Production and characterization of dialdehyde cellulose through green and sustainable approach

The objective of this study was to develop the efficient methods for dialdehyde cellulose (DAC) production, in which periodate solution was used as oxidant, and an electrochemically assisted system was applied to achieve green, efficient, low-cost and sustainable oxidization of cellulose. The microcrystalline cellulose (MCC) was pre-treated by alkali or ultrasound, and then oxidized to prepare DAC in the electrolyzer with aqueous solution of sodium periodate. Finally, the DAC was obtained by centrifugation and lyophilization. The prepared DAC materials were characterized by FTIR, XRD and SEM, and analyzed via aldehyde group contents, crystallinity index, water solubility index and water retention value. The introduction of active functional groups promoted cellulose hydration and swelling. Compared to the ultrasound pretreatment, the alkaline pretreatment had a great influence on the water solubility index and water retention value of cellulose. The aldehyde group contents of DAC increased after the MCC was oxidized by sodium periodate in the electrolyzer. Electrochemically assisted oxidation significantly decreased the crystallinity of the DAC, and the surface structure was smooth and soft, which can be attributed to the electrochemically assisted reaction that could regenerate the spent periodate in anode electrolytic chamber. When DAC was prepared under optimal conditions (current density: 0.075 A/cm², periodate concentration: 0.6 mol/L, reaction time: 30 min), the regeneration efficiency of spent periodate reached about 93.4%.