Preparation Of AOBS And The Study Of Application And Mechanism In Chlorine-Free Bleaching Pulp

Hydrogen peroxide is an important chlorine free bleaching agent, which is widely used in the bleaching of pulp. The key to bleach pulp by hydrogen peroxide is how to improve the efficiency of bleaching. In this thesis, we studied the activation of acyloxybenezenesulfonate(AOBS) to H2O2 bleaching process of kraft eucalyptus pulp, we synthesized sodium iso-nonanoyloxybenzenesulfonate(INOBS) in laboratory, INOBS is one of AOBS . First we studied its activation in H2O2 bleaching process, then we discussed its bleaching mechanism through analyzing the IR spectra of residual lignin. Second we studied the intensification of microwave radiation in H2O2 bleaching process and studied the activated H2O2 bleaching process of Pw,Pinobs and PwI. Third we discussed their function in TCF bleaching pulp. The conclusions drown from experimental data were followed as:1. Sodium iso-nonanoyloxybenzenesulfonate was synthesized using 4-phenolsuflonate sodium and iso-nonanoyl chloride in the presence of xylene as solvent and tetrabutyl ammonium as phase transfer catalyst, which yield and content exceed 85%. The structure of iso-nonanoyloxybenzenesulfonate was characterized by FT-IR spectra analysis, which showed the product was INOBS. The suitable synthesis conditions are: molar ratio of 4-phenolsuflonate to iso-nonanoyl chloride is 2, reaction temperature 140℃, time 6h, catalyst 0.5%.2. INOBS is an effective activator in H2O2 bleaching. The bleached pulp has a higher brightness at a lower bleaching temperature and shorter reaction time compared with the conventional H2O2 bleaching process when it is added in H2O2 bleaching of eucalyptus pulp. The optimal conditions in this activated H2O2 bleaching pulp are as follows: INOBS : H2O2(mol ratio)=0.75, 3% H2O2,reaction time 50 minutes, temperature 50℃, pulp dense 10%, 3% Na2Si04, 0.05%MgSO4.3. Microwave radiation can improve mass transfer rate of system. It is a effect method that reinforce H2O2 bleaching process by utilizing microwave radiation. The optimal conditions in microwave radiation reinforces H2O2 bleaching pulp as follow: microwave power is 900W, pulp dense 10%, 3% H2O2, 3% Na2SiO4,0.05%MgSO4.reaction time 2.5min. In this condition, pulp can achieve better bleaching effect.4. Microwave radiation reinforces H2O2 bleaching can obtain better bleaching effect when add INOBS activator. When the INOBS : H2O2(mol ratio)=0.75, effect of Pulp were better than Pw and Pinobs pulp.5. By INOBS activated H2O2 bleaching, intensified oxygen bleaching can improve the oxygen bleaching capability. It can upgrade the pulp brightness, but lower than using H2O2 to intensify oxygen bleaching alone.6. TCF bleaching combination can be consist of Pinobs,Pw,PwI,Q,Op and Eop. Pulp brightness of QOpPinobs exceed 80%ISO thereinto. Pulp brightness under 80%ISO , which the combination constituted Pw or PwI plus QOp bleaching pulp. Pulp brightness of QOpPwi was very closed 80%ISO. After plusing Eop bleaching pulp, the pulp brightness of QOpEop Pw can pass muster too.7. IR spectra analysis of the different residual lignin shows: using H2O2 alone in pulp bleaching cannot destroy the benzene and the hydroxybenzene, when using activated H2O2 by INOBS bleaching pulp, it can destroy the hydroxybenzene mostly in residual lignin and it can destroy the configuration of benzene through ring-opening reaction because of its power oxidation.