1. Kinetics of Lignin Separation during the Atmospheric Fractionation of Bagasse with p-Toluenesulfonic Acid
Baojuan Deng, Yadan Luo, Meijiao Peng, Tao Li, Jianwei Su, Yang Wang, Xuelian Xia, Chengqi Feng, Shuangquan Yao Int J Mol Sci. 2022 Aug 6;23(15):8743. doi: 10.3390/ijms23158743.
As a green and efficient component separation technology, organic acid pretreatment has been widely studied in biomass refining. In particular, the efficient separation of lignin by p-toluenesulfonic acid (p-TsOH) pretreatment has been achieved. In this study, the mechanism of the atmospheric separation of bagasse lignin with p-TsOH was investigated. The separation kinetics of lignin was analyzed. A non-simple linear relationship was found between the separation yield of lignin and the concentration of p-TsOH, the temperature and the stirring speed. The shrinking nucleus model for the separation of lignin was established based on the introduction of mass transfer and diffusion factors. A general model of the total delignification rate was obtained. The results showed that the process of lignin separation occurred into two phases, i.e., a fast stage and a slow stage. The results provide a theoretical basis for the efficient separation of lignin by p-TsOH pretreatment.
2. p-Toluenesulfonic acid combined with hydrogen peroxide-assisted pretreatment improves the production of fermentable sugars from walnut (Juglans regia L.) shells
Junjun Zhu, Ningxin Jiao, Haoran Li, Guangliu Xu, Han Zhang, Yong Xu Bioresour Technol. 2022 Jul;355:127300. doi: 10.1016/j.biortech.2022.127300. Epub 2022 May 10.
This study presents p-toluenesulfonic acid (p-TsOH) pretreatment combined with subsequent hydrogen-peroxide pretreatment for the fractionation of all lignocellulosic components from walnut shells (WNS). The main focus of this study is the production of fermentable sugars. During p-TsOH pretreatment (55% p-TsOH, 1:10 solid-to-liquid ratio, 90 °C, 120 min), 50.2% of lignin and 88.3% of xylan were dissolved. Subsequently, the p-TsOH pretreated WNS without washing (to reduce water consumption) was further pretreated with 40% (v/v) H2O2 and 74.6% of lignin was removed at 60 °C for 120 min. Compared with the glucose yield of 10.2% from p-TsOH pretreated WNS, the glucose yield from the p-TsOH/H2O2 pretreated WNS could be significantly improved to 94.4%. Structural characterization analysis showed increases in porosity, biomass disruption, and cellulose crystallinity during p-TsOH/H2O2 pretreatment. Mass balance demonstrated that 1000 g of WNS produced 295.1 g of fermentable sugars (263.6 g glucose and 31.5 g xylose).
3. Efficient separation of bagasse lignin by freeze-thaw-assisted p-toluenesulfonic acid pretreatment
Huali Zeng, Baojie Liu, Jiao Li, Mei Li, Meijiao Peng, Chengrong Qin, Chen Liang, Caoxing Huang, Xinping Li, Shuangquan Yao Bioresour Technol. 2022 May;351:126951. doi: 10.1016/j.biortech.2022.126951. Epub 2022 Mar 5.
Lignin separation is an important procedure that benefits multiple industries and in particular biomass transformation efforts. In this study, bagasse lignin was separated by freeze-thaw-assisted p-toluenesulfonic acid (p-TsOH) pretreatment. The optimal conditions were freezing temperature -60 °C, freezing time 8.0 h, thawing temperature 15 °C, p-TsOH concentration 60%, pretreatment temperature 70 °C, and time 20 min. Lower acid concentrations and temperatures were used compared with traditional p-TsOH pretreatment. The efficiency and selectivity of lignin separation were improved. It was attributed to freeze-thawing, which provided a more efficient physical channel for the effective penetration of p-TsOH. The separation, extraction and purity of lignin were improved to 89.76%, 78.22% and 77.89%, respectively. High separation, high extraction, high purity and large molecular weight lignin samples were obtained. In addition, the recovery and reuse of p-TsOH was enhanced. This provided a new method for the efficient and clean separation of lignin.
