白陶瓷土对多元重金属体系吸附特性研究
Adsorption behaviors of multi-element heavy metal on white pottery clay
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摘要: 主要研究了白陶瓷土对一元(Pb,Cd,Cu)、二元(Pb-Cd,Pb-Cu,Cu-Cd)、三元(Pb-Cd-Cu)体系下金属离子的吸附特性。在一元体系下,分析了白陶瓷土对不同金属的动力学与等温平衡吸附特性,试验结果表明,白陶瓷土对3种金属离子的吸附为快速反应,3 h即可达到平衡吸附,伪二级动力学模型计算结果与试验结果吻合较好,Langmuir模型可较好地预测白陶瓷土对3种金属的等温吸附过程。最大吸附量由大到小的顺序为Pb>>Cu>Cd。在Pb-Cd,Pb-Cu二元体系下,Cu可显著抑制白陶瓷土对Pb的吸附,且吸附量随Cu增加而下降,Cd的影响相对较小;Cu-Cd二元体系下,当Cu浓度高于某一值时,Cd的吸附受到明显抑制,且不随Cu浓度变化而变化。在三元体系下,受离子间竞争吸附叠加效应影响,3种金属的吸附量均显著下降,Pb的吸附量随Cu与Cd浓度增加而下降,而Cu与Cd的吸附量受Pb浓度变化影响较小。Abstract: Batch experiments are conducted to study the adsorption process on white pottery clay for single (Pb,Cd,Cu), binary (Pb-Cd,Pb-Cu,Cu-Cd) and ternary (Pb-Cd-Cu) solutions. In the single system, the kinetics and isothermal balance adsorption characteristics of different metal ions are analyzed. The results show that each of the adsorption process is fast and can reach balance in three hours. The kinetics adsorptions of Pb, Cu and Cd on white pottery clay are well described by the pseudo-second order model. The Langmuir isotherm models can predict the isothermal adsorption process of three metal ions well on white pottery clay. The order of the maximum adsorption capacity of ions is lead >> copper > cadmium. In the binary system of Pb-Cu and Pb-Cd, Cu can significantly inhibit the adsorption of Pb on white pottery clay, and the adsorption capacity decreases with the increase of the initial concentration of Cu. The effect of Cd is relatively small. For the binary metal solution Cu-Cd , the adsorption of Cd is inhibited when the concentration of Cu is higher than a certain value, and no change occurs over the certain value. In the ternary system, because of the superposition effect of competitive adsorption between ions, three kinds of metal adsorptions decline significantly. The adsorption quantity of Pb decreases with the increase of concentration of Cu and Cd, and the change of Pb concentration has less effect on the adsorption amount of Cu and Cd.