Study On Synthesis Of Water-Soluble Schiff Base Metal Complexes And Their Catalytic Properties In Bleaching Cotton Fabrics

Since 1950s, H2O2 has been widely used for bleaching fabric in textile dyeing and finishing industry, but the high temperature in the process leads to high energy consumption and fiber damage. Therefore, it is vital to reduce the temperature in bleaching process by catalysts which have high efficiency in catalytic activity. Schiff base complexes have been widely used in catalytic field due to their structure which is similar to the active center of many enzymes with excellent catalytic activity. At present, there are few reports about using Schiff base complexes as catalysts for H2O2 decomposition.In this study, we synthesized a series of water-soluble Schiff base complexes with catalytic properties. Physical and chemical techniques were used to characterize the complexes. On that basis, we studied the catalytic properties of the complexes for H2O2 decomposition and apply them to the steaming process, cold pad-batch process, and steep process of cotton fabric bleaching.In the first part of this study, water-soluble Schiff base complexes were synthesized by complexation between Cu(Ⅱ), Co(Ⅱ), Mn(Ⅱ) and Schiff bases, which were formed by condensation of salicylaldimine-5-sulphonic acid with ethanediamine and o-Phenylenediamine. EA,TGA,IR were used to characterize the Schiff base metal complexes.In the second part of this study, we discussed pH, and temperature affects the decomposition of hydrogen peroxide. In addition, we investigated the catalytic properties of Schiff base complexes for H2O2 decomposition.In the third part of this study, catalytic properties of CuLl and CoL2 in bleaching cotton fabric at lower temperature were investigated through single factor analysis. The optimization process of the steaming pre-treatment process of cotton fabric in which CuLl was catalyst were listed in the followings:JFC 2 g/L, EDTMPS 0.2 g/L,30%H2O2 30 g/L, catalyst CuLl 24μmol/L, pH=9.5, steaming temperature 80℃, and 60 min. The advantage of the process can be proved by the result of whiteness:71.2%, warp breaking strength retention is 96.0%, and the latitudinal breaking strength retention is 98.8%.The optimization process of the steaming pre-treatment process of cotton fabric in which CoL2 was catalyst were listed in the followings:JFC 2 g/L, EDTMPS 0.2 g/L,30%H2O2 30 g/L, catalyst CuL1 24μmol/L, pH=9.5, steaming temperature 80℃, and 60 min. The advantage of the process can be proved by the result of whiteness:74.0%, warp breaking strength retention is 95.5%, and the latitudinal breaking strength retention is 97.7%.In the fourth part of this study, we studied the application of catalyst CuLl in the Cold Pad-Batch pre-treatment process of cotton fabric and the catalytic properties of CoL2 in bleaching cotton fabric at lower temperature. In the Cold Pad-Batch pre-treatment process, we discussed concentration of stabilizer, content of catalyst, and assistant A affect the whiteness of cotton fabric. The optimization conditions were listed in the followings:JFC 2 g/L, XT-A 3 g/L,30%H2O2 30 g/L, amylase 2 g/L, pectase 2 g/L, catalyst CuLl 18μmol/L, assistant A 6 g/L, pH=9, temperature 40℃, and 60 min. The advantage of the process can be proved by the result of whiteness:52.6%, warp breaking strength retention is 94.1%, and the latitudinal breaking strength retention is 92.5%.In the cotton fabric bleaching process, we discussed concentration of stabilizer, content of H2O2, content of catalyst, and temperature affect the whiteness of cotton fabric. The optimization conditions were listed in the followings:JFC 2 g/L, EDTMPS 0.1 g/L,30%H2O2 30 g/L, catalyst CoL2 15μmol/L, pH=9, temperature 80℃, and 45 min. The advantage of the process can be proved by the result of whiteness:60.3%, bursting strength is 536 N.