lignin (DEL) were successfully isolated from softwood Chinese fir (Cunninghamia lanceolate (Lamb.) Hook.) and hardwood white birch (Betula platyphylla Suk.) to represent the in situ wood lignin. Their thermal properties, including specific heat capacity, thermal conductivity, thermal stability, and thermal degradation kinetic parameters, were tested and simulated. The results showed that Chinese fir DEL has different chemical structural units and thermal properties than birch DEL. The specific heat capacities of Chinese fir DEL and birch DEL at 20 °C were 1301 and 1468 J/(kg·K), respectively, and their thermal conductivities were 0.30 and 0.32 W/(m·K). Their specific heat capacity and thermal conductivity showed a positive linear relationship over a temperature range of 20–120 °C. Chinese fir DEL had a better thermal stability and a higher carbon residue than birch DEL. The average activation energy and pre-exponential factor changed with the conversion rate, and their relationships were simulated using linear or quadratic equations in the conversion rate range of 0.02–0.60. A second-order reaction function was found to be the best mechanism function for DEL thermal degradation.

Physicochemical Insights into Enzymatic Polymerization of Lignosulfonates

“…Thus, pLS showed slightly higher heat capacity than LS. Generally, the c P value for the pLS granulate is in accordance with the literature. , …”

“…Generally, the c P value for the pLS granulate is in accordance with the literature. 77,78 The polymerized material becomes insoluble in water, which makes it promising for various applications. However, as it turned out, it is also very resistant to organic solvents, hampering further characterization of the polymers.…”

Hot Compression of Calcium Chloride and Sodium Carbonate Modifies Wood for Tsoongiodendron odorum

“…The scanning electron microscope (SEM) comparison of the surface and middle parts (Figure 5) revealed that the surface cell wall was compressed and deformed, while the middle cell wall was almost intact and not compressed. Wang's periodic hot pressing densification SEM images of Chinese fir showed that the early and late wood cell walls and wood rays experienced varying degrees of deformation and distortion [25], indicating that traditional physical compression compressed the entire plate and significantly reduced the volume. The profile density distribution in our study (Figure 4) showed that the surface density was significantly higher than the middle density, demonstrating a high outside and low inside' density distribution resulting from the formation of calcium carbonate that increased the test material's density.…”

Preparation and characterization of lignin-derived carbon aerogels

“…Active free radicals containing benzene rings are formed, and these can easily react with other molecules or free radicals to generate macromolecules with more stable structures, eventually forming biochar at higher temperatures ( Chen et al, 2022 ). These conclusions were drawn from studies on thermal properties, including thermal stability, and thermal degradation kinetics of lignin ( Wang et al, 2022 ). The pyrolysis process of lignin is dominated by the condensation reaction and degradation and rearranging of smaller structural units within it.…”