Preparation of Dialdehyde Cellulose from Palm Date Pulp

The DAC was obtained by oxidative reaction of sodium metaperiodate on bleached cellulose (Figure 2). The preparation of DAC was performed according to a previously published method with minor modifications [62 (link)]. Briefly, pulp of palm date, 2 g was dispersed in 100 mL of distilled water and then 1.3 g (6.077 mmol) of light-sensitive sodium metaperiodate (0.5 equiv. per anhydroglucose units) was added. The pH of mixture was adjusted to 3.0 with hydrochloric acid solution (0.1 M). To prevent light degradation, the mixture containing periodate was meticulously covered with aluminum foil. The reaction mixture was gently stirred 500 rpm at 50 °C in the dark for 24 h. To obtain DAC, the reaction was halted by adding 1 equivalent of ethylene glycol and subjected to multiple washes through centrifugation, washing, and redispersion in water. The removal of soluble aldehyde by-products of the resulting DAC was confirmed through negative Tollens Reagent Test of the wash water, as mentioned in the supporting information (Figures S1 and S2) [102 (link),103 (link),104 (link),105 (link)]. The purified DAC samples were stored in water at 5 °C as a stable suspension for further use.