黏土酸浸废液合成层状双金属氢氧化物及其除氟性能

Synthesis of Layered Double Hydroxides from Spent Acid-Leaching Solution of Clay and Their Fluoride Removal Performance

摘要: 以杭锦凹凸棒石盐酸酸浸废液为金属离子源，采用共沉淀法制备层状双金属氢氧化物(LDH)，考察沉淀剂及共沉淀pH值对LDH结构、理化性质和氟离子吸附性能的影响。结果表明，以氢氧化钠为沉淀剂、pH约为8时制备的MgAlCaFe-LDH展现出优异的除氟性能，对初始浓度为10 mg/L和50 mg/L的氟离子溶液的去除率分别可达95.45%和93.92%，且受溶液pH值影响较小，吸附氟离子过程符合Langmuir吸附等温线模型和拟二级动力学模型，最大吸附容量57.47 mg/g。最后，采用多种表征手段探讨其除氟机理。研究不仅为低质混维黏土矿物的资源化、高值化利用提供了可行路径，也为开发经济高效的氟吸附材料拓展了新思路。

Abstract: Layered double hydroxides (LDH) were prepared by the co-precipitation method with Hangjin attapulgite hydrochloric acid leaching waste liquid as a metal ion source. The effects of precipitant and co-precipitation pH on the structure, physicochemical properties, and fluoride ion adsorption properties of the LDH were investigated. The results show that MgAlCaFe-LDH prepared with sodium hydroxide as precipitant and a pH of about 8 exhibits excellent fluoride removal performance. The removal efficiency of fluoride ion solutions with initial concentrations of 10 mg/L and 50 mg/L can reach 95.45% and 93.92%, respectively, and are less affected by the pH value of the solution. The adsorption process of fluoride ions conforms to the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model, and the maximum adsorption capacity is 57.47 mg/g. Finally, a variety of characterization methods were used to explore the fluoride removal mechanism. This study not only provides a feasible path for the resource and high-value utilization of low-quality mixed-dimensional clay minerals, but also expands new ideas for the development of economical and efficient fluorine adsorption materials.