Vásquez Lía, Campagnolo Laura, Athanassiou Athanassia, Fragouli Despina
Smart Materials , Istituto Italiano di Tecnologia , via Morego 30 , 16163 Genova , Italy.
Dipartimento di Chimica e Chimica Industriale (DCCI) , Università degli Studi di Genova , Via Dodecaneso 31 , 16146 Genova , Italy.
ACS Appl Mater Interfaces. 2019 Aug 21;11(33):30207-30217. doi: 10.1021/acsami.9b07907. Epub 2019 Aug 7.
Herein, expanded graphite is successfully combined with waterborne polyurethane to develop porous foams with underwater oleophobic properties for the separation of surfactant-free, oil-in-water mixtures and emulsions. To obtain foams with different pore sizes and therefore with different performances in the oil-water filtration process, two solvent-free fabrication processes are adopted. In the first one, the expanded graphite granules are mixed with the waterborne polyurethane (PUEGr), and in the second method, calcium carbonate is introduced to the two-component mixture (PUEGr_t). In both cases, the obtained foams exhibit hydrophilicity and oleophilicity in air and oleophobicity underwater, and they have porous interconnected networks, while their pore size distribution differs significantly. The foams can be used as 3D filters, able to separate, through gravity, surfactant-free, oil-in-water mixtures (10% w/w oil in water) with high oil rejection efficiencies and flow rates that depend on the type of foam. In particular, in the gravity-driven filtration process using 100 mL of the feed liquid, the PUEGr foams have an oil rejection efficiency of 96.85% and flow rate of 9988 L m h, while for the PUEGr_t foams the efficiency is higher (99.99%) and the flow rate is lower (8547 L m h) due to their smaller pore size. Although the PUEGr_t foams have slower separation performance, they are more efficient for the separation of surfactant-free emulsions (1% w/w oil in water) reaching an oil rejection efficiency of 98.28%, higher than the 95.66% of the PUEGr foams of the same thickness. The foams can be used for several filtration cycles, as well as in harsh conditions without deteriorating their performance. The nature of raw materials, the simple solvent-free preparation method, the effective gravity-driven filtration even in harsh conditions, and their reusability suggest that the herein engineered foams have great potential for practical applications in oil-water separation through highly energy-efficient filtration.
在此，膨胀石墨成功地与水性聚氨酯结合，开发出具有水下疏油性能的多孔泡沫，用于分离无表面活性剂的水包油混合物和乳液。为了获得具有不同孔径、从而在油水过滤过程中具有不同性能的泡沫，采用了两种无溶剂制备工艺。第一种方法是将膨胀石墨颗粒与水性聚氨酯混合（PUEGr），第二种方法是将碳酸钙引入两组分混合物中（PUEGr_t）。在这两种情况下，所得泡沫在空气中表现出亲水性和疏油性，在水下表现出疏油性，并且具有多孔互连网络，而它们的孔径分布有显著差异。这些泡沫可用作三维过滤器，能够通过重力分离无表面活性剂的水包油混合物（水中含10% w/w油），具有高的除油效率和取决于泡沫类型的流速。特别是，在使用100 mL进料液的重力驱动过滤过程中，PUEGr泡沫的除油效率为96.85%，流速为9988 L m h，而对于PUEGr_t泡沫，由于其孔径较小，效率更高（99.99%），流速更低（8547 L m h）。尽管PUEGr_t泡沫的分离性能较慢，但它们对于分离无表面活性剂乳液（水中含1% w/w油）更有效，除油效率达到98.28%，高于相同厚度的PUEGr泡沫的95.66%。这些泡沫可用于多个过滤循环，以及在恶劣条件下使用而不会降低其性能。原材料的性质、简单的无溶剂制备方法、即使在恶劣条件下也有效的重力驱动过滤以及它们的可重复使用性表明，本文设计的泡沫在通过高能效过滤进行油水分离的实际应用中具有巨大潜力。
