镉和磷酸根离子在铝柱撑膨润土上的协同吸附  

Collaborative sorption of cadmium and phosphate ions to hydroxyaluminum pillared bentonites

作　　者：李芳郴[1] 罗岳平 陈镇[1] 戴友芝[3] 葛飞[3] 许银[3] 

机构地区：[1]湖南工程学院化学化工系,湘潭411104 [2]湖南环境监测中心站,长沙410019 [3]湘潭大学化工学院,湘潭411105

出　　处：《环境工程学报》2015年第11期5482-5486,共5页Chinese Journal of Environmental Engineering

摘　　要：羟基金属柱撑粘土矿物表面带有大量强反应活性的羟基金属基团,因而对重金属阳离子和和含氧酸根阴离子都具有很好的吸附能力,相关研究特征也有大量研究报道。但实际环境中重金属阳离子和和含氧酸根阴离子往往共存,而它们在柱撑粘土上同时吸附的特征则鲜有研究报道。以铝柱撑膨润土(Al-Bent)为柱撑粘土代表,研究了重金属阳离子Cd2+和含氧酸根阴离子磷酸根(H2PO-4)共存条件下2种污染物在Al-Bent上的吸附特征。研究结果显示,Cd2+和H2PO-4在Al-Bent上具有协同吸附效应,即共存离子可以促进Al-Bent对另一污染物的吸附性能。吸附过程的p H变化特征表明,Cd2+主要通过与铝羟基上的H交换被吸附,H2PO-4则与铝羟基上的羟基交换被吸附;而两者共同吸附时,则可形成AlPO4-Cd三元络合物。XPS研究结果进一步证实了在Al-Bent上生成了三元络合物。因此,羟基金属柱撑粘土作为多功能吸附剂可用于含重金属阳离子和含氧酸根阴离子的复杂废水的处理。Hydroxymetal pillared clay minerals（ Hy-clay） contain reactive surface hydroxyl groups,and they have a high adsorption affinity for both heavy metal cations and oxyanions. Until now,the adsorptive characteristics of the two types of contaminants individually on the Hy-clay have been extensively studied. However,the co-adsorptive characteristics of these two contaminants on Hy-clay were rarely reported,despite the fact that they generally co-exist in the environment. In this work,hydroxyaluminum pillared bentonite（ Al-Bent） was selected as a representative of Hy-clay,and its co-sorptive characteristics toward typical heavy metal cation（ i. e.,Cd2 ＋） and oxyanion（ i. e.,phosphate,H2PO-4） were studied. The results showed that Cd2 ＋and H2PO-4could be simultaneously and synergistically sorbed to Al-Bent. Sorption of Cd2 ＋could cause the decrease of solution p H,indicating an exchange of Cd2 ＋with H＋from the hydroxyaluminum. On the other hand,sorption of H2PO-4could cause the increase of solution p H,indicating an exchange of H2PO-4with OH-from the hydroxyaluminum.When both contaminants were sorbed,change of solution p H become less evident,indicating the formation of AlPO4-Cd ternary complexes. X-ray photoelectron spectroscopy further proved the formation of Al-PO4-Cd ternary complexes. As such,Hy-clay as multifunctional adsorbent can be used for the simultaneous removal of heavy metal cations and oxyanions from wastewater.

关 键 词：柱撑膨润土 镉(CD) 磷酸根 协同吸附 

分 类 号：X522[环境科学与工程—环境工程]