Highly hydrophobic and superoleophilic agar/PVA aerogels for selective removal of oily substances from water

In this study, low-cost, environmentally friendly and porous agar/PVA aerogel sorbent materials with highly hydrophobic property were fabricated for the selective separation of oily substances and organic solvents from water by (i) the cross-linking reaction, (ii) freeze drying process and (iii) surface coating treatment. The characterization of agar/PVA aerogels was performed by water solubility, contact angle, SEM, EDX, mapping and XPS measurements. SEM and porosity results revealed that the increase of PVA amount within aerogel matrix led to a decrease in the pore structure of aerogel material. Agar/PVA (100:0) aerogel had good absorption capacity values (19.0-48.1 g·g^-1) for various oily substances and organic solvents. All aerogels had excellent separation efficiency (≥99.3%) for chloroform-water mixture. For chloroform-water mixture and emulsion, the flux value of agar/PVA (100:0) aerogel was found to be 4273 L·m^-2·h^-1 and 3094 L·m^-2·h^-1, respectively. New agar/PVA aerogels are promising materials for the effective separation of oil-water or organic solvent-water mixtures and the cleaning of oil-spills from water.