多元竞争体系下的微界面动力学响应机理研究—以细颗粒泥沙吸附多元重金属离子铅、铜和镉为例

Study on response mechanism of the micro-interface kinetics under multicompetition system:A case study of multiple heavy metal ions such as lead,copper and cadmium adsorption on fine sediment

研究微界面动力学响应机理能更好地了解动力学扩散模式的内在机制.通过竞争吸附实验,采用微界面作用模式识别多元重金属离子铅、铜和镉在泥沙颗粒上的扩散模式,探究多元重金属离子的液相浓度和吸附速率变化规律,剖析多元竞争体系下的微界面动力学响应机理.结果显示,10 min前,多元竞争体系下离子的液相浓度和吸附速率变化较大,为快速吸附阶段,与扩散速率较大的膜扩散过程对应.10 min后,离子的液相浓度波动变化,吸附速率变化呈“N型”、“倒N型”、“W型”和“倒W型”特征,吸附解吸交替进行,不同竞争体系离子的液相浓度和吸附速率变化不同,进入孔隙的时间存在差异,此阶段为膜扩散和颗粒内扩散并存,不同竞争体系的离子的颗粒内扩散时间不一致.60 min后,离子的液相浓度较稳定和吸附速率较小,微界面作用趋于稳定,为扩散速率较小的颗粒内扩散阶段.研究结果可为多元竞争体系的微观界面动力学响应机理提供理论支撑.

To understand the internal mechanism of kinetics diffusion mode well,the response mechanism of the micro-interface kinetics have been studied.Based on the competitive adsorption experiment datas,the diffusion mode of multi-heavy metal ions lead,copper and cadmium on sediment particles was identified by micro-interface action mode in this study.The change patterns for the liquid concentration and adsorption rate of multi-heavy metal ions were determinded,and the kinetics response mechanism of micro-interface under multi-competitive system was analyzed.The results show that before 10 min,the liquid concentration and adsorption rate of the ions change greatly under the multi-competition system,which is a rapid adsorption stage,corresponding to the film diffusion process with a large diffusion rate.After 10 min,the liquid phase concentration of the ions fluctuate,and the change patterns for the adsorption rate are"N-type","Inverted N-type","W-type"and"Inverted W-type".Adsorption and desorption are carried out alternately.The liquid phase concentration of the ions and adsorption rate change differently under different competitive systems,and the time of entering pores is different.The film diffusion and intra-particle diffusion coexist,and the intra-particle diffusion time of the ions under different competitive systems is inconsistent at after 10 min stage.Furthermore,the liquid phase concentration of the ions is stable,the adsorption rate is low,and the micro-interfacial interaction tends to be stable,which is the intra-particle diffusion stage with low diffusion rate at after 60 min stage.