Dan Hongbing, Gao Yue, Wei Xianxiao, Yue Qinyan, Gao Baoyu
Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, 250100, China.
Environ Sci Pollut Res Int. 2025 Jan;32(1):43-55. doi: 10.1007/s11356-024-35745-x. Epub 2024 Dec 12.
Benefiting from its abundance, eco-friendliness, and sustainability, crop straw is considered a promising candidate combined with graphene oxide (GO) to fabricate straw-based graphene aerogels (SGAs) for oil/water separation. However, considering the complex composition of straw, the roles played by different crude fibers in straw in the formation of SGAs are still unclear. Herein, wheat straw (WS) was used in this work and pretreated with acid and alkali to regulate its crude fiber fractions. Then, it was crosslinked with GO to fabricate various SGAs for comparing their differences in the formation, structure, and oil/water separation performance. Results indicated that acid can remove plentiful hemicellulose from the WS (from 29.9 ± 2.1 to 7.0 ± 0.8 wt%) while retaining most lignin and cellulose; alkali can retain cellulose (from 32.4 ± 3.6 to 70.6 ± 1.3 wt%) while greatly removing lignin and hemicellulose. Ascribed to high BET surface area and porous structure, the graphene aerogels formed by acid-/alkali-treated WS demonstrated superior oil absorption capacity (AC-WSGA: 62.3-126.0 g/g and AL-WSGA: 66.3-125.2 g/g). The poor mechanical compressibility of AC-WSGA was caused by the high lignin residue (16.2 ± 0.7 wt%) in AC-WS. The maximum compressive stress for AL-WSGA under 60% strain was 1.6 kPa, ensuring it achieved recoverable oil-absorbing properties by extrusion. The above findings suggested that cellulose and hemicellulose in straw contributed to the formation of SGAs with abundant porous and compressible architecture, whereas the presence of lignin greatly increased the brittleness of SGAs and decreased their oil removal and recycling performances.
作物秸秆因其丰富性、生态友好性和可持续性，被认为是与氧化石墨烯（GO）结合制备用于油水分离的秸秆基石墨烯气凝胶（SGA）的理想候选材料。然而，考虑到秸秆成分复杂，秸秆中不同粗纤维在SGA形成过程中所起的作用仍不明确。在此，本研究使用小麦秸秆（WS），并对其进行酸碱预处理以调节粗纤维含量。然后，将其与GO交联制备各种SGA，以比较它们在形成、结构和油水分离性能方面的差异。结果表明，酸可从WS中去除大量半纤维素（从29.9±2.1降至7.0±0.8 wt%），同时保留大部分木质素和纤维素；碱可保留纤维素（从32.4±3.6增至70.6±1.3 wt%），同时大量去除木质素和半纤维素。由于具有高比表面积和多孔结构，经酸碱处理的WS形成的石墨烯气凝胶表现出优异的吸油能力（AC-WSGA：62.3 - 126.0 g/g和AL-WSGA：66.3 - 125.2 g/g）。AC-WSGA较差的机械压缩性是由AC-WS中高含量的木质素残留（16.2±0.7 wt%）导致的。AL-WSGA在60%应变下的最大压缩应力为1.6 kPa，确保其通过挤压实现可回收的吸油性能。上述研究结果表明，秸秆中的纤维素和半纤维素有助于形成具有丰富多孔和可压缩结构的SGA，而木质素的存在则大大增加了SGA的脆性，并降低了它们的除油和循环性能。
