赤泥制备含钛聚硅酸铝铁及亚甲基蓝溶液的混凝脱色

以拜耳法赤泥为原料、Na Cl为助溶剂,采用酸浸法溶出赤泥中的铁、铝元素,再与硅酸钠、硫酸氧钛反应制备出高效混凝剂含钛聚硅酸铝铁(T-PSAF),并将其用于模拟亚甲基蓝印染废水的脱色。实验结果表明:在硫酸浓度为8 mol/L、液固比(硫酸体积与干赤泥质量之比)为14 m L/g、酸浸温度为80℃、酸浸时间为80 min、Na Cl加入量为0.10 g/g(以干赤泥计)的优化酸浸条件下,铁、铝的浸出率分别为88.25%和73.21%;在n(Fe+Al)∶n(Ti)∶n(Si)=0.3∶0.3∶1、熟化p H为4~5、熟化时间为2 h、混凝剂加入量为25 m L/L的优化混凝条件下,初始亚甲基蓝质量浓度为10 mg/L的废水的脱色率可达87.1%,而当初始亚甲基蓝质量浓度增至150~200 mg/L时废水脱色率可达99%以上。

Preparation of Titanium-Containing Polysilicate Aluminium Ferric Coagulant from Red Mud and Decoloration of Methylene Blue Solution

Using Bayer red mud as raw materials and NaCl as cosolvent,aluminum and iron in the red mud were leached out with acid,and then reacted with Na₂SiO₃ and TiOSO₄ to prepare the efficient coagulant of titanium-containing polysilicate aluminium ferric （T-PSAF）. The coagulant was used for decolourization of the simulated dyeing wastewater containing methylene blue. The experimental results show that：Under the optimum acid leaching conditions of sulfuric acid concentration 8 mol/L,liquid-solid ratio（the ratio of sulfuric acid volume to dry red mud mass） 14 mL/g,acid leaching temperature 80 ℃,acid leaching time 80 min and NaCl dosage 0.10 g/g （for dried red mud）,the leaching rates of Fe and Al are 88.25% and 73.21% respectively;Under the optimum coagulation conditions of n（Fe+Al）∶ n（Ti）∶n（Si）=0.3∶0.3∶1,curing pH 4-5,curing time 2 h and coagulant dosage 25 mL/L,the decolourization rate of the wastewater with 10 mg/L of initial methylene blue mass concentration is 87.1%,while that of the wastewater with 150-200 mg/L of initial methylene blue mass concentration can reach over 99%.