插层法腐殖质/粘土复合材料制备及对典型污染物去除特性和机理

Humus/clay complex(HCC) can offset the emerging disadvantages when humus and clay are used as absorbent separately, and can be used to control organic combined inorganic pollutants, thus, it has a wide application prospect in environmental protection area. Commonly, HCC was prepared using macromolecular humus, and stable HCC with humus embedded into clay’s interlayer as well as with high composite degree could not be obtained, which restrain the application of HCC. Based on the abiotic humification theory of low molecular precursors and the phenomena that low molecular precursors can intercalate into the interlayer space of clay. Therefore, an intercalating process start with low molecular precursors of humus to prepare HCC is proposed in this study, and the relevant studies include the mechanism of the process, influence and optimization of environmental factors during the process; the microscopic features of HCC; the performance of HCC during application, which includes thermal stability, composite degree between humus and clay, and resistance to environmental impact; the environmental risk assessment of HCC based on the static extraction and the dynamic column leaching experiment; the efficiency and mechanism of HCC to remove typical pollutants. Ultimately, an intercalating process to prepare HCC with well-established intercalation mechanism，clearly defined effect of influence factors on intercalation and optimized operation parameters would be developed, and more stable and environment-friendly HCC with better adsorption capacity will be produced. The achievements of this study will provide the theoretical and experimental basis for the application of HCC in environmental protection area.

腐殖质/粘土复合材料（HCC）能够避免粘土、腐殖质单独作为吸附剂在污染物去除方面的局限和不足，并可用于有机-无机复合污染物控制，在环境治理领域具有广阔应用前景。然而，传统制备方法以大分子腐殖质为原料，无法制得腐殖质嵌入粘土晶层、复合强度更高的HCC，从而限制了其推广应用。基于小分子前体物非生物腐殖化理论，本课题提出以小分子前体物为起点的HCC插层法制备工艺，系统开展理论研究和应用评估，包括研究HCC插层法制备工艺机理、影响因素及工艺条件优化，分析HCC微观特征、热稳定性、腐殖质-粘土复合强度以及抗环境冲击性，通过静态浸提和动态淋滤模拟不同情景下HCC的环境安全性，在上述基础上研究HCC对典型污染物的去除特性和机理，从而形成插层机理清晰、影响因素明确、制备条件优化的HCC插层法工艺及性质更为稳定、吸附效果更佳、环境友好的新型HCC，为插层法HCC在环境治理领域的推广应用奠定理论和实验基础。

我国当前的水体污染形势严峻，以含毒性金属和难生物降解有机物为主要污染特征，生物毒性强，而开发高效、适用性强的环境功能材料用于水体污染治理成为当前的研究热点。腐殖质/粘土复合材料（HCC）能够避免粘土、腐殖质单独作为吸附剂在污染物去除方面的局限和不足，在环境治理领域具有广阔应用前景。本研究基于腐殖质和水滑石（LDH）的特殊性质，以及小分子前体物形成腐殖质大分子的非生物腐殖化理论，开发了性质更为稳定、吸附效果更佳的新型腐殖质/粘土复合吸附剂。主要研究成果如下：.（1）采用“离子交换-焙烧-水化复原”的方法合成了腐殖化催化剂Fe3O4柱撑LDH. Fe(C6H4O7)- 阴离子插层LDH在550 ℃焙烧1 h使Fe(C6H4O7)-氧化生成Fe3O4，通过在0.015 M HNO3-30 wt% NaNO3混合溶液中水化复原，得到新型腐殖化催化剂纳米Fe3O4镶嵌LDH，其层间域为可交换的NO3-。.（2）前体物儿茶酚和甘氨酸通过Fe3O4柱撑LDH的原位催化腐殖化反应，自组装合成了三明治结构的类腐殖质（HLS）负载水滑石复合吸附剂（LDH-HLS），其过程机理包括小分子扩散、原位腐殖化并负载、液相腐殖化并负载和固体表面腐殖化四个阶段。儿茶酚为腐殖化主要前体物，儿茶酚氧化环裂并进一步缩聚形成大分子HLS。较优的非生物腐殖化自组装条件为：前体物浓度001M，固液质量比1:7.5，pH 7-8，反应时间24-72h。.（3）在不同有机负荷和pH下，经Fe3O4柱撑LDH的原位催化腐殖化反应生成的HLS性质差异不大，分子量较小（1000-2000 g/mol），聚合程度不高，与重金属络合时的空间位阻较小，而酸性官能团高达8.5 mmol/g（天然FA为3.31 mmol/g），提供更多的配位络合吸附位点，同时保留了LDH的层片状结构，在pH为2-11的范围均带负电，有利于吸附阳离子型污染物。.（4）与通过LDH晶核在共沉淀过程中的混凝以及富里酸大分子（FA）的吸附架桥作用合成的富里酸锚接水滑石多功能复合吸附剂（LDH-FA）相比，LDH-HLS对Pb2+、Cd2+和Ni2+的亲和力显著升高，对Cu2+的亲和力小幅降低，对四种重金属吸附速率加快，吸附性能更佳。