One-Stage Ecological and Economical Pretreatment of Linen Fabrics

摘要

A sodium chlorite bath for scouring and bleaching of linen fabric by a one-step process is activated by glyoxal as an organic-reducing compound having two aldehyde functional groups. Such activator has been found to be effective in bringing about the progressive decomposition of sodium chlorite. The treatment was achieved under a variety of conditions, and the bleaching effect of sodium chlorite/glyoxal system was appraised by monitoring the treated samples for the degree of whiteness (WI), loss in fabric weight (LW), wettability (W), carbonyl (CO) content, carboxyl (COOH) content, percentage of sodium chlorite decomposed, and tensile strength (TS). The best conditions for concurrent desizing, scouring, and bleaching of linen fabric with excellent whiteness index and acceptable tenacity were found to be 60℃ and at initial pH of 10.35, with aqueous solution containing 5g/L NaClO_2, glyoxal 6 mmol/L, and 2g/L wetting agent for 120 min using the material-to-liquor ratio (M/L) 1:30. Tentative mechanisms were also reported to account for the bleaching action of NaClO_2/glyoxal system.