Study On Synthesis Of Saltren Metal Complexes And Their Application In H₂O₂Bleaching Cotton Fabric At Low Temperature

Since1950s, H2O2has 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’s significant to reduce the temperature in bleaching process by using catalysts that have high efficiency in catalytic activity. The structures of Saltren complexes are similar to the active center of many enzymes with excellent catalytic activity. They have been widely used in laundry cleaning, hard surface cleaning and pulp bleaching field. At present, there are few reports about using Saltren complexes as catalysts for H2O2decomposition in dyeing and finishing industry.In the first part of this study, Saltren ligand were synthesized by condensation of salicylaldehyde and sodium salicylaldehyde-5-sulfonate with Tris(2-aminoethyl)amine. Then, Saltren complexes were prepared by a reaction of ligand with metal Mn(Ⅱ), Cu(Ⅱ), Co(Ⅱ), Fe(Ⅱ), Fe(Ⅲ) salts. The chemical structures of the complexes were characterized and analyzed by EA, IR,’H NMR.In the second part of this study, pH and temperature effects on the decomposition of H2O2have been discussed. In addition, catalytic properties of different kinds of Saltren complexes have been investigated.The application of the complexes in low temperature bleaching of cotton knitted fabric using exhaustion method was investigated in the third part of this study. Firstly, the complex MnL1was screened out through experiments due to the highest catalytic activity in low temperature. Secondly, low temperature bleaching of scoured cotton knitted fabric with MnL1and effect of key bleaching variables such as temperature, concentrations of MnL1, hydrogen peroxide and stabilizer on the bleaching performance were investigated in detail. The optimal bleaching process was obtained through one factor and response surface experiments and listed as follow:30%H2O28g/L, scouring agent ZJ-CH601g/L, stabilizer PBTCA0.5g/L, complex10μmol/L, pH=10.5, liquor to goods ratio of20:1, bleaching at temperature70℃for60min. The fabric bleached with the optimal process achieved the whiteness index60.21%and the bursting strength retention88.13%. The whiteness index and wettability of the bleached fabric are comparable with those bleached with the conventional high temperature technique.