层状双金属氢氧化物吸附剂的功能化改性策略

Functional modification strategies of layered double hydroxide adsorbents

摘要:

层状双金属氢氧化物（LDHs）是一类阴离子交换能力强、可调性好、热稳定性高、活性位点丰富的纳米吸附材料，在水中污染物的吸附去除方面呈现出巨大潜力。然而，官能团和结构组分的缺陷严重限制了原始LDHs的吸附性能和应用范围。利用不同改性策略对LDHs进行功能化处理，能显著增强LDHs的污染物吸附容量、选择性、稳定性、可回收性以及适用范围。该文从LDHs吸附水中污染物性能的优化出发，重点综述了当前常用的插层、表面修饰、煅烧、复合组装、包埋、制膜等LDHs功能化改性策略，总结了其与水中各种污染物（无机非金属阴离子、重金属离子、染料以及抗生素）之间的作用机理。此外，还阐述了相应的再生手段。最后，简要提出了功能化LDHs吸附剂的优势以及后期研究可能面临的障碍，并对其广阔的应用前景进行了展望。

Abstract:

The study of economic, green, and efficient sewage treatment methods has been a major challenge for the water treatment industry due to the complex nature of wastewater and the increasing demand for clean water supply. Layered double hydroxides (LDHs) are a kind of anionic clay with strong anion exchange capacity, good adjustability, high thermal stability, and rich active sites. As a class of adsorption materials, it has been widely used to adsorb various pollutants in wastewater and shows excellent removal performance. However, the defects in functional groups and structural components severely limit the adsorption performance and application range of pristine LDHs. The functionalization of LDHs with different modification strategies can significantly enhance the pollutant adsorption capacity and selectivity, stability, recyclability, as well as application scope. Based on the optimization of the performance of LDHs in the treatment of pollutants in wastewater, this review focuses on the commonly used functional modification strategies of LDHs, such as intercalation, surface modification, calcination, composite assembly, entrapment, and membrane preparation. The intercalation and surface modification treatment increases the number of special functional groups and promotes the selective adsorption of LDHs for target pollutants. The calcination treatment increases the adsorption efficiency of LDHs for anionic pollutants. And the efficient separation and recovery of LDHs can be realized by other methods, such as composite assembly, entrapment, and membrane preparation. Subsequently, the interaction mechanism between functionalized LDHs and various inorganic non-metallic anions, heavy metal ions, organic dyes, and antibiotic pollutants in wastewater was summarized. In addition, the regeneration methods of functionalized LDHs were also described. Finally, the advantages and the possible obstacles of functionalized LDH adsorbents in the next study were briefly proposed, and its broad application prospects were provided.