Layered Double Hydroxides for Soil and Groundwater Remediation

Abstract

Layered double hydroxides (LDHs), also referred to as anionic clay, are promising adsorbents for soil and groundwater remediation. As eco-friendly and low-cost materials, they can effectively remove/immobilize contaminants through their unique characteristics. LDHs have been extensively used in wastewater treatment. However, the application of LDHs in soil and groundwater is limited. This chapter first introduces the synthesis and characteristics of LDHs. The synthesis methods mainly include co-precipitation, urea-based method, salt-oxide method, ion exchange, and calcination. The unique characteristics of LDHs include memory effect and high anion exchange capacity. The interactions between LDHs and contaminants are then detailed, which lay the foundation of their environmental applications. LDHs can remove/immobilize anionic contaminants mainly through adsorption and intercalation, and cationic heavy metals mainly through precipitation. They can also aid the degradation of contaminants through serving as catalyst. Finally, the existing applications of LDHs in wastewater treatment serving as adsorbents and catalyst are introduced, and their potential applications in soil and groundwater is discussed. This chapter aims to give scientific researchers and industrial participators a broad view of LDHs and their applications in soil and groundwater remediation.