“…However, it has some disadvantages including high cost, problems of regeneration, and difficulties of separation from wastewater (Wang et al 2009a, b;Zhang et al 2007). Recently, much attention has been paid to clay minerals such as bentonite (Zhao et al 2010;Ulusoy and Simsek 2005;Futalan et al 2011), attapulgite (Wang et al 2009a, b;Chen and Wang 2009;Zhao et al 2009), kaolinite (Unuabonah et al 2008a, b) and zeolite (Ulusoy and Simsek 2005) as low-cost adsorbents with high specific surface area, chemical and mechanical stability, and high cation exchange capacities (CEC). Colloidal dispersions of clays, however, can cause some difficulties hindering water flow (Keren and Ben-Hur 2003).…”