Ionic conduction in sepiolite

Determination of adsorptive properties of a Turkish Sepiolite for removal of Reactive Blue 15 anionic dye from aqueous solutions

“…For this purpose, the cheap and efficient alternate materials including clays as sepiolite, etc., are used because of their high-specific surface area, high adsorption capacity, microporous structure. The sepiolite is a clay mineral with an ideal formula Mg 8 Si 12 O 30 (OH) 2 and also the unit cell of the sepiolite corresponding to the orthorhombic system consists of microchannels [11][12][13]. This mineral is commonly used as adsorbents, fillers, colour changing agent, catalyst or catalyst supports [14][15][16].…”

“…Mobile cations in the SiO 4 tetrahedral sheet (Al 3+ and Fe 3+ ) and MgO 6 octahedral sheet (Fe 2+ , Fe 3+ , Al 3+ , Mn 2+ and Ti 2+ ) and exchangeable ions (Ca 2+ and Mg 2+ ), and variable amounts of zeolitic water in the ideally rectangular channels give rise to high surface areas and structural changes [11,13,[16][17][18].…”

“…2) may be summarized as follows: (i) the band of the triple bridge group Mg 3 OH is at 3697 cm −1 , (ii) the absorption of the structurally bound water is seen at 3591 cm −1 and (iii) the stretches at the 3620 and 3451 cm −1 and the OH-bending mode at 1660 cm −1 are associated with zeolitic water. The lattice vibrations are given as follows: (a) the Si-O combination bands at 1213, 1090 and 987 cm −1 , (b) the basal plane of the tetrahedral units exhibiting the Si-O-Si plane vibrations at 1019 and 474 cm −1 , (c) the feature at 442 cm −1 arising from the Si-O-Mg of the octahedral-tetrahedral linkage and (d) Mg 3 OH-bending vibration at 655 cm −1[11,24]. Dolomite impurities give rise to the 1440 cm −1 band[13].…”