Multifunctional Superwettable Material with Smart pH Responsiveness for Efficient and Controllable Oil/Water Separation and Emulsified Wastewater Purification

Abstract

Developing multifunctional superwettable materials is highly demanded in the oil/water separation field but remains challenging due to the critical limitations of complex fabrication strategy and high cost. Herein, based on the cost-effective kaolin nanoparticles, we present a convenient and mild strategy for fabricating a smart superwettable material with multiple excellent performances, such as pH-responsive water wettability, self-cleaning property, favorable buoyancy, and air purification performance. By virtue of the dual rough surface structure and special chemical composition, the resultant material surface exhibits a superior pH-dependent wettability, which can be reversibly switched between superamphiphobicity and superhydrophilicity–superoleophobicity for many times in accordance with the pH value of the corresponding aqueous solution. As a result, the obtained superwettable material with reversible and controllable water wettability can be applied in efficient and continuous separation of multiple types of oil/water mixtures, especially the highly emulsified oil/water emulsions, via in situ or ex situ wettability change. To our knowledge, the smart material with the wetting property of superamphiphobicity that can be used for continuous emulsified wastewater purification has been rarely discussed in the emerging research works. In addition, the as-prepared material presents universal applicability to diversiform substrates and exhibits robust durability and stability against high-concentration salt solutions and rigorous mechanical abrasion. All of these above-mentioned advantages indicate that the as-prepared superwettable material will hold great potential in various practical applications, including oily wastewater remediation, smart aquatic device fabrication, liquid droplet manipulation, guiding liquid movement, and optimizing multiple operations in industrial fields.

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

“…Compared with traditional single surface wettability oil/water separation materials, the smart membrane is a candidate material which can selectively separate the required liquid from the related oil/water mixtures. [20,33] Therefore, pH-responsive intelligent materials with adjustable wettability are expected to be widely used. In view of this, the prepared pH-controlled fabric was used to separate binary oil/water mixtures, as shown in Figure 7.…”

“…Therefore, it has the advantages of simplifying the separation device, reducing the separation energy consumption, saving the cost, etc., which are greatly beneficial to the development of the separation material in solving the oily wastewater. [20] With the rapid development of science and technology, the research on intelligent super-wetting materials is getting deeper and deeper. According to the stimulation of external environmental conditions, the intelligent super-wetting material changes the structure of the material surface, resulting in the change of wettability.…”

NaOH-Induced Fabrication of a Superhydrophilic and Underwater Superoleophobic Styrene-Acrylate Copolymer Filtration Membrane for Effective Separation of Emulsified Light Oil-Polluted Water Mixtures

“…Designing well-structured filtration materials, simultaneously acting as superhydrophilic and underwater superoleophobic surfaces, will provide an effective approach to separate (light) oil–water mixtures that result from their excellent selective affinity toward water or oil repelling. ,, Based on the Wenzel model, such a design should provide either a functional chemical composition or a special surface geometry. A proper chemical composition will provide the special functional groups to interact with or to repel the pollutant chemicals. − The surface geometry must contain a highly multi-scale porous rough architecture . The large pore size allows the fast permeation of liquid according to the Hagen–Poiseuille theory, whereas the submicron pore size effectively catches the highly emulsified pollutant droplets.…”

Development of Janus Cellulose Acetate Fiber (CA) Membranes for Highly Efficient Oil–Water Separation

“…Water and oil are important resources for people's production and development. However, in recent years, oil development has led to frequent offshore oil spills [1,2]. The traditional oil-water separation method requires a large area of equipment, high energy consumption and low-separation efficiency [3].…”