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 13 C 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.