A novel silica gel phase [Si-NH2-VB4] is synthesized by a direct immobilization of Vitamin B4 (VB4), as an eco-friendly modification of a silica-amine phase l[Si-NH2]. The resulting modified silica amine phase [Si-NH2-VB4] with VB4 showed a bi-character for selective extraction of both cation and anion species from aqueous media. Surface coverage value, thermal stability, structure identification and confirmation, as well as interaction properties, were determined using thermal desorption method, thermal degradation analysis by TGA and FT-IR. The adsorption study showed that [Si-NH2-VB4] has a good affinity for binding and extracting toxic oxyanions including chromate, arsenate and arsenite via the incorporated anion exchange character. [Si-NH2-VB4] also showed a tendency to have high selectivity towards extraction of Hg(II) ions from aqueous solutions in a wide range of pH-values due to different possible binding sites. Other metal ions, such as Cu(II) and Cd(II), were highly extracted at high pH-values due to a single site of interaction. Based on environmental water samples, the potential application of [Si-NH2-VB4] is for selective extraction of Hg(II) from aqueous media under a wide range of pH conditions. (C) 2011 Elsevier B.V. All rights reserved.