Green fabrication of wheat straw-based lignin containing nanofibril aerogels as recyclable absorbents for oil-water separation

Abstract

Abstract Cellulose nanofibril (CNF) composite aerogels have been the focus of studies in organic solvent absorption and oil removal fields due to their low density, high absorption capacity, nontoxicity, and biodegradable properties. However, the complicated pretreatment process and increasing environmental concerns restrict the large-scale application of CNF-based materials. Herein, hydrophobic lignin-containing nanofibril (LCNF)/ polyvinyl alcohol (PVA) aerogels were prepared through freeze-drying and thermal chemical vapor deposition of methyl trichlorosilane (MTMS). The SEM and FT-IR results showed that modified LCNF/PVA (M-LCNF/PVA) aerogels incorporated a three-dimensional interpenetrating network structure and the hydrophobic siloxane coating was successfully prepared on the LCNF/PVA scaffold. The aerogel presented outstanding physical properties including a low density of 12.949 ± 0.402 mg/cm3, high porous of 98.99%, high flexibility, and enhanced compressibility due to the homogenous porous structure. The wettability test revealed that the aerogel, with a water contact angle (WCA) up to 146 ± 1.89°, was highly hydrophobic.The modified aerogel exhibited absorption capacity for various oil and organic solvents and the maximal adsorption capacity of M-LCNF/0.25PVA aerogel for chloroform can reach 106.80 ± 4.97 g/g aerogel. In addition, the modified aerogel is capable of separating emulsified water/oil mixtures, which broad its potential application. Notably, the aerogel demonstrated good reusability because it still maintained more than 61.44% of its original uptake capacity after 10 times extrusion cycle. The facile technique for the preparation of LCNFs from low-cost lignocellulosic biomass without a chemical bleaching process is green, sustainable, and can be used to fabricate high-efficiency LCNF-based sorbents from agricultural waste for oil and industrial organic solvent spills.