Study On Photocatalysis Bleaching Of Bagasse Kraft Pulp

In this study, a series of pulp photocatalysis bleaching reactor were designed and made firstly. In those reactor , mercury lamp with a uartz glass cooler, as a ultraviolet light resource, was external of the reactor, photocatalysis bleaching of the bagasse kraft pulp were operated at atmospheric pressure in these reactors. Evaluation on the results of 5 kinds of photosensitizer( Rose Bengal, Methylene Blue , Eosin Y, Acridine Orange , Fluorescein) were performed, the results suggested that Rose Bengal and Fluorescein were the best. Mechanism of delignification and carbohydrate degradation during the process of photocatalysis bleaching were studied by IR. The optical techniques of EO and RB preparation were studied by the orthogonality experiment. Then, Regulation of HO- consumption and HO yield during the process of photocatalysis bleaching were studied by UV/VIS. Result as follows:1. The results of the orthogonality experiment suggested that the optimal catalyst for EO and RB are same: dosage of photosentizie to 0.5%, dosage of NaOH to 3%, consistency of pulp, photocatalysis time 7h.2. The regulations of HO- consumption and HO. yield were gained nuder vacancy test: when addicting RB, the velocities of HO- consumption and HO. yield were very high at the first of 15 min. A little of HO- were degradated, but HO. were not found in the photocatalysis bleaching when no RB.3. The regulations of HO" consumption and HO. yield were gained under pulp test by contrast analysis: when addicting RB, the velocities of HO" degradation and HO. yield were higher than no RB. And the velocities of HO" degradation and HO. yield were very increased severely when the dosage of NaOH from 3% to 4%at addicting RB. At the same time, the pulp of KMnO4 value and viscosity were degrated at those condition. But the velocities of HO" consumption and HO. yield were down when the dosage of NaOH from 4% to 5%. So, the field of HO can be controled by controling the dosage of NaOH.4. In conclusion, the effect of DMNA clearing HO was very evident. Few delignification and carbohydrate were degrated after HO was cleared. But the aim of pulp — bleaching is to clear or chang the charater of lignin and protect carbohydrate. The field of HO was very suit when addicting RB and no RB separately : the dosage of NaOH to 3% and 4% .