Sodium dodecyl sulfate assisted electric field treatment for deproteinization of chitosan

Chitosan with a low protein residue is required as it is widely used in the field of biomedicine. Herein, we proposed a novel method for deproteinizing industrial grade chitosan via electric field treatment in a medium containing sodium dodecyl sulfate (SDS). The effects of electric field intensity, SDS concentration, and electrophoresis time on the protein removal efficiency were optimized by orthogonal experimental design and model building. Chitosan with an ultra-low protein residue (0.151 wt%) can be obtained at the voltage of 300 V, the SDS concentration of 1 wt%, and the electrophoresis time of 2 h. The strong binding between SDS and residue protein renders the conjugate with negative charges, which can migrate under the electric field. In addition, the electric field deproteinization process reduces the heavy metal content of chitosan slightly, while keeping the chemical structure of chitosan unchanged. The methodology provided in this work suggests the great potential of electric field treatment in removing residue protein in chitosan.