A systematic review of layered double hydroxide-based materials for environmental remediation of heavy metals and dye pollutants

Heavy metals and dyes are among the most hazardous industrial pollutants, posing a serious threat to the aquatic environment and human health. Therefore, simple and cost-effective methods for the environmental remediation of these pollutants are highly desirable. On the other hand, layered double hydroxides (LDH's) exhibited many distinctive characteristics including adjustable structure, simple synthesis procedures, stability, large surface area, and formation of various nanocomposites that conferred LDH's remarkable adsorptive capabilities towards various pollutants from wastewaters. Herein, we highlight the synthetic routes of LDH-based materials, their structural features, methods of physicochemical characterization, and their application in pollutants remediation. The impact of adsorption variables including adsorbent mass, temperature, pollutant concentration, contact time, and pH as well as various kinetic models and adsorption isotherms are also reviewed. The elimination mechanisms of heavy metals and dyes using LDH-based nanomaterials are discussed. In addition, the reusability of LDH's, the major challenges, the economic aspects of the treatment, and future perspectives are also highlighted.