Hydrophobic composite foams based on nanocellulose-sepiolite for oil sorption applications

TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl)-oxidized cellulose nanofibers (CNF) were assembled to fibrous clay sepiolite (SEP) by means of a high shear homogenizer and an ultrasound treatment followed lyophilization using three different methods: normal freezing, directional sequential combination both methods. Methyltrimethoxysilane (MTMS) was grafted the foam surface vapor deposition method introduce hydrophobicity resulting materials. Both SEP addition (for freezing methods) refreezing preparation procedure enhanced compressive strength foams, showing moduli in range from 28 103 kPa for foams loaded with 20% w/w sepiolite. Mercury intrusion porosimetry shows that average pore diameters 30–45 µm depending on method. This large porosity leads materials very low apparent density, around 6 mg/cm3, >99.5%. In addition, water contact angle measurement Fourier-transform infrared spectroscopy (FTIR) applied confirm hydrophobicity, which is suitable use as oil sorbent. The sorption ability these composite has been tested olive motor oils models organophilic liquid adsorbates, observing maximum capacity 138 90 g/g, respectively.