Optimization For Synthesis Of Stilbene Derivative Type FWA And Its Adsorption Kinetics On Fiber Surfaces

The stilbene derivative liquid type fluorescent whitening agent is one of the most important fluorescent brighteners that widely used for whitening paper, textile, and other materials. Based on previous studies, an optimization for synthesis of stilbene fluorescent brightener was studied, and the size of bioreactor was scaled up to 20L. Adsorption kinetics for this fluorescent whitening agent (FWA) on fiber surfaces was also studied. This mathematical model of adsorption kinetics is important for the optimization of FWA application in papermaking process.The optimized synthetic process conditions are listed as follow:In the first step of experiment: (1) ethyl alcohol is the best dissolvent;(2) the molar ratio of cyanuric chloride to p-Aminobenzene sulfonio acid anhydrous is 1:1, (3) the molar ratio of ethyl alcohol to cyanuric chloride is 17:1; (4) the reaction temperature is 7℃; the pH of the reacting system is 7-8; the reaction time is 90 minutes.In the second step of experiment: (1) the molar ratio of DSD acid to the product of the first step of complete reaction is 0.40:1;(2) the reaction temperature is 60℃;(3) the pH of the reacting system is 8-10; (4) the reaction time is 120 minutes.In the third step of experiment: (1) the ratio of diethanolamine to cyanuric chloride is 1.1:1;(2) the reaction temperature is 95℃;(3) the reaction time is 120 minutes.In pilot-scale experiments, the conversions and properties of the product are similar to the lab-scale process, indicating that this synthesis is consistent.In this study, adsorption kinetics of stilbene derivative fluorescent whitening agent (FWA) on fiber surfaces was studied by a real-time spectroscopic method, and a mathematical model of this adsorption kinetics wastherefore established: ( all symbols in thisequation are noted in the text and annexed table). This model is important for the optimization of FWA application in papermaking process.The stilbene derivative liquid type fluorescent whitening agent meets to the need of the environment-friendly, it can replace the tradictional powder products after purification and would have strong competitive potential in the market.