功能化水热竹炭设计合成及对软酸型重金属离子吸附机理研究

Hydrochar prepared from bamboo and other materials is a kind of low-cost and environmentally friendly adsorbent, which can adsorb heavy metals by abundant oxygen-containing functional groups on its surface. However, low specific surface area and low adsorption capacity of oxygen-containing functional groups such as hydroxyl group for heavy metals restrict it to become an efficient adsorbent material. Chemical surface modification can effectively increase the species and density of functional groups on the surface of hydrochar, and significantly improve the adsorption capacity of hydrochar for heavy metals. The project aims at removing highly toxic soft heavy metal ions onto functional modified bamboo hydrochar by grafting soft base functional groups including thiosemicarbazide, xanthate, and heterocyclic on the surface of bamboo hydrochar, and improving the adsorption capacity and selectivity of functional modified bamboo hydrochar for specific heavy metal ions. The project combines macro-experiment (batch adsorption experiment), theoretical model (surface coordination model and ion exchange, etc.) and advanced spectroscopic instruments (XPS and EXAFS, etc.) to study the structure of adsorbent, the adsorption process and the microstructures of adsorbed metal ions (such as the types and number of coordination atoms, the distance between atoms and other related information). The comprehension of interaction between heavy metal ions and functional groups of adsorbents at the molecular level was to clarify the principle of adsorption/selective adsorption of functional bamboo hydrochar for heavy metal ions, and to provide theoretical basis for designing and synthesizing highly efficient and highly selective adsorbents for heavy metal ions.

利用竹材等制备的水热炭是一类成本低廉、环保的重金属吸附剂，但水热炭比表面积小和羟基等含氧官能团对重金属吸附能力较低，制约其成为高效吸附材料。化学表面改性能有效增加水热炭表面官能团的种类和密度，显著提高水热炭对重金属的吸附能力。本项目以高毒性“软酸”型重金属离子的除去为目标，将“软碱”基团（硫代氨基脲、含巯基杂环、含氨基杂环、原磺酸根等）修饰在水热竹炭表面，提高水热竹炭对目标重金属离子吸附容量和吸附选择性。项目以宏观实验（批吸附实验）、理论模型（表面配位、离子交换等模型）和先进光谱表征技术（XPS、EXAFS等）相结合的研究思路，深入研究吸附剂结构、吸附过程和被吸附金属离子的界面微观结构（如周围原子种类、配位数、核间距等相关信息），从分子水平构建重金属离子与吸附剂官能团的相互作用关系，从而阐明功能化水热竹炭对重金属离子吸附/选择性吸附原理，为设计合成高效高选择吸附重金属吸附剂提供理论依据。