腐殖酸对La~(3+),Nd~(3+)等重金属离子混合体系吸附的研究

对含有La~(3+),Nd~(3+)的重金属混合体系进行吸附选择性试验,筛选出腐殖酸浓度为1.2 g·L~(-1)时吸附La~(3+),Nd~(3+)的最佳条件(pH=5.4,温度313 K,振荡时间8 h,重金属离子初始浓度0.15 mmol·L~(-1)),得出此条件下吸附优先顺序为:La~(3+)>Pb~(2+)>Cu~(2+)>Nd~(3+)>Cd~(2+)>Zn~(2+)>Co~(2+)>Cr~(3+);HA的吸附总量在室温下拟合二级动力学方程的效果最好;Langmuir方程则能更好地描述HA对重金属离子的等温吸附过程,并且随着温度的升高,HA的最大吸附量逐渐增加;HA对La~(3+),Nd~(3+)等重金属离子的吸附优先顺序受到pH值、温度、振荡时间、重金属离子初始浓度和本身性质的综合影响,且重金属的地球化学性质是主导因素.

Adsorption of La~(3+), Nd~(3+) and Some Heavy Metal Ions by Humic Acid in A Multi-Metal-Ion System

By making an adsorption test in a multi-metal-ion system, the optimum conditions on adsorp-tion of La~(3+), Nd~(3+) by humic acid, the concentration of which was 1.2 g·L~(-1), were selected as follows: pH = 5.4, temperature 313 K, oscillation time 8 h, and heavy metal ions' initial concentration 0. 15 mmol·L~(-1). The result showed that, under those circumstances, the selectivity sequence of HA to heavy metal ions was La~(3+)> Pb~(2+)> Cu~(2+) > Nd~(3+) > Cd~(2+) > Zn~(2+) > Co~(2+) > Cr~(3+). The total adsorption by HA fitted the best with second-order Kinetic equation in room temperature. The process of adsorption by HA in isothermal condi-tions could be well described by the Langmuir isother-mal equation; and the largest adsorption by HA grew up as the temperature increased; the selectivity se-quence of La~(3+), Nd~(3+) and other heavy metal ions was collectively determined by pH, temperature, oscilla-tion time, and the initial concentration and nature of the heavy metal ions. In addition, each heavy metal's geochemical nature was the dominant factor.