Layered Double Hydroxides in the Remediation and Prevention of Water Pollution

Increasing efforts are being made worldwide to prevent pollution, and where it has arisen to remediate the effects. A particular concern is ensuring the purity of water supplies. Layered double hydroxides (LDHs) and their calcined products (CLDHs) have received much attention in this regard. By dint of their ability to undergo anion exchange, surface adsorption, reconstruction, and adsolubilization, these materials have great potential in the removal of pollutants from effluvium streams, and/or to provide sustained and targeted release of functional anions. They can also be used as catalysts or catalyst supports. A range of wastewater clean-up technologies have been proposed applying LDHs and CLDHs as sorbents and catalysts. This review outlines the latest research into the use of these materials in water treatment. The direct uptake of pollutants through ion exchange, reconstruction and adsolubilization are considered in detail, followed by the use of LDHs and CLDHs as catalysts for pollutant degradation. Finally, the possible roles of LDHs and CLDHs in advanced formulations to deliver agrochemicals in a sustained manner, thereby preventing leaching and eutrophication, are considered.