A cellulose sponge with robust superhydrophilicity and under-water superoleophobicity for highly effective oil/water separation

Abstract

A cellulose sponge with properties of superhydrophilicity and under-water superoleophobicity gives 99.94% separation efficiency in oil–water emulsion separation.

Facile fabrication of superhydrophilic membranes consisted of fibrous tunicate cellulose nanocrystals for highly efficient oil/water separation

“…Thus, the further enforcement of membrane was needless in the fabrication process, differing from other reported cellulose porous materials. [23] In addition, the oil contact angles for isooctane were 155, 154, and 154°, in NaCl (1M), HCl (1M), and NaOH (1M), respectively (Fig. S13), revealing that the TCNC membranes could tolerate acidic, salty, and alkaline environments.…”

“…These results revealed that hydroxyl groups on the surface of TCNCs made the membrane oleophobic, and the formation of cholesteric architecture in the membrane produced superoleophobicity. [23,24] On the other hand, the contact angle of water on the membrane under oil decreased from 132.7° to 31.6° with the increase of thickness of TCNC membranes, indicating the variation of wettability of membranes (from hydrophobicity to hydrophilicity), which will give them the ability to separate water-in-oil emulsion. We should emphasized that the wettability of TCNCs membrane was independent of membrane thickness after the nylon membrane was fully covered, and cholesteric architecture completely formed (dosage ≥ 0.73 g m -2 ).…”

“…[21,22] Moreover, different from carbon nanotubes, TCNCs might be superhydrophilic and underwater superoleophobic properties without any further modification, according to the wettability of cellulose based materials which has large amounts of hydroxyl groups on their surface. [23,24] Importantly, the fiber-like TCNCs can self-assemble to form chiral nematic membrane after removal of water from their suspensions. [25] The cholesteric or chiral nematic liquid crystal consist of stacked planes of rod-like unit aligned along a direction, with the orientation of each director rotated about the perpendicular axis from one plane to the next.…”

One-pot, template-free synthesis of a robust superhydrophobic polymer monolith with an adjustable hierarchical porous structure

“…7 However, the applied templates at one size scale usually produce porous materials containing single size scale pores, thus the combination of multiple templates strategies is necessary for hierarchical porous materials. 10,11 Herein, we report multifunctional polymer monoliths with hierarchical porosity without any template and further treatment which is green, simple and environment benign. 9 The fabrication of templates of special nanostructures and removal of hard templates lead to tedious procedure and inevitable limitations.…”

Advancement of Oil/Water Separating Materials: Merits and Demerits in Real-Time Applications

“…This is the first material which can separate oil/water from both layered and emulsion oil/water mixtures. Wang et al [71] reported a cellulose sponge with robust superhydrophilicity and under-water superoleophobicity for highly effective oil/ water separation. Smart surfaces are able to switch between superoleophilicity to superoleophobicity in presence of water on any other stimuli like pH or temperature.…”