双醛改性纤维素纳米纤丝增强木质素水凝胶及其耐温耐盐性能研究

Study on Lignin Hydrogel Reinforced by Dialdehyde-modified Cellulose Nanofibril and Its Temperature and Salt Tolerance

中文关键词:  木质素  水凝胶  双醛纤维素纳米纤丝  耐温耐盐  油田封堵

Key Words:lignin  hydrogel  dialdehyde cellulose nanofibril  temperature and salt tolerance  oil field plugging

中文摘要:

      将双醛纤维素纳米纤丝（DA-CNF）应用到木质素水凝胶的制备中，利用DA-CNF在水凝胶中的互穿网络作用以及醛基与碱木质素酚羟基发生缩合反应，从而达到增强木质素水凝胶强度的目的。傅里叶变换红外光谱（FT-IR）分析结果表明，聚乙二醇二缩水甘油醚（PEGDGE-500）以及DA-CNF与木质素发生了反应；扫描电子显微镜（SEM）分析结果表明，添加DA-CNF后，木质素水凝胶的结构呈多孔性；添加DA-CNF能够显著改善木质素水凝胶的物理强度、热稳定性和耐温耐盐性能，当DA-CNF添加量为2.0%时，木质素水凝胶拉伸应力由69 kPa提高至175 kPa，压缩应力由0.18 MPa提高至1.5 MPa，初始降解温度由209℃提高到248℃。DA-CNF增强的木质素水凝胶具有较高的耐温耐盐特性，在150℃、pH值=9的20万矿化度的盐水中老化20天后，其质量保留率仍可达86.4%，且具有较好的pH适应性。综上所述，DA-CNF增强的木质素水凝胶具有潜在的油田封堵应用潜力。

Abstract:

      The dialdehyde cellulose nanofibril （DA-CNF） was applied to the preparation of lignin hydrogel， and the interaction network of DA-CNF in the hydrogel and the condensation reaction between the aldehyde group and the phenol hydroxyl group in alkali lignin could enhance the strength of lignin hydrogel. Fourier transform infrared spectoscopy （FT-IR） results showed that poly（ethylene glycol） diglycidyl ether （PEGDGE-500） and DA-CNF reacted with lignin. Scanning electron microscope （SEM） analysis showed that adding DA-CNF rendered a porous structure of lignin hydrogel and improved its physical strength， thermal stability， and temperature and salt tolerance. The tensile strength of lignin hydrogel increased from 69.0 kPa to 175 kPa， compressive stress from 0.18 MPa to 1.5 MPa， and initial degradation temperature from 209°C to 248°C after adding 2.0% DA-CNF. The results of high temperature and high salt aging test showed after aging at 150℃ in saline water with pH value of 9 and salinity of 200000 for 20 days， the quality retention rate of DA-CNF reinforced lignin hydrogel could keep at 86.4% and it possessed good pH adaptability. Therefore， the DA-CNF reinforced lignin hydrogel has potential application in oil field plugging.