Department of Chemical and Environmental Engineering, University of Arizona, Tucson AZ, 85721, USA.
Water Sci Technol. 2009;60(9):2345-52. doi: 10.2166/wst.2009.675.
This research investigated the effectiveness of electrocoagulation using iron and aluminium electrodes for treating cooling tower blowdown (CTB) waters containing dissolved silica (Si(OH)(4)), Ca(2 + ) and Mg(2 + ). The removal of each target species was measured as a function of the coagulant dose in simulated CTB waters with initial pH values of 5, 7, and 9. Experiments were also performed to investigate the effect of antiscaling compounds and coagulation aids on hardness ion removal. Both iron and aluminum electrodes were effective at removing dissolved silica. For coagulant doses < or =3 mM, silica removal was a linear function of the coagulant dose, with 0.4 to 0.5 moles of silica removed per mole of iron or aluminium. Iron electrodes were only 30% as effective at removing Ca(2 + ) and Mg(2 + ) as compared to silica. There was no measurable removal of hardness ions by aluminium electrodes in the absence of organic additives. Phosphonate based antiscaling compounds were uniformly effective at increasing the removal of Ca(2 + ) and Mg(2 + ) by both iron and aluminium electrodes. Cationic and amphoteric polymers used as coagulation aids were also effective at increasing hardness ion removal.
本研究调查了使用铁和铝电极进行电凝聚处理含有溶解硅 (Si(OH)(4))、Ca(2+) 和 Mg(2+) 的冷却塔排污 (CTB) 水的效果。在初始 pH 值为 5、7 和 9 的模拟 CTB 水中，测量了每种目标物质在不同混凝剂量下的去除率。实验还研究了防垢化合物和混凝助剂对硬度离子去除的影响。铁和铝电极都能有效去除溶解硅。对于 < or =3 mM 的混凝剂量，硅的去除率与混凝剂量呈线性关系，每摩尔铁或铝去除 0.4 至 0.5 摩尔硅。与硅相比，铁电极去除 Ca(2+) 和 Mg(2+) 的效率仅为 30%。在没有有机添加剂的情况下，铝电极对硬度离子没有可测量的去除。基于膦酸盐的防垢化合物均匀地提高了铁和铝电极对 Ca(2+) 和 Mg(2+) 的去除率。用作混凝助剂的阳离子和两性聚合物也能有效提高硬度离子的去除率。
