Extraction of cellulose nanocrystals (CNCs) from wastes is a valuable strategy from the environmental and economical points of view. Herein, a novel and cost-effective method for the preparation of superhydrophobic, environmentally friendly, and recyclable bio-aerogel by freeze-drying the aqueous suspension of CNCs extracted from waste tissue paper and polyvinyl alcohol (PVA) in the presence of hydrolyzed tetraethyl orthosilicate (TEOS) sol has been developed for the first time. The highly porous (98.42 %), ultralow density (0.017 g/cm³), and superhydrophobic (WCA of 154.93°±4.14) CNCs/PVA/TEOS aerogel can selectively remove oily contaminants from water (BET surface area of 76 m²/g). The aerogel showed a high sorption capacity in the range of 69−168 g/g for 6 oils and 8 organic solvents. The reusability experiments showed the aerogel could maintain more than 92 % of its sorption capacity even after 20 cycles of sorption-squeezing. The cyclic compressive stress-strain tests confirmed the good mechanical properties of the aerogel with 89 % of shape recovery after 50 cycles. The CNCs/PVA/TEOS aerogel can be used as a recyclable sorbent for removing oils/organic solvents from water.

从环境和经济的角度来看，从废物中提取纤维素纳米晶体 (CNC) 是一种有价值的策略。在此，一种新颖且经济高效的方法，通过在水解原硅酸四乙酯存在下冷冻干燥从废纸巾和聚乙烯醇 (PVA) 中提取的 CNCs 的水悬浮液来制备超疏水、环保和可回收的生物气凝胶(TEOS) sol 是首次开发。高度多孔 (98.42 %)、超低密度 (0.017 g/cm ³ ) 和超疏水性 (WCA 为 154.93°±4.14) CNCs/PVA/TEOS 气凝胶可以选择性地去除水中的油性污染物（BET 表面积为 76 m ²/g)。气凝胶对 6 种油和 8 种有机溶剂显示出 69-168 g/g 的高吸附容量。可重复使用性实验表明，即使经过 20 次吸附-挤压循环，气凝胶仍能保持其吸附能力的 92% 以上。循环压缩应力-应变测试证实了气凝胶的良好机械性能，50 次循环后形状恢复率为 89%。CNCs/PVA/TEOS 气凝胶可用作可回收的吸附剂，用于去除水中的油/有机溶剂。