Preparation and properties of pH-responsive reversible-wettability biomass cellulose-based material for controllable oil/water separation

Two novel pH-responsive reversible-wettability biomass cellulose-based materials of cellulose-g-PAA and cellulose-g-PAM were conveniently prepared by grafting acrylic acid (AA) and acrylamide (AM), respectively, onto eucalyptus pulp cellulose. The hydrophobic-oleophilic of cellulose-g-PAA and the oleophobic-hydrophilic of cellulose-g-PAM were converted to oleophobic-hydrophilic and hydrophobic-oleophilic, respectively, as the pH converted from 1 to 9. The pH-responsive mechanism of these cellulose-based materials was investigated by ¹³C nuclear magnetic resonance, X-ray photoelectron spectroscopy, and atomic force microscopy analyses. The resulting cellulose-g-PAA and cellulose-g-PAM papers were applied in the switchable separation of oil/water mixtures. Water passed through the cellulose-g-PAA paper at pH = 9 and cellulose-g-PAM paper at pH = 1, while oil was retained. After changing the pH value, oil permeated these papers, but water did not. The papers exhibited excellent regeneration performances; the oil adsorbed on the papers was completely desorbed via pH control.