Many adsorbents have been studied for the removal of colorants from wastewater.  Substances examined include activated carbons prepared from numerous natural sources.  Other adsorbents which have been investigated include a variety of types of agricultural waste, mineral matter and industrial waste.  The attached link is to an excellent review that summarises the use of low-cost adsorbents in dye removal.

http://onlinelibrary.wiley.com/doi/10.1111/cote.12019/abstract

Lot of literatures available on functionalized adsorbents. Please refer.

Please refer K.F. Lam et al- Selective adsorbents from chemically modified ordered Mesopororous Silica. They used it for removing Dye and 9Heavy) Metal polluents from the water.

H-bonds, Electrostatic interaction and ion exchange.