Enhancement of cellulose dissolution in water-based solvent via ethanol-hydrochloric acid pretreatment

Cellulose dissolution in water-based solvents is essential for processing of regenerated cellulose products such as fibres, films and particles. Cellulose dissolution in NaOH-urea aqueous solution has emerged as a simple and attractive alternative for processing cellulose solutions. However, this solvent requires energy intensive pretreatments such as milling or refining. In this paper we investigate a one step chemical pretreatment method using ethanol-hydrochloric acid prior to the dissolution of cellulose in NaOH-urea-water. The dissolution mechanism of the pretreated sample was initially examined in diluted cupri-ethylenediamine and 7% NaOH-12% urea-water solvent using optical microscopy methods and field emission scanning electron microscopy. The apparent energy of activation for the viscous flow of ethanol-acid pretreated pulp in NaOH-urea-water was calculated using rheological methods. Our results showed that the dissolution of pretreated pulp was achieved up to 4% cellulose concentration. We suggest that the enhancement of dissolution was due to a combination of degradation of remnant primary fibre wall layer and reduction of degree of polymerization of cellulose.