单斜与六方磁黄铁矿处理含Cr(VI)废水过程中pH值变化规律

Characteristics of pH Variation in the Cr(VI)-bearing Wastewater Disposed by Clino-Pyrrhotite and Hexa-Pyrrhotite

与六方磁黄铁矿相比 ,单斜磁黄铁矿Fe缺位较普遍。在初始 pH值分别为 3.4 0～ 9.6 6和3.4 7～ 9.6 6较宽范围内 ,利用单斜磁黄铁矿和六方磁黄铁矿处理含Cr(VI)废水 ,当反应达到充分平衡时 ,废水的 pH值分别变化在 3.6 1～ 4 .4 7和 5.39～ 6 .57范围内。六方磁黄铁矿除Cr(VI)效果明显不及单斜磁黄铁矿 ,但被氧化的六方磁黄铁矿除Cr(VI)效率有所提高。电化学分析表明 ,在酸性介质中处理的反应过程为H+ 的消耗过程 ,而在碱性介质中则为OH 的消耗过程。根据 pH值的这一变化规律 ,可自行调节处理过程中水质的酸性变化 ,能节省传统工艺中需要加碱以中和处理后酸性水的环节 ,具有一定的实际应用价值。

The content of Fe in the structure of clino-pyrrhotite is l ower than that in the structure of hexa-pyrrotite. The experiments have been ma de to measure the pH variation of the Cr (VI) - bearing wastewater after treatment b y clino-pyrrhotite and hexa-pyrrhotite respectively. The initial pH values are 3 .40～9.66 and 3.47～9.66 respectively; while after treatment, the pH values beco me 3.61～4.47 and 5.39～6.57 respectively. The disposal efficiency of Cr(VI) by c lino-pyrrhotite is higher than that by hexa-pyrrhotite. However, the disposal ef ficiency of Cr(VI) increases with the oxidized hexa-pyrrhotite. Electro-chemic al analysis shows that increase of pH values in acidic media and decrea se of pH valus in basic media during redox reaction are beneficial to practical disposal due to consuming H-+ in acidic media and combination of Fe(II) with OH -- in basic media which are also verified by the experimental results.