膨润土对废水中Ni2+的吸附特性研究

为考察膨润土作为吸附剂对含Ni²⁺废水的处理效果，配制不同Ni²⁺初始浓度的溶液作为模拟废水，以山东莱阳鑫达矿业有限公司的天然钙基膨润土为吸附剂进行吸附试验。结果表明：随着Ni²⁺初始浓度的增加，膨润土对Ni²⁺的吸附率逐渐降低；膨润土对Ni²⁺的吸附率随固液比的增加而提高，但增加固液比降低了单位吸附剂的利用率，还提高了后续处理的难度；振荡速度对于膨润土吸附效果影响不大，可以忽略；随着pH值的提高，膨润土对Ni²⁺的去除率逐渐提高；Ni2+的初始浓度为100 mg/L、固液比为12.5 g/L、无振荡，自然pH时，Ni²⁺去除率可达95%以上。为考察溶液pH对膨润土吸附Ni²⁺的影响，考察了不同pH条件下膨润土对Ni²⁺的饱和吸附量，并对其机理进行了分析，结果表明：当溶液pH<7时，H+会与Ni²⁺发生竞争吸附从而降低Ni²⁺吸附率；pH值的提高有利于Ni²⁺的去除，但pH>7.5后Ni²⁺的水解成为主要去除机制；不同pH下，Ni²⁺的不同存在形态也对吸附率产生了影响。试验结果对膨润土作为吸附材料的工业化应用具有指导意义。

Study on Adsorption of Ni( II) in Aqueous Solution with Bentonite

To examine the adsorption of Ni2+ in aqueous solution using bentonite as adsorbent，a series of experiments were conducted with different concentration of Ni²⁺ prepared as simulated wastewater and natural calcium bentonite from Xinda Mining Company in Laiyang County，Shandong Province as adsorbent.Results show that the adsorption decreases with increasing of initial Ni²⁺ concentration but increases with ratio increasing of solid to liquid.Moreover，increasing of ratio of solid to liquid will reduce the unit utilization of adsorbent and increases the difficulty of subsequent processing.Oscillation speed has less impact on the adsorption and it can be ignored.The Ni²⁺ adsorption rate increases with pH increasing.The adsorption rate of Ni²⁺ is nearly above 95% with conditions of the initial concentration of 100 mg/L and the ratio of solid to liquid of 12.5 g/L.The saturated adsorption amount of bentonite for Ni²⁺ is examined under different pH and the influencing mechanism of pH is also analyzed in order to study the effect of pH on the adsorption with bentonite.The adsorption of Ni2+ decreases when pH<7 due to the competitive adsorption of H+ and Ni²⁺ with bentonite.The increase of pH is benefit for the adsorption，but the hydrolysis becomes the dominant removal mechanisms when pH>7.5.Furthermore，the existing form of Ni²⁺ under different pH also influences the adsorption mechanism.The results have great significance for bentonite used as adsorbent material in industrial application.