Optimization of the process parameters for the production of sodium carboxymethyl cellulose

Abstract

The present work deals with the study of the process, parameters such as alkali concentration for steeping, reaction time, maturing time and reaction temperature for the preparation of sodium carboxymethyl cellulose (SCMC) for obtaining the optimum conditions for commercial application. Experiments were carried out both in aqueous and ethanolic media. On the basis of the experiments carried out 'using glass wares, a.stainless steel stirred cylindrical reactor was used to study the process using a cellulose mass of 50 gm in each batch. Alkalization or steeping was carried out at different alkali concentrations and the suitable concentration to obtain stoichiometric amount of consumption of alkali was ,found to be 18%. Temperature in the range 25-30°C and reaction time for 2 hours were found to be optimum for steeping operation. Maturing time after steeping was established at 12-16 hours. The most suitable conditions for carboxymethylation were reaction temperature = 40 to 45~C; reaction time = 8 hours; and maturing time = 18 to 20 hours. Optimization of the use of reactants was obtained by recycling the reactants and alcohol. The use of make-up reactants decreased with the increase of the number of batches in a cycle. i Alcohol recovery was also improved to 87%. Not all SCMCs produced were soluble in water. Degree of Substitution (DS) varied in the range of 0.69-0.99. Viscosities of 1% and 2% solutions were in the ranges of 7.16-262 centipoise and 35.0 - 2110 centipoise respectively. Water solubility, DS values and solution viscosities of the products indicate that the SCMCs obtained were of commercial quality.