Dicarboxymethyl Cellulose‐Based Mixed‐Matrix Membrane Adsorbers: Preparation, Characterization, and Protein Retention Performance

This study reports, for the first time, the incorporation of dicarboxymethyl cellulose (DCMC) into mixed‐matrix membranes (MMMs). DCMC is a functionalized cellulose derivative with demonstrated adsorption of positively charged compounds. However, its incorporation into membranes has not previously been investigated. Polyethersulfone (PES) MMMs were prepared using dimethyl isosorbide as a green solvent via non‐solvent induced phase separation (NIPS) and a combined vapor‐induced phase separation (VIPS)‐NIPS approach, with varying DCMC filler concentrations. Characterization showed that all membranes possessed a similar morphology, comprising a denser top layer and a porous bottom layer, with finger‐like structures and macrovoids spanning the cross‐section. Pore size measurements varied from 0.14 to 0.43 μm, corresponding to the lower end of the microfiltration range. Filtration experiments using a model cationic protein demonstrated that DCMC incorporation enhanced separation efficiency through the introduction of carboxylic functional groups. The DCMC‐modified membranes achieved up to 80% retention of the model protein after six filtration cycles, attributed to electrostatic attraction between the filler and the model cationic protein. These findings demonstrate the feasibility of incorporating DCMC into membrane structures and provide proof of concept for the further development of DCMC‐based membranes for charge‐selective applications.