A variety of protic ionic liquids (PILs) were utilized to extract lignin from black liquor (BL). The PILs and a control IL, [Emim][Ac], were evaluated to extract lignin under different conditions. The impact of temperature, time and the IL,PIL:BL were the factors evaluated for extracting lignin. [Eth][Ac] was successful in extracting 75.3 ± 3.4% of the lignin (dry-basis) from BL at 95 °C for a PIL:BL(20:1)(w:w) and a mixing time of 4.5 h. The lignin extracted (13.4 ± 0.5%) was lowest for [Pyrr][La] under the same conditions. The characterization of the extracted lignin by FTIR confirmed that the observed peaks for the extracted lignin were in agreement with the peaks for a standard lignin. The conditions for the lignin extracted from BL using [Eth][Ac] were optimized in a three-factor, three-level Box-Behnken design (BBD). The factors (levels) of optimization parameters included time (0.5 h, 4.0 h, 7.5 h), temperature (60 °C, 95 °C, 130 °C), and the PIL:BL (10:1, 15:1, 20:1)(w:w). The BBD data was employed to develop a quadratic prediction model for lignin extraction as a function of the parameters affecting the process. A comparison of the model prediction with the experimental data confirmed the model predicted values were correlated with the experimental results. The optimum lignin extraction of 70.0% predicted by the model was 5.0% less than the experimental value, 75.0 ± 2.9%. The experimental quantity of lignin extracted with [Emim][Ac] under the same conditions was 77.6 ± 2.1%. The study established that the lignin extraction using PIL is comparable with the acidification-based commercial extraction, such as LignoBoost® and LignoForce® for lignin extraction from BL.

多种质子离子液体 (PIL) 被用于从黑液 (BL) 中提取木质素。对 PIL 和对照 IL [Emim][Ac] 进行评估，以在不同条件下提取木质素。温度、时间和 IL,PIL:BL 的影响是评估提取木质素的因素。[Eth][Ac] 成功地从 BL 中提取了 75.3 ± 3.4% 的木质素（干基），在 95 °C 下，PIL:BL(20:1)(w:w) 和混合时间为 4.5 小时. 在相同条件下，提取的木质素 (13.4 ± 0.5%) 对于 [Pyrr][La] 是最低的。通过 FTIR 对提取的木质素进行表征证实，所观察到的提取木质素峰与标准木质素的峰一致。使用 [Eth][Ac] 从 BL 中提取木质素的条件在三因素、三水平 Box-Behnken 设计 (BBD) 中进行了优化。优化参数的因素（水平）包括时间（0.5 h、4.0 h、7.5 h）、温度（60 °C、95 °C、130 °C）和 PIL:BL（10:1、15:1、 20:1)(宽:宽)。BBD 数据用于开发木质素提取的二次预测模型，作为影响过程的参数的函数。模型预测与实验数据的比较证实模型预测值与实验结果相关。模型预测的最佳木质素提取率为 70.0%，比实验值 75.0±2.9% 低 5.0%。在相同条件下用[Emim][Ac]提取的木质素的实验量为77.6±2.1%。研究表明，使用 PIL 提取木质素与基于酸化的商业提取具有可比性，