He En, Lü Changwei, He Jiang, Zhao Boyi, Wang Jinghua, Zhang Ruiqing, Ding Tao
College of Environment and Resources, Inner Mongolia University, Hohhot, 010021, China.
Institute of Environmental Geology, Inner Mongolia University, Hohhot, 010021, China.
Environ Sci Pollut Res Int. 2016 Nov;23(22):22667-22677. doi: 10.1007/s11356-016-7487-2. Epub 2016 Aug 24.
Humic acids (HAs) determine the distribution, toxicity, bioavailability, and ultimate fate of heavy metals in the environment. In this work, ten HA fractions (F1-F10) were used as adsorbent, which were sequentially extracted from natural sediments of Lake Wuliangsuhai, to investigate the binding characteristics of Cu to HA. On the basis of the characterization results, differences were found between the ten extracted HA fractions responding to their elemental compositions and acidic functional groups. The characterization results reveal that the responses of ten extracted HA fractions to their elemental compositions and acidic functional groups were different. The O/C and (O + N)/C ratio of F1-F8 approximately ranged from 0.66 to 0.53 and from 0.72 to 0.61, respectively; the measured results showed that the contents of phenolic groups and carboxyl groups decreased from 4.46 to 2.60 mmol/g and 1.60 to 0.58 mmol/g, respectively. The binding characteristics of Cu to the ten HA fractions were well modeled by the bi-Langmuir model; the binding behavior of Cu to all the ten HA fractions were strongly impacted by pH and ionic strength. The FTIR and SEM-EDX image of HA fractions (pre- and post-adsorption) revealed that carboxyl and phenolic groups were responsible for the Cu sorption on the ten sequentially extracted HA fractions process, which is the same with the analysis of the ligand binding and bi-Langmuir models Accordingly, the adsorption capacity of the former HA fractions on Cu were higher than the latter ones, which may be attributed to the difference of carboxyl and phenolic group contents between the former and latter extracted HA fractions. Additionally, the functional groups with N and S should not be neglected. This work is hopeful to understand the environmental effect of humic substances, environmental geochemical behavior, and bioavailability of heavy metals in lakes.
腐殖酸（HAs）决定了环境中重金属的分布、毒性、生物有效性及最终归宿。在本研究中，从乌梁素海天然沉积物中依次提取得到十个腐殖酸组分（F1 - F10）作为吸附剂，用于研究铜与腐殖酸的结合特性。基于表征结果发现，这十个提取的腐殖酸组分在元素组成和酸性官能团方面存在差异。表征结果表明，十个提取的腐殖酸组分对其元素组成和酸性官能团的响应各不相同。F1 - F8的O/C和（O + N）/C比值分别大致在0.66至0.53以及0.72至0.61范围内；测量结果显示，酚羟基和羧基含量分别从4.46 mmol/g降至2.60 mmol/g以及从1.60 mmol/g降至0.58 mmol/g。铜与这十个腐殖酸组分的结合特性通过双朗缪尔模型得到了很好的拟合；铜与所有十个腐殖酸组分的结合行为受到pH值和离子强度的强烈影响。腐殖酸组分（吸附前后）的傅里叶变换红外光谱（FTIR）和扫描电子显微镜 - 能谱仪（SEM - EDX）图像表明，羧基和酚羟基是铜在十个依次提取的腐殖酸组分上吸附过程的主要作用基团，这与配体结合分析和双朗缪尔模型的结果一致。因此，先前的腐殖酸组分对铜的吸附能力高于后者，这可能归因于前后提取的腐殖酸组分中羧基和酚羟基含量的差异。此外，含氮和硫的官能团也不容忽视。本研究有望有助于理解腐殖物质的环境效应、湖泊中重金属的环境地球化学行为及生物有效性。
