Water uptake capacity

The electrospun CA, CA/AC3.7, CA/AC5.5, and CA/AC6.7 composite nanofibers were further characterized by calculating their swelling and their ability to absorb water, which is essential for oil removal application. Approximately 0.1 g of CA/AC nanofiber composites was incubated at room temperature (24 ± 2 °C) for 24 h in three mediums of pH 3, 6, and 11 following the previous works of Shi et al. (2014) and Bhandari et al. (2017). The samples were softly dried using filter paper to get rid of the excess water and then weighed to obtain swelling weight (W_s). After that, the dry weight (W_d) was acquired by reweighing the swollen samples after drying them in an oven at 50 °C to a constant weight. This was done to get an accurate reading. Using the following Eq. (1), we could determine the product’s swelling ratio as a percentage. In this equation, W_S represents the weight of the swollen composite nanofibers, and W_d represents the weight of the dried composite nanofibers (Elmaghraby et al. 2022; Serag et al. 2018).