Cellulosic sponges with pH responsive wettability for efficient oil-water separation

Area of Science:

• Materials Science
• Environmental Science
• Polymer Chemistry

Background:

• Efficient oil-water separation is crucial for environmental remediation and industrial processes.
• Developing responsive materials that can be controlled by external stimuli, such as pH, is an active area of research.
• Cellulosic materials offer a sustainable and abundant platform for creating advanced functional materials.

Purpose of the Study:

• To develop novel cellulosic porous materials with switchable wettability for efficient and controllable oil-water separation.
• To investigate the impact of alkylamine chain length on the pH-responsive behavior and separation performance.
• To evaluate the oil absorption capacity, selectivity, and reusability of the developed materials.

Main Methods:

• Cellulose acetoacetate sponges were synthesized and functionalized with alkylamines via dynamic covalent enamine bonds.
• Switchable wettability was achieved by controlling the pH, leading to reversible changes between superhydrophilic and hydrophobic states.
• Oil absorption, desorption, and separation efficiency for oil-water mixtures and emulsions were quantitatively assessed.

Main Results:

• The functionalized cellulosic sponges exhibited reversible switchable wettability from superhydrophilic (0°) to highly hydrophobic (146°) in response to pH changes.
• High and selective oil absorption capacities ranging from 40-80 g/g were achieved.
• Efficient separation of oil-water mixtures and emulsions with >99% efficiency was demonstrated, along with a 80% desorption ability.

Conclusions:

• pH-responsive cellulosic sponges with switchable wettability were successfully developed.
• These materials demonstrate excellent performance in controllable oil-water separation and oily wastewater purification.
• The combination of porous structure, tunable wettability, and environmental friendliness makes them promising for practical applications.