Study On The Oxidation Degradation Of Triphenylmethane Dyes And Their Application

Chapter 1:A summary about the classification of the triphenylmethane dyes and their applications are introduced, the recent progress about the oxidative degradation method and mechanism of triphenylmethane dyes are reviewed, too. At last the content and significance of research are clarified.Chapter 2:Malachite green, basic fuchsin, brilliant green and crystal violet are taken as model compounds, and the degradation conditions of four model dyes are studied with the oxidation of sodium percarbonate. The optimal conditions such as pH, temperature, bleaching time and the dosage of oxidant for bleaching process were investigated based on degradation rate. The results showed that the optimum pH is 11, and room temperature is selected as the optimum temperature. However, the degradation time and the dosage of oxidant are varies due to the different structure of dyes. When adding 2mL 50mg/L sodium percarbonate solution to four kinds of 10mg/L dyes solution, respectively, and the degradation time is 20min, their degradation rates are high, The order of degradation rate is:malachite green>brilliant green> basic fuchsin> crystal violet. It is showed that sodium percarbonate is suitable for the degradation of triphenylmethane dyes.Chapter 3:The degradation mechanism of four model compounds are studied by the changes of their UV-visible spectra after adding sodium percarbonate solution, respectively. During the whole process of oxidative degradation, the maximum absorption peak gradually disappeared and whole conjugated chromosphere structure of dyes has been destroyed. At the same time, there is the N-dealkylation reaction which can be characterized by the blue-shift at the maximum absorption peak. Since the intermediates generated during degradation, the original absorption peak disappeared and new absorption peak generated. It inferred that the possible degradation mechanism of four triphenylmethane dyes included two dominant reaction courses:(1)HOO- attack on central carbon reaction;(2)N-dealkylation reaction. In addition, there may involve some further reaction like removal of benzene reactions and open-ring reactions.Chapter 4:The silica-coated triphenylmethane dyes microspheres were synthesized by Stober reaction, and the microspheres are characterized by UV-visible spectroscopy, infrared spectroscopy, and transmission electron microscopy. IR spectra verified that the silica has been coated on the surface of the dyes. TEM showed that the average diameter of microspheres is about 250nm. The weather resistance of microspheres was improved than bare dye molecules. The acid and alkali resistance investigation by GB5211.6-85 method showed that the as-prepared microspheres has good acid and alkali resistance ability. The water-based ink was synthesized by water-soluble acrylic ester emulsion, microspheres and some additives. The ink has a good bleaching performance in the sodium percarbonate solution, and can completely fade within 40 min.