Abstract
Abstract The use of functional material can help mitigate the pollution by heavy metals, which presents an array of risks to human production and life. This work provides a comprehensive review of the current knowledge on functionalized layered double hydroxide (LDH) as a heavy metal absorption material, by synthesizing the information from a total of 141 relevant publications published since 2005. LDH provides a potentially highly efficient method to adsorb heavy metal ions, which is simple to prepare and of low cost. The lack of functional groups and structural components of pristine LDH, however, limits the absorption capacity and widespread applications of LDH. Through intercalation, surface modification, or loading on substrates, functional groups or structural components are introduced into the pristine LDH to prepare functionalized LDH. In this process, the hydroxyl group and the valence state of [Mg(OH)6] octahedrons play a crucial role. Functionalized LDH can be endowed with selective absorption capacity and enhanced stability and recyclability. After adsorbing heavy metal ions, functionalized LDH can be readily separated from the liquid phase. These aspects are discussed, along with the structure and composition, shape and size, and synthesis methods and research tools of LDH. This work concludes with the discussion of preparation and utilization and a look to the future in terms of identified research needs regarding the preparation, use, and recycling (or upcycling) of economical and environmental-friendly LDH.
Highlights
The pollution of natural environment by heavy metal ions is a ubiquitous issue with dire consequences
The main purpose of this study is to provide a comprehensive review of the current knowledge on functionalized layered double hydroxide (LDH) as heavy metal ion absorption material
Yang et al studied the effect of MgAl–LDH particle size on the absorption performance of As5+, and the results show the absorption rate of MgAl–LDH increases while the particle size decreases, but the absorption capacity does not change significantly [39]
Summary
The pollution of natural environment by heavy metal ions is a ubiquitous issue with dire consequences. Heavy metals with a density greater than 4.5 g/cm, such as Hg, Cr, Ni, Fe, Cu, Zn, and Mn, are closely related to human production and life. Heavy metals are widely used in electronic components, antibacterial materials, batteries, photosensitive materials, etc. If the heavy metals are not properly disposed, they may cause many environmental or health risks [1]. Heavy metals affect the growth of organisms and plants in water and become enriched in aquatic organisms and plants [3]. Heavy metal ions accumulate in the human body through the food chain and drinking water, thereby threatening human health [4]
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