Fabrication of the superhydrophobic natural cellulosic paper with different wettability and oil/water separation application

Renewable superhydrophobic materials have attracted great attention due to their extensive applications in the fields such as cost-effective and biodegradable oil/water separation field. Herein, we reported an eco-friendly and facile methodology to develop the superhydrophobic cellulosic paper by immersion method using the ethanol solution of stearic acid. Furthermore, the treated cellulosic papers showed super-hydrophobicity with water contact angle (WCA) above 153 degrees. Interestingly, this method can realize superhydrophobic-hydrophilic conversion by simply adjusting the temperature and is amenable for different substrates and with the WCA of 114-162 degrees. More importantly, the utilization of fluorinated reagents has been avoided, thereby minimizing the production cost and improving safety and environmental aspects. Meanwhile, the modified natural cellulosic paper is applied for oil-water separation, and its separation efficiency was as high as 95% after 10 cycles, indicating the good reusability of stearic acid modified filter papers. Consequently, this simple strategy based on the stearic acid immersion method thus provided an easy conversion of superhydrophobic-hydrophilic interface and provided facile strategies for conversion of commercial quantitative filter paper to functional materials for oil/water separation.