Facile preparation of the superhydrophobic/superoleophilic polydopamine coated- polyurethane sponge by incorporating functionalized graphene oxide for efficient oil/water separation

The development of technology led to the development of a superhydrophobic/superoleophilic absorbent using polyurethane sponge modified with functionalized carbon nanostructures for the oil industry which can remove oily contaminants from oil/water mixtures and emulsion. As a result of the advance in technology and its impact in many fields, it is extremely crucial to eliminate the oil contaminant to purify the water content. A polyurethane (PU) sponge was dipped in the in-situ coating method by introducing an ultrathin polydopamine (PDA) layer and followed by functionalized graphene oxide with palmitic acid (GO-PA) insertion via ultrasonication and refluxing at 60 °C for 12 h. In addition, FTIR, SEM, EDX, XRD, and TGA results of the prepared nanocomposites indicated that chelating bonds between amine on PU-PDA surface, carboxylate, hydroxide on active modified GO surface area investigated the uniform distribution on the material surface. Fascinatingly, the water contact angle (WCA) measurement exhibited that PU-PDA- GO-PA nanocomposite showed a significant increase of the contact angles which was around 164°, while pure PU was 73° and material with the absence of PDA layer (PU-GO-PA) was 152°. After 20 cycles of material testing, the WCA steadily remained at 155°-152° indicating powerful superhydrophobic properties. For oil contact angle measurements, this modified material can immediately absorb the commercial oils and various organic solvents showing the excellent superoleophilicity with oil contact angle (OAC) was 0^o. Moreover, the performance of the modified material toward oil-water separation has been tested to observe the oil absorption capability, material reusability, efficiency, and permeate flux. The results have shown that by adjusting the surface roughness of the PU sponge, it could increase its capacity to absorb oil content such as heptane, toluene, cooking oil, and car lubricants. The modified material showed up to 53 times in oil absorption capability from its initial mass of PU, as well as up to 99.7 % in separation efficiency with permeate flux as high as 8000-9000 L.m^-1h^-2. More importantly, the sponge demonstrated excellent water- in-heptane emulsion separation and oil-water mixture separation for dyed oil removal within a few seconds. Hence, due to the PDA coating on the PU surface producing long-term performance, high mechanical, and thermal stability, the newly modified absorbents were proven to be capable of absorbing in a wide range of industrial applications with cost-effective and environmentally friendly characteristics. As a result, the PU-PDA-GO-PA nanocomposite has the huge potential to be a promising absorbent in a variety of industrial applications on account of its outstanding performance in various environmental issues.

Audience take-away:

• The audience can learn how urgent is water remediation topic.
• The audience can learn how the materials were chosen and prepared.
• The audience can notice that nanomaterial is an essential nowadays for many hot topics.
• The audience can know the excellent performance from the modified material for the oil/water separation process.
• The audience can investigate many promising/prospective materials to be found for solving the future problem.