Cellulose acetate membranes treated with titanium dioxide and cerium dioxide nanoparticles and their nanocomposites for enhanced photocatalytic degradation activity of methylene blue

We report on the photocatalytic degradation activity of methylene blue (MB) using Cellulose acetate (CA) membranes embedded by metal oxide nanoparticles (NPs). Titanium dioxide and Cerium dioxide (TiO₂ and CeO₂) and their nanocomposites are used as nanofillers in CA membranes to enhance photocatalytic activity. The casted nanocomposite membranes are synthesized using the phase inversion method and characterized using X-ray diffraction, X-ray fluorescence, scanning electron microscopy, Fourier-transform infrared spectroscopy, and UV–Vis to investigate structural, surface morphological, elemental content, and the optical properties. In particular, surface morphological and optical results are analyzed to elucidate a deeper understanding of porosity and photocatalytic activity via the degradation of the MB dye. The as-prepared CA–NP membranes are tested for photocatalytic degradation of MB by exposing the membrane/MB dye combination to UV illumination for different exposure times. Results reveal that CA–TiO₂ membrane exhibits the smallest nanopore size, the most efficient exciton separation, and the largest surface area as compared with CA–CeO₂ and CA–TiO₂–CeO₂-casted membranes. Consequently, CA–TiO₂ membrane shows a good cyclic photocatalytic degradation activity (about 64%). Furthermore, the obtained MB degradation activity follows the increasing trend: CA–TiO₂ membrane (Energy gap \(\user2{E}_{{\mathbf{g}}} \, = \,3.26\,{\mathbf{eV}},\) Absorption activity \({\varvec{A}}\boldsymbol{\%}=64\boldsymbol{\%}\)) > CA–TiO₂–CeO₂ membrane (\({{\varvec{E}}}_{\text{g}}=3.33\,{\mathbf{eV}},\boldsymbol{ }{\varvec{A}}\boldsymbol{\%}=15\boldsymbol{\%}\)) > CA–CeO₂ (\({{\varvec{E}}}_{\text{g}}=3.4\,{\mathbf{eV}},\boldsymbol{ }{\varvec{A}}\boldsymbol{\%}=7\boldsymbol{\%}\)) that is directly correlated with the values of the \({{\varvec{E}}}_{\text{g}}\) of the NP component of the membranes, the high porosity, and large surface area of the membrane. This suggests the synergetic use of the two metal oxides in potential applications of the photocatalytic degradation of MB and other organic pollutants for water treatment.