热活化过硫酸盐氧化去除木质素降解产物

Oxidation of lignin-degradation products by heat-activated persulfate

针对生物乙醇生产过程中木质素降解产物对乙醇发酵的抑制作用,选取6种典型木质素降解产物(香草醛、紫丁香醛、4-羟基苯甲醛、香草酸、紫丁香酸和4-羟基苯甲酸)为研究对象,采用新型脱毒技术——热活化过硫酸盐高级氧化技术氧化脱除,研究了氧化去除条件及其氧化机理。结果表明,以0.1 g·L^(-1)的香草醛为代表物质,其最优氧化条件为:p H 6.0,温度80℃,过硫酸盐浓度1.5 g·L^(-1)。在此优化条件的基础上,研究其他5种典型木质素降解产物的氧化效果。结果表明热活化过硫酸盐氧化木质素降解产物的效果显著,香草醛、4-羟基苯甲醛、香草酸、4-羟基苯甲酸和紫丁香酸的去除率在1 h内均达到100%,紫丁香醛的去除率在2 h内也达到100%。热活化过硫酸盐氧化机理主要是通过投加自由基捕获剂甲醇和叔丁醇间接判定在反应过程中的主要活性物种,结果表明在反应中起到主要作用的活性物种是硫酸根自由基。因此,热活化过硫酸盐可以很好地氧化去除木质素降解产物。

Aiming at the effect of lignin-degradation products on ethanol fermentation during the bioethanol production process, six kinds of typical lignin-degradation products（vanillin, syringaldehyde, 4-hydroxybenzaldehyde, vanillic acid, syringic acid and 4-hydroxybenzoic acid） were selected to oxidative removal by a new detoxification technology-advanced oxidation process of heat-activated persulfate. The oxidation removal conditions and its oxidation mechanism were also investigated. The results indicated that the optimal oxidation conditions were p H 6.0, 80℃, and the persulfate concentration of 1.5 g·L^（-1） based on 0.1 g·L^（-1） vanillin. On the basis of the optimized conditions, the oxidation effect of other five of typical lignin-degradation products was studied. The results showed that the effects of oxidation removal were obvious. The removal ratio of vanillin, 4-hydroxybenzaldehyde, vanillic acid and syringic acid reached to 100% within 1 h, while that of syringaldehyde reached to 100% within 2 h. The study of oxidative mechanism was to indirectly decide which the main active species was in the reaction process by the addition of radical scavengers of methanol and t-butanol. The results showed that the main active species were sulfate radicals. Therefore, using heat-activated persulfate is a good way for oxidative removal of the lignin-degradation products.