Shulga Galia, Neiberte Brigita, Kudrjavceva Valerija, Verovkins Anrijs, Viksna Arturs, Vitolina Sanita, Brovkina Julija, Betkers Talrits
Latvian State Institute of Wood Chemistry, Dzerbenes 27, LV-1006 Riga, Latvia.
Faculty of Medicine and Life Sciences, Latvian University, Jelgavas 1, LV-1004 Riga, Latvia.
Polymers (Basel). 2025 May 23;17(11):1455. doi: 10.3390/polym17111455.
Various pretreatment methods, often employed in wood biorefineries, aim to disrupt the wood architecture, thereby enhancing the efficiency of hemicellulose extraction for increasing the production of bio-ethanol, bio-gas, and bio-oil, as well as improving the pulping process. Pretreatment for the pulping process has advantages such as enhanced yield in biorefined products and reducing chemicals and energy consumption. This study examined the effect of an alkaline hydrolysis of birch sawdust on the chemical composition, aggregation ability, and surface activity of soda lignin obtained by soda pulping. The alkaline hydrolysis of birch sawdust led to a remarkable removal of hemicellulose and reduced its mechanical strength. The resorption of lignin fragments on the lignocellulosic matrix during the hydrolysis was observed. The soda pulping of the original and the treated sawdust was carried out under laboratory conditions at 165 °C for 90 min, using 4.5% sodium hydroxide. A higher yield of soda lignin and pulp was obtained from the treated sawdust. The reduced content of acidic and methoxyl groups in the chemical composition of the soda lignin from the hydrolyzed sawdust was explained by the predominance of polycondensation reactions in forming its primary structure. The changes in size and zeta potential values of the formed lignin particles, as well as in the modality of the size distribution with decreasing pH, were studied. The early-proposed suggestion about the existence of structural complementarity in the formation of the ordered lignin supermolecular structures has been testified. The higher surface activity at the air-water interface for the soda lignin extracted from the hydrolyzed sawdust, compared to the lignin from the original residue, was mainly attributed to a lower content of the acidic groups in its chemical composition, shifting the hydrophilic-hydrophobic balance of its structure toward hydrophobicity.
木材生物精炼厂经常采用的各种预处理方法旨在破坏木材结构，从而提高半纤维素提取效率，以增加生物乙醇、生物气和生物油的产量，并改善制浆工艺。制浆工艺的预处理具有提高生物精炼产品产量、减少化学品和能源消耗等优点。本研究考察了桦木锯末碱性水解对碱法制浆所得碱木质素的化学组成、聚集能力和表面活性的影响。桦木锯末的碱性水解导致半纤维素显著去除并降低了其机械强度。观察到水解过程中木质素片段在木质纤维素基质上的再吸附。在实验室条件下，使用4.5%的氢氧化钠，在165℃下对原始锯末和处理后的锯末进行90分钟的碱法制浆。处理后的锯末获得了更高的碱木质素和纸浆产量。水解锯末所得碱木质素化学组成中酸性和甲氧基含量降低，这是由于在形成其初级结构时缩聚反应占主导地位。研究了形成的木质素颗粒的尺寸和zeta电位值的变化，以及随着pH值降低尺寸分布模式的变化。关于有序木质素超分子结构形成中存在结构互补性的早期提议得到了证实。与原始残渣中的木质素相比，水解锯末中提取的碱木质素在气-水界面具有更高的表面活性，这主要归因于其化学组成中酸性基团含量较低，使其结构的亲水-疏水平衡向疏水性转变。
