Lotfy Vivian F, Basta Altaf H
Cellulose and Paper Department, National Research Centre, Dokki-12622, Giza, Egypt.
Cellulose and Paper Department, National Research Centre, Dokki-12622, Giza, Egypt.
Int J Biol Macromol. 2024 Dec;282(Pt 4):137126. doi: 10.1016/j.ijbiomac.2024.137126. Epub 2024 Oct 31.
The current study focuses on finding an ecological method to dispose of black liquors (BLs), containing lignin macromolecules, which are produced as byproducts of rice straw-based paper production. In addition to maximizing their value as precursors in the preparation of novel formaldehyde scavengers to avoid the environmental risks associated with using urea formaldehyde in agro-wood composites. To optimize the route, various black liquors are prepared from pulping of rice straw by different pulping agents (alkali, neutral, acidic and kraft reagents) used as additions or precursors for carbon compounds. Elemental analysis, thermogravimetric analysis [TGA], Fourier transform infrared [FTIR] and scanning electron microscope (SEM), are the techniques used to characterize the BLs; while the gel time, bond strength, and differential scanning calorimetry (DSC) methodologies are applied to determine the impact of black liquor (BL) and black liquor‑carbon nanostructures (BL-CNSs) on performance of urea formaldehyde (UF) adhesive. The behavior of the investigated BL-CNSs as HCHO-scavengers is assessed from their affinity to capture the HCHO, and reduction of free-HCHO in UF-palm fibers agro-composites. BL-CNSs, as novel scavengers, exhibit promising properties where the bonding strength of BL-CNSs-UF adhesives increased to 19.7 MPa even though the UF was only 8.4 MPa. Moreover, the formaldehyde adsorption capacity ranges from 35.4 to 63.6 mg/g as well as lowering the gel time. It is interesting to note that the investigated scavengers not only reduced the free-HCHO of composites by about 40-91 %, but also enhancement in their mechanical and water resistance properties; where the modulus of rupture (MOR), internal bond (IB) and reduction in thickness swelling improved to about 50 % and 83.3 %, and 38.8 %, respectively. According to the American National Standards Institute (ANSI) standard these new scavengers, especially from BL of neutral pulping, permit the production of an eco-board (E1) with static bending exceeding the H-3 class.
当前的研究聚焦于寻找一种生态方法来处理黑液（BLs），这些黑液含有木质素大分子，是稻草造纸生产过程中产生的副产品。除了将其作为制备新型甲醛清除剂的前体以实现价值最大化外，还可避免在农林复合材中使用脲醛所带来的环境风险。为优化该途径，通过使用不同的制浆剂（碱、中性、酸性和硫酸盐试剂）对稻草进行制浆来制备各种黑液，这些制浆剂用作碳化合物的添加剂或前体。元素分析、热重分析（TGA）、傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）是用于表征黑液的技术；而凝胶时间、粘结强度和差示扫描量热法（DSC）方法则用于确定黑液（BL）和黑液 - 碳纳米结构（BL - CNSs）对脲醛（UF）胶粘剂性能的影响。从所研究的BL - CNSs捕获甲醛的亲和力以及降低UF - 棕榈纤维农林复合材料中游离甲醛的能力来评估其作为甲醛清除剂的行为。作为新型清除剂，BL - CNSs表现出令人期待的性能，尽管UF胶粘剂的粘结强度仅为8.4 MPa，但BL - CNSs - UF胶粘剂的粘结强度提高到了19.7 MPa。此外，甲醛吸附容量在35.4至63.6 mg/g之间，同时还缩短了凝胶时间。值得注意的是，所研究的清除剂不仅使复合材料中的游离甲醛降低了约40 - 91%，还提高了其机械性能和耐水性；其中断裂模量（MOR）、内结合强度（IB）以及厚度膨胀率的降低分别提高到了约50%、83.3%和38.8%。根据美国国家标准学会（ANSI）标准，这些新型清除剂，尤其是中性制浆黑液中的清除剂，能够生产出静曲强度超过H - 3级的生态板（E1）。
