Abstract: Aluminum-containing wastewater was used to synthesize ammonium alum by crystallization. The effects of time, NH4+/Al3+ molar ratio, SO42-/Al3+ molar ratio, temperature and stirring speed on the aluminum alum formation and aluminum ion removal rate were studied. The synthesized and commercial ammonium alum products were characterized, they had almost identical crystal structure, morphology and chemical composition. The optimum conditions of efficient crystallization process were recommended: operation time of 8 h, NH4+/Al3+ of 1.40, SO42-/Al3+ of 2.90, temperature of 5~15℃ and stirring speed of 35~55 r/min. The synthesis reaction kinetics experiments were performed. The results show that Al3+ diffusion in the boundary layer is the rate controlling step in the crystallization process. The relationship between Al3+ concentration (C) and time (t) is expressed by C=(C0-Ci)e-kt+Ci. The effect of stirring speed on the particle size distribution of ammonium alum crystals was investigated. When the stirring speed is lower, ammonium alum average particle size is larger and size distribution wider. With increasing of stirring speed, the particle size and distribution range are decreased.

Key words: ammonium alum, lipoic acid, wastewater containing aluminum, reactive crystallization, kinetics

摘要： 以硫辛酸厂含铝废水中的Al3+为原料，采用结晶法制备铵明矾，研究了时间、NH4+/Al3+摩尔比、SO42-/Al3+摩尔比、温度、搅拌速度对废水中铝去除率和铵明矾产量的影响，对所制铵明矾与商品铵明矾进行比较. 结果表明，两者具有几乎相同的晶体结构、形貌和化学组成，所得产品符合同类工业产品标准. 结晶法用硫辛酸厂含铝废水制备铵明矾的适宜条件为：反应时间8 h，NH4+/Al3+ 1.40，SO42-/Al3+ 2.90，温度5~15℃，搅拌速度35~55 r/min. 宏观反应动力学表明，在晶体生长期，Al3+在边界层扩散传质为反应控制步骤，液相主体Al3+浓度C随时间t的变化关系符合方程C=(C0-Ci)e-kt+Ci. 当搅拌速度较低时，铵明矾晶体平均粒径大，分布宽；搅拌速度增加，晶体平均粒径减小，粒径分布变窄.

关键词: 铵明矾, 硫辛酸, 含铝废水, 反应结晶, 动力学