A Fluoride‐Free and Super‐Wetting Functionalized‐Material with pH‐Responsiveness for Controllable Separation of Multiphase Oil/Water Mixtures

Abstract

Nowadays, oily wastewater seriously endangers human health and living environment. Intelligent materials with switchable wettability gear up the broad application prospect in controllable oil/water separation and have received extensive attention. Herein, a simple and novel fluoride‐free method for preparing pH‐responsive super‐wetting material by monomer polymerization is reported. Surprisingly, the as‐prepared smart material can produce reversible wettability changes between superhydrophobicity/superoleophilicity and superhydrophilicity/underwater superoleophobicity by adjusting various pH values. Based on this fresh phenomenon, it can be used to separate various oil/water mixtures on‐demand with high separation performance. It is worth noting that the smart fabric also separates mixtures of highly corrosive liquids and oils. Moreover, the smart fabric also has excellent self‐cleaning and low surface adhesion. In addition, it also shows excellent mechanical and chemical stability under harsh conditions. All these advantages show that the smart fabric can play a vital function in solving the related severe conditions of marine oil pollution and industrial wastewater.

Decoration of Cauliflower-Like TiO2 on Nanofibrous PVDF Membranes: A Strategy for Wastewater Treatment

“…The image of the emulsion before and after filtration is shown in Figure h. The model depicted in Figure i,j was utilized to better illustrate the separation mechanism of oil and water for the modified NF PVDF membrane. ,, The porosity and roughness of the membrane have a significant influence on how the liquid penetrates . The equation of intrusion pressure (Δ P ) can be written as normalΔ P = 2 γ normalL normalV R = prefix− C γ normalL normalV .25em normalc normalo normals .25em θ A where γ LV is the liquid (water or oil) and vapor interfacial tension, θ is the liquid CA on the modified NF membrane, R is the meniscus radius, C is the circumference of the membrane’s rough-structured interstice, and A is the interstice’s area of cross-sectional.…”

“…The durability of super wetting materials is an essential quality that defines the service life of materials in practical applications. 40 Therefore, to verify the long-term superhydrophobic durability of the NF TiO 2 @PVDF nano cauliflower-like membrane abrasion test was conducted. As a result, the WCA of the membrane decreases with the increment of the number of abrasion cycles shown in Figure 7a.…”

“…The in-air WCA on the membrane was obtained before and after to verify its durability. 40 For the ultrasonication test, the membrane was immersed in ethanol with ultrasonication treatment for 60 min. 41 The in-air WCA on the membrane was obtained at an interval of 15 min.…”

“…Thus, the chemical stability of the NF TiO 2 @PVDF nano cauliflower membrane was assessed by subjecting it to an acidic environment for 12 h before being exposed to alkaline, hot, and cold aqueous solutions for an additional 12 h each. 40,41 The membrane was rinsed with ultrapure water before being dried at 70 °C for 12 h. The in-air WCA on the membrane was obtained before and after to verify its chemical stability.…”

Multiple strategies to control the hydrophilic–hydrophobic balance of P(DMA-co-DMAEMA-co-QDMAEMA) coatings

“…The above results demonstrated the successful synthesis of PDDQ copolymers with different sulfonation ratios. In the FT-IR spectrum of PDDQ0, the stretching vibration peaks at 3431 cm −1 , 1728 cm −1 and 1150 cm −1 were observed to be assigned to the phenolic hydroxyl group in DMA, the ester group in DMAEMA and the quaternary ammonium group in DMAEMA, 42 respectively. The appearance of these three peaks suggested the successful polymerization of DMAEMA and DMA.…”