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Highly Compressible and Hydrophobic Anisotropic Aerogels for Selective Oil/Organic Solvent Absorption
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posted on 2018-10-31, 00:00 authored by Xuexia Zhang, Hankun Wang, Zhiyong Cai, Ning Yan, Minghui Liu, Yan YuCellulose-based
aerogels show great potential as absorbents for
oil and chemical spill cleanup due to their low density and excellent
absorption capacity. However, the hydrophility and inferior mechanical
properties have often limited their practical applications. In this
study, high-performance biomass-based aerogels were prepared by freeze-casting
aqueous suspensions of polyvinyl alcohol and cellulose nanofibrils
in the presence of hydrolyzed methyltrimethoxysilane sol.
Successful silylation on the substrate surface was confirmed by Fourier
transform infrared spectroscopy, X-ray photoelectron spectroscopy,
thermal stability, and water contact angle measurements. Freeze-casting
successfully assembled a highly aligned interconnected porous structure,
resulting in the prepared aerogels with high modulus and strength
in the aligned direction (along the freezing direction) and outstanding
compression flexibility in the perpendicular direction (transverse
to the freezing direction). The ultralow density (10.2 kg/m3), high hydrophobicity (water contact angle of 140°), and good
compressive recovery (84% recovery of its original thickness after
100th compression tests) allow the aerogel to absorb oils and organic
solvents 45–99 times higher than its own weight. Meanwhile,
good reusability was also observed with an absorption capacity greater
than 84% after 35 absorption–squeezing cycles. The novel aerogels
prepared in this study are expected to have great potential for application
in treating oil and chemical spills.