镁铁水滑石的制备及其对高纯石英砂酸洗含氟废水的吸附性能研究

Study on preparation of Mg-Fe hydrotalcite and its adsorption property of fluorine-containing waste water from pickling of high purity arenaceous quartz

高纯石英砂是半导体、光纤等高新技术行业的重要原料之一,其生产过程中的石英矿酸洗工序会产生大量含氟废水,直接排放会污染地下水源。以硝酸铁、硝酸镁为金属离子来源、氢氧化钠和碳酸钠为混合沉淀剂,采用共沉淀法成功制备了镁铁层状双金属氢氧化物(Mg-Fe LDHs)吸附材料。吸附试验结果表明,在最佳吸附条件下,Mg-Fe LDHs在400℃及N_(2)保护下煅烧2 h获得的样品Mg-Fe LDO400对F-的吸附容量达到9.36 mg/g。模拟的石英矿酸洗高氟废水溶液的F-质量浓度为5 mg/L,F-去除率达到77%,吸附平衡时F-质量浓度为1.15 mg/L,低于世界卫生组织制定的地下水准则值,该工艺可以实现石英矿酸洗高氟废水的高效除氟。

High purity arenaceous quartz is one of the important raw materials applied in semiconductor,optical fiber and other high-tech industries.However a large amount of fluorine-containing wastewater is generated from the pickling of quartz ores for the producing high purity arenaceous quartz,during which the underground water may be contaminated due to the emission.With ferric nitrate and magnesium nitrate as source of metal ions,sodium hydroxide and sodium carbonate as the mixed precipitant,Mg-Fe layered double hydroxides(Mg-Fe LDHs)for adsorption was prepared by use of coprecipitation process.The adsorption tests show that under the optimal adsorption conditions,the fluorine adsorption capacity of the sample Mg-Fe LDO400 after being calcinated at temperature of 400℃in pre-sence of nitrogen for 2 hours was as high as 9.36 mg/g.The fluorine content in the high-fluorine wastewater from the pickling of man-made quartz ore was 5 mg/L.Upon achieving fluorine rejection of 77%,and the equilibrium concentration of fluorine dropped to 1.15 mg/L which was lower than the threshold concentration stated by World Health Organization,so that efficient removal of fluorine from high fluorine-containing wastewater from pickling of quartz ores can be operated significantly.