改性粉煤灰吸附处理含重金属离子废水的研究

Adsorption of Wastewater Containing Heavy Metal Ions by Modified Fly Ash

以热电厂产生的粉煤灰为主要原料 ,通过加入一定量的硫铁矿烧渣和适量的固体Na Cl,在 90℃下用硫酸废液搅拌浸取 2 .5h ,再在 30 0℃下焙制 ,得到一种吸附性能优良的吸附剂———改性粉煤灰。在静态条件下 ,研究了改性粉煤灰对重金属离子的吸附性能 ,着重探讨了改性粉煤灰去除工业电镀废水中重金属离子Cr6 + ,Pb2 + ,Cu2 + ,Cd2 + 的适宜条件。结果表明 ,pH值是影响改性粉煤灰对重金属离子吸附的重要因素 ,各金属离子都有其适宜的 pH值范围。在室温、pH =8.0时 ,各重金属离子含量小于 5 0mg/L的含Cr(Ⅵ )电镀废水经改性粉煤灰吸附、沉淀处理后 ,各重金属离子的去除率达97.5 %以上 。

A modified fly ash absorbent with excellent adsorbability was prepared using the fly ash from a thermal power plant as the major raw materials. Thus the fly ash was mixed with a given amount of pyrite cinder and NaCl, stirred and immersed with waste sulfuric acid at 90 ℃ for 2.5 h, and dried at 300 ℃, to allow the generation of the target modified fly ash. The adsorption capability of the modified fly ash to various heavy metal ions was examined under static state condition, with an emphasis being placed on determining the suitable conditions for the removal of the heavy metal ions such as Cr^(6+), Pb^(2+), Cu^(2+), and Cd^(2+) in industrial electroplating wastewater by the modified fly ash. The results showed that the adsorption capability of the modified fly ash to heavy metal ions was greatly dependent on the pH value of the wastewater to be treated, and the suitable pH value ranges varied for different metal ions. After absorbed by the modified fly ash at room temperature and pH=8.0, the heavy metal ions in the Cr(VI) containing electroplating wastewater with every individual heavy metal ion content below 50 mg/L was removed at a rate over 97.5%, and the treated wastewater passed the corresponding national discharge standard.