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STUDY OF THE EFFICIENCY OF BIOSCOURING TREATMENT BY DETERMINATION OF THE RESIDUAL CA2+ FROM FLAX-COTTON FABRICS

Monica Pustianu, Mihaela Dochia, Simona Gavrilas, Daniel Tomescu

Abstract

The efficiency of bioscouring treatment applied on 50 % of flax + 50 % of cotton material by determination of the residual Ca2+ was studied. The treated samples were analyzed using a spectrophotometric method based on the measuring of the colour strength [K/S] of the bioscoured material after dyeing with Ruthenium red and Alizarin. The reflectance (R %) at 540 nm was measured and [K/S] values were calculated [1, 2]. The purpose of bioscouring was the removal of morphological impurities present in the cotton and flax fibers such as: pectins, hemicelluloses, waxes, minerals, organic acids, etc. Pectin is a heteropolysaccharide having as a basic structural unit D-galacturonic acid. These units are linked together by Ca2+ bridges. During the bioscouring process in the presence of the pectinolytic product the pectin is hydrolyzed, releasing the Ca2+.ions. The treatment was done in the presence of ultrasound (45 KHz) with a commercial product named Beisol PRO (a mixture of pectinases) in phosphate buffer solution of 0.1 molar at pH 8 with the addition of 2 g/L EDTA (complexing agent) and 0.5 % Denimcol Wash RGN (washing agent). All the experiments were done after a central, correlation, rotatable, second order compound program with two independent variables: enzyme concentration (1-3 % o.w.f.) and treatment time (15-55 minutes). The liquor to fabric ratio was 20:1 and the temperature of 55 пїЅC. The colour strenght [K/S] of the dyed samples fabrics was calculated from the reflectance value measured with a spectrophotometer Datacolor 500 at the maximum absorption wavelength of 540 nm. Ruthenium red and Alizarin dyes are able to form salts in the presence of Ca2 + which can be identified by a color reaction. As a direct result of these reactions, for the enzymatic treated samples, lower values of the intensity dyeing [K/S] were obtained compared to the control sample because of the elimination of Ca2 + ions from the system. The amount of calcium from the treated samples at different enzyme concentrations and different treatment time was calculated in comparison with the control which was the untreated material considered to have the greatest amount of calcium.

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