Abstract In view of its chemical structure, lignin has recently become an interesting candidate for various applications. This work serves to optimize the isolation process of lignin from sugar industry by-product (bagasse can, molasses beet) applying alkali treatment. For this purpose, the effect of alkali and sulfuric acid concentrations have been studied ranging from 10% (w/v) to 20% (w/v) and 1.5 M–3 M, respectively. Moreover, the isolated lignins were characterized by different complementary analysis such as FT-IR and TGA/DTG. The aim behind this work is to reduce formaldehyde emissions and improving mechanical as well as physical properties of wood adhesive. Lignin was added with different ratios, as partial substitution, in urea-formaldehyde (UF) (5:95; 10:90; 13:87 and 15:85, w: w) and compared to commercial control UF (0:100). Furthermore, a theoretical calculation, using the density functional theory (DFT)/B3LYP method validated that the coniferyl alcohol (G), sinapyl alcohol (S) and paracoumaryl alcohol (H) can suck up on the energy of the orbital borders, electronic affinity, electronic chemical potential and thermodynamic properties. The results obtained showed that the efficiency of these molecules is influenced with different degrees by several descriptors. It was also found that the compounds G and S out of H studied were more efficient within the density functional theory (DFT) at the B3LYP/6–31 (d,p) computational level.

中文翻译：

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木质素-脲-甲醛木材胶粘剂的实验和理论研究：密度泛函理论分析

摘要 鉴于其化学结构，木质素最近已成为各种应用的有趣候选者。这项工作有助于优化采用碱处理从制糖工业副产品（甘蔗渣罐头、糖蜜甜菜）中分离木质素的过程。为此，研究了碱和硫酸浓度的影响，范围分别为 10% (w/v) 到 20% (w/v) 和 1.5 M–3 M。此外，分离的木质素通过不同的互补分析进行表征，例如 FT-IR 和 TGA/DTG。这项工作的目的是减少甲醛排放并改善木材粘合剂的机械和物理性能。在脲醛 (UF)（5:95；10:90；13:87 和 15:85，w:w）中添加不同比例的木质素作为部分取代，并与商业对照 UF (0:100) 进行比较. 此外，理论计算，使用密度泛函理论（DFT）/B3LYP方法验证了松柏醇（G）、芥子醇（S）和对香豆醇（H）可以吸收轨道边界的能量、电子亲和力、电子化学势和热力学性质。获得的结果表明，这些分子的效率受到几个描述符的不同程度的影响。还发现所研究的 H 中的化合物 G 和 S 在密度泛函理论 (DFT) 中在 B3LYP/6-31 (d,p) 计算水平上更有效。电子化学势和热力学性质。获得的结果表明，这些分子的效率受到几个描述符的不同程度的影响。还发现所研究的 H 中的化合物 G 和 S 在密度泛函理论 (DFT) 中在 B3LYP/6-31 (d,p) 计算水平上更有效。电子化学势和热力学性质。获得的结果表明，这些分子的效率受到几个描述符的不同程度的影响。还发现所研究的 H 中的化合物 G 和 S 在密度泛函理论 (DFT) 中在 B3LYP/6-31 (d,p) 计算水平上更有效。