Alkaline Pretreatment Facilitate Mechanical Fibrillation of Unbleached Cellulose Pulps for Obtaining of Cellulose micro/nanofibrils (MFC)

ABSTRACT

Energy expenditure is a limiting factor for the production of cellulose micro/nanofibrils in mechanical processing. This study evaluated the effect of novel alkaline pretreatments on unbleached Eucalyptus sp. pulps (hardwood) and Pinus sp. cellulose (softwood) to facilitate the production of cellulose nanofibrils by mechanical fibrillation and reduce the energy consumed by the mill. Pretreatments with NaOH in concentrations of 5% for 2 h and 10% for 1 h and 2 h and a hybrid pretreatment with 5%/16% NaOH/ H₂O₂ for 2 h were evaluated. The 10% pre-treatment was done at 1 h and 2 h to evaluate the effect of the less aggressive treatment (1 h). The morphology, chemical composition, turbidity of the fibers/suspensions, mechanical properties, fibrillation quality index and energy expended during the fibrillation were evaluated for each pretreatment. The less aggressive pretreatments produced micro/nanofibrils with fewer passes of the pulp through the fibrillator, which effectively facilitated extraction with lower energy consumption. The hybrid pretreatment did not show satisfactory results in reducing energy consumption, and the quality of the nanofibrils produced by this pre-treatment was inferior to the others. This study showed innovation in performing novel and efficient NaOH and hybrid (NaOH/H₂0₂) pretreatments on commercial unbleached pulps to obtain pulp micro/nanofibrils.

摘要

能量消耗是机械加工中生产纤维素微/纳米纤维的限制因素. 本研究评估了新型碱性预处理对未漂白桉树纸浆 (硬木) 和松树纤维素 (软木) 的影响, 以促进通过机械纤维化生产纤维素纳米纤维, 并减少磨机能耗. 评估了浓度为5%的NaOH预处理2 h, 浓度为10%的NaOH预处理1 h和2 h, 以及浓度为5%/16%的NaOH/H2O2混合预处理2 h. 在1小时和2小时进行10%预处理, 以评估攻击性较小的治疗 (1小时) 的效果. 对每种预处理的纤维/悬浮液的形态, 化学成分, 浊度, 力学性能, 成纤质量指数和成纤过程中消耗的能量进行了评估. 不太激进的预处理产生了微/纳米原纤维, 纸浆通过原纤维发生器的次数更少, 从而有效地促进了提取, 能耗更低. 混合预处理在降低能耗方面没有显示出令人满意的结果, 并且这种预处理所制备的纳米纤维的质量不如其他预处理. 本研究表明, 在对商业未漂白纸浆进行新型高效NaOH和混合 (NaOH/H202) 预处理以获得纸浆微/纳米纤维方面存在创新.

KEYWORDS:

• Cellulose nanofibers
• cell wall
• energy consumption
• microfibrillated cellulose (MFC)
• nanotechnology
• turbidity

关键词:

• 纤维素纳米纤维
• 细胞壁
• 能源消耗
• 微纤化纤维素 (MFC)
• 纳米技术
• 浊度

Highlights

• Obtaining cellulose micro/nanofibrils in pre-treated high-yield pulps.

• Obtaining cellulose micro/nanofibrils from unbleached commercial pulps.

• Pre-treatments reduced the energy consumption of unbleached pulps.

• Reduction of energy consumption by up to 40% in unbleached pulps

• Efficacy of alkaline pretreatments on commercial unbleached pulps to increase fibrillation index.

Acknowledgment

The authors are grateful for the financial support (133628/2017-5) provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Capes Brazil. Microscopy Center of the Federal University of Minas Gerais (http://www.microscopia.ufmg.br) to provide equipment and technical support for experiments involving transmission electron microscopy (MET).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15440478.2022.2092252