Removal of reactive dyes using organofunctionalized mesoporous silicas

Mesoporous inorganic-organic hybrids with mono- or bifunctional pendant chains anchored onto the silica backbones were investigated for reactive dye removal. The organofunctionalized silicas obtained from silylating agents contain the functional groups: 3-aminopropyl, octadecyldimethyl(silylpropyl) ammonium and 3-mercaptopropyl. The pendant electrophilic chains attached on the new porous silicas interact with the negative charge of industrial textile reactive dyes: yellow GR, red RB and blue RN. The best maximum sorption results were obtained for both mercapto and amino groups, to give 351, 388 and 203 mg g-1 for GR, RN and RB dyes. These silicas also have the advantage of undergoing sorption without initial pH adjustment and surface saturation in short times. The high sorption capacity is due to the combination of properties associated with higher pore volume, surface area, smaller particle and the presence of two different functional groups, also emphasizing the presence of one mercapto group in the hybrid. These silicas, mainly the structurally bifunctional arrangement, with available disposition of pendant chains, are promising for textile effluent removal. © 2013 Springer Science+Business Media New York.