Sepiolite-Based Adsorbents for the Removal of Potentially Toxic Elements from Water: A Strategic Review for the Case of Environmental Contamination in Hunan, China

The last few decades have seen rapid industrialization and urban development in many regions globally; with associated pollution by potentially toxic elements; which have become a threat to human health and the food chain. This is particularly prevalent in a number of regions in China that host multiple mineral resources and are important agricultural locations. Solutions to protect contamination of the food chain are more effective and sustainable if locally sourced materials are available; and in this context; we review the potential of local (sepiolite) mineral deposits to treat water contamination in the Hunan Municipality; central south China; widely recognized for significant environmental pollution issues (particularly by Hg; Cd; Pb; and Cr) and the high agricultural productivity of the region. Sepiolite is an abundant fibrous clay mineral with modest to good adsorption properties and extensive industrial process applications. It shows reasonable performance as an adsorbent for element removal. In addition; a number of surface modification strategies are available that improve this capability. We review these studies; focused on sorption reaction mechanisms and regeneration potential; with a view to present options for a localized and effective economic strategy for future application.