Pervin Anis

Enzymatic One-bath Desizing — Bleaching — Dyeing Process for Cotton Fabrics

The objective of this study was to develop a new process to desize, bleach, and dye starch-sized cotton fabrics in one bath using enzymes. Desizing was performed with an amyloglucosidase/pullanase enzyme (Dextrozyme DX, manufactured by Novozymes) instead of a conventional amylase enzyme in order to hydrolyze starch into single glucose units. Multifect GO 5000L (Genencor) glucose oxidase enzyme was used to yield hydrogen peroxide from the glucose generated during desizing; bleaching was performed by this enzymatically generated hydrogen peroxide. Decomposition of hydrogen peroxide after bleaching was done with Terminox Ultra 10L (Novozymes) catalase enzyme. The fabric was dyed in the same bath with the selected monochlortriazine reactive dyes (DyStar). The amount of glucose generated during desizing was 4000 ± 135 mg/l and it yielded 765 ± 15 mg/l hydrogen peroxide during glucose oxidase enzyme treatment. The whiteness index of the enzymatically bleached fabric was 71.0 ± 1.2 stensby degree. The color yields of the enzymatically treated samples were comparable to the conventionally treated samples. All enzymes used in this study were commercial grades having the advantages of easy storage and supply compared to the pure enzymes used in earlier studies. The advantages of the new one-bath process were: less auxiliary demand; lower environmental impact; and energy and water savings compared to the conventional desizing, scouring, bleaching, and dyeing sequence.

Surface Trimer Removal of Polyester Fibers by Ozone Treatment

The oxidative ozone treatment of poly (ethylene terephthalate) fibers after dyeing was recently proposed as a novel afterclearing method. High fastness properties, energy and time savings, and environmental benefits were reported by the ozone treatment compared to the conventional reduction clearing. This study investigated the efficiency of the ozone treatment afterclearing process on the surface trimer removal of poly(ethylene terephthalate) fibers. Results indicated similar cyclic trimer [(GT)3] removal rates after 1 min ozone treatment when compared to the conventional reduction clearing; the removal rates increased at 3 min ozone treatment time. The migration rate of the cyclic trimers [(GT)3] out of the fibers was also investigated as a function of temperature and a sudden increase was observed after second glass transition temperature of poly (ethylene terephthalate) fibers rather than a linear increase.

Investigation of the effects of environmentally friendly degumming methods on silk dyeing performance

In this paper, firstly the effects of environmentally friendly degumming methods on the morphology and structure of fibers have been investigated. Then the dyeing behaviors of environmentally friendly degummed silk fibers were analyzed. In the dyeing process, acid and reactive dyes were used at various dye concentrations. To analyze dyeing characteristics of these fibers, investigations of washing fastness and measurements of color parameters were carried out. Scanning electron microscopy (SEM) images of degummed silk fibers showed that the high temperature (HT) degumming method was more successful than the other methods, but the results were comparable. Weight loss values were also supported by SEM images. Scanning electron microscopy with energy-dispersive X-ray analysis of degummed fibers showed that particles remaining on the surface were the most likely to indicate sericin residue. Fourier transform infrared spectra of raw and degummed fibers with different methods demonstrated typical absorption bands appointed to the peptide bonds (-CONH-) and no major differences were observed. When band intensity was examined, the most intense bands belong to the HT degumming process. The differential scanning calorimetry curves of conventionally and alternatively degummed silk fibers showed two endotherms at around 100℃ and 320℃ because of water loss and β-sheet fibroin decomposition, respectively. The acid and reactive dyeing of the degummed fibers by environmentally degumming methods gave similar color strength and washing fastness values compared with conventionally degummed fibers.