氧脱木素过程中羟基自由基的控制

氧脱木素的主要问题是提高其脱木素选择性,而氧脱木素过程中产生的含氧自由基是影响其脱木素选择性的主要因素.而本文用改进的Fenton反应Co2 -H2O2体系产生羟基自由基(HO.),用茜素紫3B的氧化来显色测定HO..将Co2 -H2O2体系与深度脱木素竹浆进行反应,并通过添加HO.捕获剂来控制HO.的数量,研究HO.与竹浆中木素和碳水化合物的反应情况.把HO.捕获剂作为助剂用于深度脱木素竹浆氧脱木素过程,研究HO.的量对氧脱木素过程的影响.研究结果表明,HO.能与木素和碳水化合物发生反应,具有脱木素作用,但对碳水化合物的降解也较严重.HO.捕获剂具有清除HO.的作用,在氧脱木素过程中加入HO.捕获剂能减少碳水化合物的降解,提高氧脱木素选择性.

Regulation of hydroxyl radical in the oxygen delignification process

The main challenge in the oxygen delignification process is the improvement of selectivity. The effect of hydroxyl radical (HO · ) on lignin and cellulose should be considered. In the present paper,it was carried out that the HO · was generated by the improved Fenton reaction of Co2+-H2O2 system and determined by UV spectrophotometry,which can discolour alizarin violet 3B. The HO · can be scavenged by the antioxidants such as ascorbic acid,thiourea,benzoic acid, mannitolum,etc. The bamboo kraft pulps were treated by Co2+-H2O2system or Co2+-H2O2system combined with ascorbic acid. The results indicated that HO · could react with both lignin and carbohydrates,and the HO · scavenger could quench HO·to reduce the degradation of carbohydrates so that the delignification selectivity improvement was achieved in the oxygen delignification process.