Hüseyin Aksel Eren

The evaluation of ozonation as an environmentally friendly alternative for cotton preparation

Ozone is a strongly oxidative gas that is generally used in medical sterilization and decolorization of the effluent of textile spent dyebaths. Recent studies have reported the use of ozone to bleach textile fabrics. In this study, ozone was utilized in cotton preparation for greige, desized and scoured 100% cotton fabrics. Hydrogen peroxide bleaching was performed as the control treatment. The degree of whiteness of cotton increased after prolonged ozonation times. The scoured samples reached the whiteness level of the control (hydrogen peroxide bleached) samples. The whiteness of the hydrogen peroxide bleached, 60-min ozonated and 90-min ozonated samples all had a Stensby degree of whiteness of 81 for the scoured fabric samples. The strength loss after prolonged ozonation times was negligible. Ozonation increased the starch-size removal of the greige cotton samples and the water absorbency of the greige and desized cotton samples.

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.

The effects of ozone treatment on polylactic acid (PLA) fibres

A set of knitted poly(lactic acid) (PLA) fabrics was ozonated at room temperature for periods ranging from one to 60 minutes in order to identify any accompanying effects on physical properties (specifically whiteness, water-absorbency, flexural rigidity and burst strength), fiber surface integrity or internal microstructure. A significant (ca. 6% after 10 minutes of treatment) initial increase in whiteness was observed, with longer treatment times producing little further change. The fabric’s absorbency and flexibility both increased, the time of wetting having fallen by ca. 20% and the flexural rigidity by ca. 16%, respectively, after 10 minutes of treatment. Fabric strength remained virtually unaffected for short times (up to 10 minutes) of ozonation, although longer treatments caused a measurable drop (ca. 10% after 60 minutes). SEM imaging showed virtually no evidence for surface damage, even after 60 minutes of treatment, whereas peroxide treatment caused massive pitting of the fiber surface. Raman spectroscopy of the ozonated PLA fabrics indicated that the treatment had not affected the internal microstructure of the fibers. Our conclusion is that brief (no more than 10 minutes) room-temperature ozonation is potentially an effective, safe and low-energy alternative to conventional higher temperature peroxide treatment.

The Effects of Ozone Treatment on Soybean Fibers

A set of knitted fabrics comprising soybean fibers was ozonated at room temperature for periods ranging from 2.5 to 300 minutes to identify any accompanying effects on either physical properties (specifically whiteness and burst-strength), fiber surface integrity or microstructure. A hydrogen peroxide treatment was applied to some of the fabric in order to provide a comparison. Ozonation was found to produce a promising increase in whiteness which, after the maximum exposure time, was significantly higher than was achieved using hydrogen peroxide.

Substitution of Reduction Clearing Step by Ozone Treatment at Disperse Dyeing of Polyester

The effectiveness of ozone treatment for the afterclearing of disperse dyed poly (ethylene terephthalate) (PET) fibers has been examined. Two types of disperse dyed PET samples were selected among commercial mass production range of Akbaslar textile mill. The reduction clearing procedure applied during mass production was taken as the reference reduction clearing treatment; these reference samples were taken after dyeing and reduction clearing processes at the mill. Samples of disperse dyed PET were also taken before reduction clearing in order apply ozone treatment in the laboratory as the tested afterclearing method. Color and wash-fastness properties of the reduction cleared and ozone treated fabric samples were compared and reported. Results indicated acceptable color and wash-fastness results comparable to those of reduction cleared samples for ozone treated samples. The success of ozone treatment for the black dyed PET sample at 7.0% depth of shade was especially outstanding. Ozone treatment was applied in cold water without addition of any chemicals for very short treatment times when compared to conventional reduction clearing. Ozone treatment created substantial energy and chemical savings as well as lower environmental impact.