Modification of mesoporous silica magnetite nanoparticles by 3-aminopropyltriethoxysilane for the removal of Cr(VI) from aqueous solution

A Mild and Facile Synthesis of Amino Functionalized CoFe2O4@SiO2 for Hg(II) Removal

“…It can be seen that the three materials all have typical characteristic peaks of Fe–O bonds at 588 cm −1 , and these peaks gradually weaken with the increasing thickness of the silicon shell. Adsorption bands at 3440 cm −1 and 1640 cm −1 are related to the silanol groups in −OH groups and the adsorption of water molecules, respectively [ 20 , 26 ].…”

Recent advances in hexavalent chromium removal from aqueous solutions by adsorptive methods

“…Due to the complex nature of Cr(VI)-adsorbent interactions mentioned earlier, researchers have found ways to capitalize on the different interactions by producing adsorbents that address two or more mechanisms. Adsorption-reduction mechanism has been exploited by many researchers, 16,29,30,147,148,158 and examples from the literature are detailed below. Another synergistic Cr(VI) removal methods are the adsorption/catalysis/reduction.…”

“…18,72,164,165 Several studies have accounted for the reduction of Cr(VI) during adsorption 3,4,16,30,32,166,167 while others have ignored. 21,54,92,147,148,158,168,169 Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy (XPS) has been used to account for the presence or absence of Cr(III) in the surface of adsorbents aer adsorption. 15,16,29,30 Atomic absorption spectroscopy can be used to account for Cr(III) in solution even though it does not measure it directly but rather calculated from the total chromium determination.…”

“…15,23,30,65,158,167 The choice of the desorbing agent used in desorption is based on the nature of the adsorbent surface functional groups, types of bonding interaction and the adsorption mechanism. 148 Araghi et al 148 used sodium hydroxide for chromium desorption as it led to deprotonation of -NH 3 + groups on the adsorbent surface which subsequently resulted in the decrease of electrostatic interactions between these groups and HCrO 4 À . 148 In Table 1, the number of repeated use shown indicate the minimum re-usability experiments performed in each case.…”

Environmental and biomedical applications of iron oxide/ mesoporous silica core-shell nanocomposites

“…Fourier transform infra-red spectroscopy (FTIR) is used to identify the functional groups in the nanocomposite. The peak at 1636 cm -1 is due to the physisorbed water, and the large stretch at 1000-1250 cm -1 is due to the Si-OH and Si-O-Si vibrations 208 . The characteristic peaks of hematite are seen in the FTIR spectra 24 .…”