Enrichment of iron(III), cobalt(II), nickel(II), and copper(II) by solid-phase extraction with 1,8-dihydroxyanthraquinone anchored to silica gel before their determination by flame atomic absorption spectrometry

Abstract

A chelating matrix prepared by immobilizing 1,8-dihydroxyanthraquinone on silica gel modified with 3-aminopropyltriethoxysilane has been characterized by use of cross-polarization magic angle spinning (CPMAS) NMR, diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy, and thermogravimetric analysis and used to preconcentrate Fe(III), Co(II), Ni(II), and Cu(II) before their determination by flame atomic absorption spectrometry. The optimum pH ranges for quantitative sorption are 6.5-8.0, 6.0-7.0, 6.0-8.0, and 7.0-8.5 for Cu, Fe, Co, and Ni, respectively. All the metal ions can be desorbed with 2 mol L(-1) HCl or HNO3. The sorption capacity ( micromol g(-1) matrix) and preconcentration factor were 226.6, 250; 365.6, 300; 101.8, 150; and 109.0, 250 for Cu, Fe, Co, and Ni, respectively. The lowest concentration for quantitative recovery was 4.0, 3.3, 6.6, and 4.0 ng mL(-1), respectively for the four metal ions. The limits up to which electrolytes NaNO3, NaCl, NaBr, Na2SO4, and Na3PO4 and cations Ca(II) and Mg(II) can coexist with the four metal ions during their sorption without adverse effect are reported. The simultaneous enrichment and determination of all the four metals is possible if the total load of metal ions is less than the sorption capacity. Flame AAS was used to determine the metal ions in underground, tap, and river water samples (RSD<or=7.1%) after their enrichment with the matrix. The cobalt content of pharmaceutical samples (multivitamin tablet) preconcentrated by use of this silica gel matrix and determined by FAAS was found to be 2.00 microg g(-1), with RSDtilde;1.7% (reported concentration level, 1.99 microg g(-1)).

Cobalt and nickel uptake by silica-based extractants

“…[20] A wide range of organic materials have been attached to silica for the recovery of metals. Some examples include 1,8-dihydroxyanthraquinone for Fe(III), Co(II), Ni(II) and Cu(II) recovery, [21] imidazole, diaza-18-crown-6 and dibenzo-18-crown-6 for Co(II) sorption, [8] murexide for U(VI) preconcentration, [11] salicylaldoxime for Co(II), Ni(II), Co(II), Zn(II) and Fe(III) preconcentration [7] and gallic acid for Pb(II), Cu(II), Cd(II) and Ni(II) preconcentration. [9] Additionally, there are many commercially available polymeric-based resins and several silica-based resins that have been used to remove or recover a range of metal ions.…”

Adsorption and thermochemical data of divalent cations onto silica gel surface modified with humic acid at solid/liquid interface

“…Composites based on inorganic silica matrix and chelant organic pendant groups are one of the most used to remove metal ions from water and other solvents [12,13] due to the abundance, high thermal and chemical stabilities and specific bonding abilities of desired functional organic groups attached on silica surface [14][15][16][17].…”

Separation, preconcentration and determination of silver ion from water samples using silica gel modified with 2,4,6-trimorpholino-1,3,5-triazin

“…It has several advantages over other techniques, including stability and reusability of the solid phase, reach of high preconcenrtation factors, easiness of separation and enrichment under dynamic conditions, no need for organic solvents which may be toxic and minimal costs due to low consumption of reagents. Accordingly, several selective solid-phase extractors have been prepared by either physical loading or chemical binding of selected chelating reagents to different solid supports such as silica gel [14][15][16][17][18][19][20][21], activated carbon [22,23], cellulosic derivatives [24], polyurethane foam [25] and chelating ion exchange resins [26][27][28][29].…”