Synthesis of Carboxymethyl Cellulose from Sugarcane Bagasse

Sugar cane bagasse is a potential cellulose source, though usually used as a fuel source for the boiler. This work reports concisely on a method to utilize sugar cane bagasse for preparing sodium carboxymethylcellulose (CMC) and its characteristics. The desirable characteristics that are imparted on the cellulose were the solubility, viscosity and others which are responsible for many applications. Furthermore, in this work the carboxymethylation reaction was optimized against the reaction temperature, reaction time, monochloroacetate concentration and sodium hydroxide concentration. The sugar cane bagasse is obtained shortly after the juice is extracted in the roller mill. Sodium hydroxide, chloroacetic acid and isopropanol were used for the carboxymethylation process. Firstly, the sugarcane bagasse was dried, ground to pass 1mm screen. Then the cellulose was extracted using 4N NaOH at 100oC for 1 hour. Finally, cellulose was converted to carboxymethyl cellulose (CMC) by basification and etherification processes using sodium monochloroacetate and sodium hydroxide. Two reactions were taken place simultaneously during carboxymethylation that were the primary reaction which produces pure carboxymethyl cellulose and side reaction that produce undesired sodium glycolate. The degree of substitution and viscosity were determined and then analyzed with respect to the reaction conditions using design expert statistical software. From the analysis the maximum degree of substitution was 1.92, and the maximum viscosity 25.4 cp. But after optimization of reaction conditions had been carried out, the optimized degree of substitution was 1.79 and viscosity 14.63cp. These were obtained at a reaction temperature of 30oC, reaction time of 2.95 hours, NaOH concentration of 25% w/v and chloroacetic acid concentration of 0.5 w/w. It is concluded that the sugarcane bagasse is a good source of cellulose that can be modified by etherification reaction to carboxymethylcellulose with a medium degree of substitution of about 1.79. Keywords: Degree of substitution, cellulose, carboxymethyl cellulose, sugar cane bagasse.