Functionally active membranes made of cellulosic microfibers (CMFs) have emerged as promising sorbents for the removal of nano-sized pollutants from water. The adsorption efficiency of these membranes has been increased through surface functionalization of pristine-CMFs using various chemistries. Still, until now, the produced materials consist of highly dense 2D networks that make the membranes inadequate as filters because of the very short interlayer spacing. Here, we report on novel tuned CMF functionalization procedures, namely carboxylation, phosphorylation, and methylation, that can overcome this problem by modulating the interlayer separation in the 2D membranes. To test our approach, fabricated nanolaminate membranes with grafted functional groups were subjected for the separation of metal ions, a dye and two drugs, and their separation efficiencies are being correlated with the degree of functionalization and tuned intercapillary spacing.