轮叶黑藻(Hydrilla verticillata)干粉对重金属吸附特征的研究

研究了不同pH值、反应时间、反应温度以及重金属质量浓度条件下,轮叶黑藻(Hydrilla verticillata)植物干粉对重金属(Cu、Cd、Pb、Zn)的吸附影响,阐述了其对重金属的吸附特征及机理.结果表明,不同pH值、反应时间和反应温度条件下,轮叶黑藻植物干粉对重金属的去除率依次为Pb(Ⅱ)Cd(Ⅱ)Zn(Ⅱ)Cu(Ⅱ),吸附的Langmuir模型中R2变化范围非常大,而Freundlich模型中R2多大于0.9.该吸附过程很好地符合Lagergren二级动力学方程,而一级方程的R2基本小于0.5,表明吸附过程不是简单的单分子层吸附,整个吸附过程中颗粒内扩散机理在起着支配作用.FTIR图谱显示,植物干粉各组分吸附重金属前后的基本峰形没有改变,只有羟基(3 300～3 400 cm-1处强宽吸收峰)、羧基(1 400～1 440 cm-1)、酰胺基(1 620～1 645 cm-1)等吸收峰发生了不同程度的位移.

CHARACTERIZATION OF HEAVY METALS ADSORPTION BY DEHYDRATED POWDER OF HYDRILLA VERTICILLATA

The characteristics and mechanisms of heavy metals (Cu, Cd, Pb, Zn) adsorption by dehydrated powder of Hydrilla verticillata were studied in terms of pH values, reaction times and temperatures, and heavy metal ion concentrations. The results showed that with different pHs, reaction times and temperatures, the removal rates of heavy metal were as follows: Pb(Ⅱ)Cd(Ⅱ)Zn(Ⅱ)Cu(Ⅱ). When Langmuir model of heavy metals adsorption was applied, R2 would demonstrate a huge variation. But in Freundlich model, the R2 values exceeded 0.9 in most cases. It showed that the adsorption process of H. verticillata powders against heavy metals fitted the Lagergren second-order equation whereas the R2 values for first-order equation were less than 0.5. The results indicated that the mechanism of heavy metal adsorption by H. verticillata did not simply work on the mono-molecular layer level. The intra-particulate dispersal is the dominant process. As shown in the FTIR spectra, the peak shape of the powder did not change after adsorption with metal ions. Only absorption peaks of some functional groups shifted, such as hydroxy groups (3330～3400cm-1) , carboxyl groups (1400～1440cm-1), and acidamide groups (1620～1645cm-1) when they participated in the process of absorbing heavy metals.