Study On Application Of Chlorine Dioxide In Cotton Fabric Pretreatment

At present, scouring and bleaching processes with high temperature and strong alkalinity are always use in the traditional cotton fabric pretreatment processing. However, these processes not only consume large amounts of water and energy, but also cause serious environmental pollution for a large amount of effluent with strong basicity. Consequently, it is imperative to develop energy-saving and emission-reduction pretreatment processing technology. In recent years, the successful application of chlorine dioxide in pulp green bleaching provides cotton fabric pretreatment with reference. In this paper, chlorine dioxide were used to pretreat cotton fabric, and the bleaching effect of chlorine dioxide to removing cottonseed coat, coloring matters and other natural commensal were detailed studied. We looking forward to get the best process of cotton fabric chlorine dioxide pretreatment.First, aiming at of Klason method which is time-costing and of low accuracy&reproducibility, we put forward an method which utilize the UV absorption of lignin acetylation derivatives to determine cottonseed coat lignin content in this paper, and the lignin acetylation reaction conditions were optimized. The results showed that the lignin content of cottonseed coat measured by acetyl bromide procedure is19.59%. Compared to Klason method, the acetyl bromide procedure is not only simple and rapid, but also has an advantage in accuracy and reproducibility.Secondly, the oxidative ability of chlorine dioxide solution has been investigated by measuring its redox potential under different conditions, we found that the oxidative ability of chlorine dioxide can maintain a high level under following circumstances:pH below6, ClO2concentration above8g/L, temperature between60～70℃. The results from which cotton seed coat were degraded with chlorine dioxide solution showed that, under suitable conditions, the weight loss rate of cottonseed coat reach to20%, and make the cotton seed coat effective decolorization. After treatment with chlorine dioxide, cottonseed coat were analyzed by SEM. We found that the complex layered structure of cottonseed coat is destroyed, surface layer falls off, the inlayer structure becomes loose, the cellulose matrix and ribbon hemicelluloses exposed. The IR spectrum of cottonseed coat revealed that the benzene of lignin is oxidized to ring opening to substance with carbonyl groups. In addition, the increase of cottonseed coat xylose content also indicted that cottonseed coat were degraded effectively.At last, the process conditions of cotton fabric pretreatment with chlorine dioxide solution were studied by measuring whiteness, cottonseed coat removal rate, water absorbency, weight loss rate and strength drop rate, and the relationship between treatment conditions and treatment effect were also investigated. The results showed that cotton fabric pretreatment with chlorine dioxide solution was achieved under following conditions:ClO2concentration8g/L, pH=4-5, temperature80℃, time30min. On that basis, the cotton fabric whiteness, cottonseed coat removal rate can reach to78%and100%, water absorbency1s, keep weight loss rate and strength drop rate under3%. Cotton fabric chlorine dioxide pretreatment is not only better than traditional pretreatment on comprehensive treatment effect, but also consumes less quantity of chemicals, low temperature and less time. In general, Cotton fabric chlorine dioxide pretreatment is a effectively pretreatment method.