Valorization of Lignocellulosic Waste (Crotalaria juncea) Using Alkaline Peroxide Pretreatment under Different Process Conditions: An Optimization Study on Separation of Lignin, Cellulose, and Hemicellulose

ABSTRACT

Lignocellulose materials, essentially consisting of lignin, cellulose and hemicelluloses, are abundant sources of fermentable sugars. The bast fiber of Crotalaria juncea (Sunn hemp), a native cover crop of India, was used as feedstock for this study. The primary objective of this study was to add value to the waste C. juncea bast fiber. The same was achieved by pretreating the waste fiber using alkaline peroxide solution at various process conditions. The optimal process condition for alkaline peroxide pretreatment was identified for the fiber to pretreatment solution (S/S) ratio of 1/40 at 50°C for 5h with respect to all response variables (lignin removal, hemicellulose recovery, recovery of solid pretreated material, and crystallinity of lignocellulose). Three-way ANOVA results revealed that S/S ratio had no significant effect; whereas, both temperature and time, and the combination of parameters, exhibited significant effect on response variables. The characteristic peaks associated with lignin and cellulose demonstrated a higher amount of lignin removal and increased cellulose content with elevated treatment time. Autoclave assisted pretreatment proved to be inefficient due to removal of lower amount of lignin in addition to higher hemicellulose degradation. On the other hand, pretreatment using ultrasound was found to be most effective in removing lignin, liberating hemicelluloses along with diminition in cellulose crystallinity.

摘要

木质纤维素材料，包括木质素、纤维素和半纤维素，是可发酵糖来源丰富。柽麻纤维的韧皮纤维（Sunn hemp），一个土生土长的印度覆盖作物为原料的研究。本研究的主要目的是向废物柽麻纤维；纤维增加价值。同样是通过预先在不同工艺条件下使用碱性过氧化氢溶液处理废旧纤维实现的。碱性过氧化氢预处理的最佳工艺条件确定纤维的预处理方案（S / S）5h相对于所有响应变量在50°C 1/40比值（去除木质素，半纤维素的回收，固体材料和预处理木质纤维素的结晶度恢复）。三单因素方差分析结果显示，S／S比值无显著影响，而温度和时间，以及参数的组合，表现出显著的响应变量，纤维素和木质素相关的特征峰，表明高量的木质素去除率与处理时间的增加，纤维素含量升高。较低的木质素去除率较高的半纤维素降解表明高压釜预处理效率低下的手段。另一方面，前处理采用超声发现去除木质素最有效的、解放的半纤维素在纤维素的结晶度。

KEYWORDS:

• Crotalaria juncea fiber
• alkaline peroxide pretreatment
• ultrasound-assisted pretreatment
• lignin content
• hemicellulose isolation
• crystallinity index

关键词:

• 柽麻纤维
• 碱氧化物预处理
• 超声辅助预处理
• 木质素的含量
• 半纤维素分离
• 结晶度指数

Supplementary material

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