粉煤灰制备聚硅酸复合聚合硫酸铁及性能研究

Utilizing Fly Ash to Prepare Polysilicon Acid and Compounded PFS and the Study of Its Properties

以大连某热电厂的固体废弃物粉煤灰为原料,研究了利用粉煤灰制备聚硅酸复合聚合硫酸铁及其絮凝性能.采用NaOH溶液浸渍粉煤灰,通过考察温度、NaOH浓度和反应时间对硅溶出的影响,确定了硅溶出的最佳反应条件.用NaOH浸渍液制备聚硅酸后再与聚合硫酸铁(PFS)复合得到复合絮凝剂(F-PFS),通过考察铁硅摩尔比和熟化时间对F-PFS的除浊性能的影响,确定了F-PFS的最佳复合条件.在F-PFS的最佳复合条件下,以Na2SiO3为原料制备同样硅浓度的聚硅酸再复合PFS得到聚硅酸复合聚合硫酸铁(N-PFS),作为F-PFS的对照.通过最佳F-PFS与N-PFS和PFS的絮凝率对比评价了最佳F-PFS的絮凝性能.结果表明在120℃下,用4mol·L-1的NaOH浸渍粉煤灰4h后得到硅的最大溶出量0.2079g.g-1.在铁硅摩尔比为1∶0.2,熟化2h的条件下,F-PFS的除浊性能最佳.同时F-PFS的除浊能力与N-PFS相同,但是沉降性和稳定性优于N-PFS和PFS,对实际废水的絮凝能力优于N-PFS和PFS.

Fly ash which is a kind of solid waste of power station in Dalian was prepared as polysilicon acid, and compound polymerized ferric sulphate and its properties was studied. Fly ash was dipped in NaOH solution. The effects of temperature, concentration of NaOH solution and reactive time were examined respectively on the conversion efficiencies of silicon. Then the solution which was rich in silicon was used to compound polymerized ferric sulfate （PFS）and got compounded polymerized ferric sulphate （F-PFS）, and evaluated the effects of slaking time and Fe^3＋/Si molar ratio on conversion efficiencies of silicon. Then used Na2SiO3 to prepare polysilicon acid compounded polymerized ferric sulphate （N-PFS） with the same silicon concentration at the best condition. The best ratio of dissolved silicon 0.207 9 g·g^-1 was attained at the condition of 4 mol·L^-1 NaOH solution, 120 ℃ for 4 h. The coagulant was attained at the condition of Fe^3＋/Si molar ratio of 1 ： 0.2 and slaking time of 2 h. The reducing turbidity by F-PFS is the same as N-PFS, but F-PFS is better than N-PFS and PFS is in the stabilization, sedimentation, and the property of treating with urban sewage.