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针对氧脱木素硫酸盐浆在二氧化氯脱木素作用中pH对氯酸盐形成的影响作了研究。结果发现,pH从1.8上升到2.5时,氯酸盐有轻微增加;进一步升高pH则使氯酸盐生成量减少。这一现象可以用2个机理共同做出解释:一个是次氯酸和亚氯酸盐的相互作用,另一个是二氧化氯分解出氯气的影响。第1个机理说明氯酸盐的形成很大程度上取决于次氯酸的浓度,而次氯酸的浓度随着pH的上升而降低,因此氯酸盐的形成也以相同的趋势变化。第2个机理说明氯气有利于二氧化氯的再生,同时,次氯酸有助于次氯酸盐的形成,因此pH从4左右再降低会减少氯酸盐的形成量。这2个相反的作用导致氯酸盐形成的最佳pH为2.5。
The effect of pH on the formation of chlorate was investigated in the oxygen delignification kraft pulp during the delignification of chlorine dioxide. The results showed that there was a slight increase of chlorate when the pH was increased from 1.8 to 2.5; further elevation of pH led to a decrease of chlorate production. This phenomenon can be explained by two mechanisms: one is the interaction between hypochlorous acid and chlorite, and the other is the effect of chlorine dioxide to decompose chlorine. The first mechanism shows that the formation of chlorate depends strongly on the concentration of hypochlorous acid, and the concentration of hypochlorous acid decreases with increasing pH, so the formation of chlorate also changes in the same way. The second mechanism shows that chlorine facilitates the regeneration of chlorine dioxide. Meanwhile, hypochlorous acid contributes to the formation of hypochlorite. Therefore, lowering the pH from about pH 4 reduces the formation of chlorate. These two opposite effects lead to the optimal pH of the chlorate formation being 2.5.