Facile Preparation of Robust Superhydrophobic/Superoleophilic TiO₂-Decorated Polyvinyl Alcohol Sponge for Efficient Oil/Water Separation

Abstract

Oily wastewater and oil spills pose a threat to the environment and human health, and porous sponge materials are highly desired for oil/water separation. Herein, we design a new superhydrophobic/superoleophilic TiO 2 -decorated polyvinyl alcohol (PVA) sponge material for efficient oil/water separation. The TiO 2 –PVA sponge is obtained by firmly anchoring TiO 2 nanoparticles onto the skeleton surface of pristine PVA sponge via the cross-linking reactions between TiO 2 nanoparticles and H 3 BO 3 and KH550, followed by the chemical modification of 1 H ,1 H ,2 H ,2 H -perfluorodecyltrichlorosilane. The as-prepared TiO 2 –PVA sponge shows a high water contact angle of 157° (a sliding angle of 5.5°) and an oil contact angle of ∼0°, showing excellent superhydrophobicity and superoleophilicity. The TiO 2 –PVA sponge exhibits excellent chemical stability, thermal stability, and mechanical durability in terms of immersing it in the corrosive solutions and solvents, boiling it in water, and the sandpaper abrasion test. Moreover, the as-prepared TiO 2 –PVA sponge possesses excellent absorption capacity of oils or organic solvents ranging from 4.3 to 13.6 times its own weight. More importantly, the as-prepared TiO 2 –PVA sponge can separate carbon tetrachloride from the oil–water mixture with a separation efficiency of 97.8% with the aid of gravity and maintains a separation efficiency of 96.5% even after 15 cyclic oil/water separation processes. Therefore, the rationally designed superhydrophobic/superoleophilic TiO 2 –PVA sponge shows great potential in practical applications of dealing with oily wastewater and oil spills.

Mussel-Inspired Durable TiO2/PDA-Based Superhydrophobic Paper with Excellent Self-Cleaning, High Chemical Stability, and Efficient Oil/Water Separation Properties

“…In addition, to characterize the mechanical durability of the TiO 2 /PDA-based superhydrophobic paper, water contact angles (WCAs) were tested after sandpaper abrasion tests for 30 cycles. That is, the TiO 2 /PDA-based superhydrophobic paper was pressed against the sandpaper (800 mesh) with a 100 g stainless steel weight and was pulled with a pair of tweezers at a speed of 0.1 cm/s …”

“…During the oil/water separation process, tetrachloromethane can easily permeate through the superhydrophobic paper into the beaker below, while the water will remain above the superhydrophobic paper. The separation efficiency is calculated by the weight of the oil where M a (g) and M b (g) are the weights of the oil before and after the process of oil/water separation, and η (%) is the separation efficiency of obtaining oil from water by the TiO 2 /PDA-based superhydrophobic paper . In addition, the emulsions (i.e., the content of water is 1 wt %) of water-in- n -hexane and water-in-tetrachloromethane were stabilized by Span-80 (0.1 wt %).…”

“…Frequent oil spill incidents and the discharge of industrial oily wastewaters cause significant threats to the ecological environment and human health. For example, the Deepwater Horizon oil spill in 2010 and the Bohai Bay oil spill in 2011 released tremendous amounts of crude oil into coastal waters, leading to catastrophic damage to marine organisms. , To remove toxic chemicals in oily wastewaters, traditional methods have been developed, including in situ burning, air flotation, chemical dispersion, and bioremediation. − However, these approaches suffer from potential secondary pollution, complex operations, high cost, and low separation efficiency. − Thus, it is necessary to explore more efficient methods for the treatment of oily wastewaters.…”

“…For example, the Deepwater Horizon oil spill in 2010 and the Bohai Bay oil spill in 2011 released tremendous amounts of crude oil into coastal waters, leading to catastrophic damage to marine organisms. 1,2 To remove toxic chemicals in oily wastewaters, traditional methods have been developed, including in situ burning, air flotation, chemical dispersion, and bioremediation. 2−4 However, these approaches suffer from potential secondary pollution, complex operations, high cost, and low separation efficiency.…”

Electro‐/Photo‐Thermal Promoted Anti‐Icing Materials: A New Strategy Combined with Passive Anti‐Icing and Active De‐Icing

“…[119] In real outdoor application, the self-cleaning property of photo-thermal promoted AIM is important for photo-thermal efficiency, for the contaminants (i.e., organic liquids and oils) can block and scatter the sunlight. [12,146,147] Wu et al proved that the photo-thermal effect under 1 sun can separately increase the temperatures of silica shell coated candle soot (SCS) to 14.5 °C and superhydrophobic PDMS brushes grafted SCS (PSCS) to 50 °C, which enhances the removal of contaminants by surface superhydrophobicity (Figure 8d1,d2). [12] Zhao et al studied the de-icing properties of smooth aluminum (S) (Figure 8e1), bionic hydrophilic aluminum (BH) (Figure 8e2) and bionic superhydrophobic aluminum (BS) (Figure 8e3) under the photo-thermal effect (1 sun), respectively.…”