Simple preparation of biodegradable, superhydrophobic, and antifungal cellulose filter paper for efficient oil/water separation.

This study aimed to produce "green" and superhydrophobic filter paper with antifungal and oil-water separation capabilities. The process involved coating a sodium alginate/hydroxyapatite/natamycin (ALG-HA-NA) solution onto a commercial filter paper using a simple vacuum filtration method, followed by CaCl2 crosslinking and beeswax treatment under ambient conditions. Fourier transform infrared spectroscopy, X-ray diffraction scanning electron microscopy, and water contact angle (WCA) measurements revealed that the ALG-HA-NA-1@C paper displayed a dense and uniform coating with sufficient roughness, suggesting that the prepared paper became superhydrophobic (WCA = 154.8°). Furthermore, the ALG-HA-NA-1@C paper showed exceptional oil-water separation performance for oil-water mixtures and emulsions, in addition to self-cleaning and water resistance properties. Moreover, this superhydrophobic paper demonstrated strong chemical and mechanical durability. According to the agar disc diffusion assay, ALG-HA-NA-1@C paper showed antifungal activity against both A. niger and P. brevicompactum, which in turn inhibited the growth of biofilms on its surface. The release of NA mass by immersing the ALG-HA-NA-1@C sample in water was fitted to a zero-order kinetic model, exhibiting a diffusion coefficient of 3.43 × 10-10 cm2 s-1. The proposed approach offers an alternative perspective for the fabrication of superhydrophobic paper for environmental remediation and oil spill cleanup.