Fig. 1. Different magnifications (higher from left to right) of cross-sections SEM images of bare cellulose acetate membranes and membranes modified with GO, TPP, surfactant and their mixtures. The scale bars are: (a, d, g, j, m, s, v and y): 20 μm; (f, p and r): 10 μm; (b, e, h, i, k, l, n, t, w, z and zz): 2 μm; (o, u and x): 1 μm; (c): 200 nm; (q): 100 nm.
