Solid-phase Extraction of High Oxidation State Metal Ion-Desferrioxamine B Chelates Using Sulfuric Acid-treated Silica Gel

Abstract

Many types of ion exchange resins and chelate resins such as polystyrenes, 1-4 polyvinyl resin, 5 polyacrylate 6 and silica gels [7][8][9][10] were used for the solid-phase extraction of metal ions. Especially, silica gel has been widely applied as an ion exchange support for cationic species such as metal ions and cationic metal-chelates, because silica gel has many silanol groups on its surface. However, many solid-phase extraction methods using silica gel are based on the ion exchange reaction of the silanol group. Thus, it was very difficult to extract metal ions and/or metal-chelates which were only generated in a strong acidic aqueous solution. On the other hand, chemically modified silica gels such as octadecyl silicate (ODS) were developed to extract not only cationic compounds but also neutral and/or negatively-charged compounds. However, in strongly acidic media, it was also difficult to extract the cationic compounds. Moreover, when the modified group was released, these supports could not be recycled.In searching for a support which can be used in a strongly acidic media and then recycled, we found that a silica gel which had been heated in concentrated sulfuric acid acts as an effective ion exchange support for cationic compounds in acidic aqueous solution.On the other hand, the authors have already reported that desferrioxamine B (DFO, Fig. 1), one of the hydroxamate type siderophores, specifically reacts and forms chelates with seven high oxidation state metal ions {Ti(IV), Zr(IV), V(V), Nb(V), Ta(V), Mo(VI) and W(VI)}. Homogeneous liquid-liquid extraction of these metal-chelates was then developed. 11 In this paper, the solid-phase extraction of these metal-chelates from strongly acidic aqueous solution using sulfuric acid-treated silica gel was studied. Experimental Materials and apparatusSilica gel (for thin layer chromatography, particle size: <46 µm) was received from Wako Pure Chemicals. Sulfuric acid and hydrochloric acid were purchased from Kanto Chemicals. Desferrioxamine B was obtained from Ciba-geigy as its methanesulfonate salt. Each metal ion standard solution (1000 ppm) was obtained from Kanto Chemicals. All other reagents used were of analytical reagent grade as received from Kanto Chemicals, unless otherwise described.A Nippon Jarrell-Ash ICAP-575 instrument was used for the ICP atomic emission spectrometry (ICP-AES). A JASCO Herschel FT/IR-410 instrument was used for the FT-IR. Preparation of sulfuric acid-treated silica gelA 40-cm 3 volume of sulfuric acid was added to 10 g of the silica gel and the mixture was then heated at 120˚C for 30 min. After heating, the silica gel was filtered to remove the sulfuric acid. Here, 5 different samples of the sulfuric acid-treated silica gel were prepared under the proposed condition and then solidphase extraction of the V(V)-DFO chelate was performed. As a result, 3.8% of relative standard deviation was obtained. It clearly shows that these silica gels have the same performance. The obtained sulfuric acid-treated silica gel was stored in a d...

Adsorption behaviors of high-valence metal ions on desferrioxamine B immobilization nylon 6,6 chelate fiber under highly acidic conditions

“…Therefore, it was obviously understood that the metal-DFB complex was extracted. Some of the DFB complexes with high-valence metal ions have been known [13][14][15]. We further attempted the synthesis of chelate fiber for the adsorption having selectivity.…”

Synthesis and Evaluation of Reusable Desferrioxamine B Immobilized on Polymeric Spherical Microparticles for Uranium Recovery

“…In particular, the formation of DFO complexes with high-valence radionuclides such as U, − Pu, and Th has been studied. Moreover, the combination of DFO with solid-phase bases, including cellulose paper, 6,6-nylon fiber, and silica gel, for analytical applications has been reported. However, the incorporation of DFO on particles with specific sizes and uniform spherical shapes at the surface of polymers still constitutes a challenge owing to chain polymerization and/or the deactivation of the metal chelating site of DFO.…”