Optimization of a Bleaching Process for the Conversion of Sugar Beet Pulp Alpha-Cellulose with a High Whiteness Index and Purity

Document Type : Research Article

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Faculty of Chemistry and Chemical Engineering, Malek Ashtar University of Technology, P.O. Box 15875-1774 Tehran, I.R. IRAN

Abstract

A large amount of sugar beet pulps are produced annually as waste which causes environmental pollution. However, the composition of sugar beet pulp indicates the possibility of producing several value-added products. In this study, high-quality α-cellulose was extracted from sugar beet pulp. The purity and optical properties of α-cellulose significantly affect its application in various industries, such as the production of napkins or a variety of papers. The bleaching step has a significant effect on the quality of cellulose. So bleaching conditions including the concentration of NaClO (4.5-1 % w/w), temperature (25-60 °C), and time (15-45 minutes) were optimized based on response surface methodology. The results showed good optical properties, low Kappa number, and high cellulose content (yield) could be achieved when the operating parameters were controlled. Severe bleaching conditions such as higher NaClO concentration or longer bleaching time caused cellulose oxidation and reduced efficiency. Optimal bleaching conditions for SBP were determined as 3.28% (w/w) NaClO at 25 °C for 45 minutes. These conditions led to the production of α-cellulose with a 69.38% of whiteness index, a Kappa number of 1.02, and a yield of 23.16%. The structure of the samples was investigated by SEM and FT-IR analysis. Therefore, the pulping and bleaching process has led to value-added products with industrial applications from sugar beet pulp.

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