Humic substances with or without chemical modification can serve as environmentally benign and inexpensive adsorbents of potentially toxic trace elements (PTTEs) in the environment. The present study investigated the absorption of Pb, Zn, Cu and Ni by natural and potassium persulfate (K₂S₂O₈) modified humic acids (HAs) isolated from a lowland peat through batch experiments. The adsorption of the studied PTTEs on the natural HA was satisfactorily described by the Langmuir isotherm model with maximum monolayer adsorption capacities of 318.2, 286.5, 225.0 and 136.8 mmol/kg for Pb, Cu, Zn and Ni, respectively. A thorough characterization of the natural and modified HA using ¹³C nuclear magnetic resonance spectroscopy demonstrated that the chemical modification of natural HA with K₂S₂O₈ led to an increase in the content of carboxyl groups, and ketone and quinoid fragments in the HA structure. Consequently, the modified HA absorbed 16.3, 14.2, 10.6 and 6.9% more Pb, Ni, Zn and Cu, respectively, than the original natural HA. The isotherm data modeling together with adsorbent characterization suggested that the adsorption of PTTEs was controlled mainly by chemisorption mechanisms where inner-sphere complexations of metal ions with HA functional groups took place.

具有或不具有化学修饰的腐殖质可以作为环境中对环境无害且廉价的潜在毒性微量元素（PTTE）吸附剂。本研究通过分批实验研究了从低地泥炭中分离的天然和过硫酸钾（K ₂ S ₂ O ₈）改性腐殖酸（HAs）对Pb，Zn，Cu和Ni的吸收。Langmuir等温模型令人满意地描述了所研究的PTTE在天然HA上的吸附，其对Pb，Cu，Zn和Ni的最大单层吸附容量分别为318.2、286.5、225.0和136.8 mmol / kg。使用¹³对天然和修饰的HA进行全面表征C核磁共振波谱表明，用K ₂ S ₂ O ₈对天然HA进行化学修饰导致HA结构中羧基，酮和醌类碎片的含量增加。因此，与原始天然HA相比，改性HA分别吸收了16.3％，14.2％，10.6％和6.9％的Pb，Ni，Zn和Cu。等温线数据模型以及吸附剂表征表明，PTTE的吸附主要受化学吸附机制控制，其中金属离子与HA官能团发生内球络合。