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Immobilized Biomass: A New Class of Heavy-Metal Selective Ion Exchangers
Published in Arup K. Sengupta, Ion Exchange Technology, 2021
Edward M. Trujillo, Mark Spinti, Hanna Zhuang
The diffusion coefficient for sodium in the particle phase was fixed at 1.6 X 10−6 cm2/sec, and the calcium and magnesium particle phase diffusion coefficients were evaluated by fitting binary experimental data. The particle phase diffusion coefficients used were 6.0 X 10−8 cm2/sec for calcium and 2.5 X 10−7 cm2/sec for magnesium. Rao et al. [126] studied the exchange of calcium and lead on CHELEX 100 resin. They reported a film mass-transfer coefficient of 0.0034 cm/sec for cadmium and 0.005455 cm/sec for lead. The corresponding effective particle phase diffusivities were 25-30 X 10−7 cm2/sec for cadmium and 75-90 X 10−7 cm2/sec for lead [126]. Robinson et al. [137] estimated film mass-transfer coefficients using several correlations and the short bed adsorber (SBA) developed by Weber [133,138]. The film mass-transfer coefficients determined by Robinson et al. using the SBA were 0.0052 cm/sec for calcium, 0.0053 cm/sec for strontium, 0.0038 cm/sec for magnesium, and 0.0081 cm/sec for cesium [137].
Determinative Techniques to Measure Organics and Inorganics
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
By evolving from a low-pressure (gravity fed) large-column-diameter (>1 cm) ion exchange chromatography (IEC) technique to a moderately high-pressure, narrow-column-diameter (~5 mm) high-performance IEC technique! The use of glass columns packed with either a strong or weak anion or cation exchange resin is routine in many chemical laboratories. However, the development of IC as an additional determinative technique is very useful to TEQA and requires that we discuss these principles. But first, as a way to review some principles of conventional IEC, let us discuss an ingenious use of two chemically different ion exchange resins and the simple experiment that can illustrate very nicely the principle of ion exchange (IE). One of the most useful IE resins is Chelex-100 whose molecular structure is shown below; it is a 1% cross-linked, 50 to 100 mesh, styrene–divinylbenzene resin containing iminodiacetate.
Adsorption and Ion-Exchange Processes
Published in Thomas E. Carleson, Nathan A. Chipman, Chien M. Wai, Separation Techniques in Nuclear Waste Management, 2017
These types of ion-exchange resins are typically commercially produced. However, there have been a large number of resins produced in small quantities by various researchers. The synthesis and use of this type of resin has been reviewed, both by Millar and coworkers35 and by Eccles and Greenwood.36 The use of chelating resins for analytical chemistry purposes was reviewed by Myasoedova, Savvin, and Vernadsky in 1986.37 There are a number of desirable properties that form the basis for the synthesis of this type of resin. The major properties are high metal capacity, high selectivity, fast kinetics, and high mechanical strength. There are basically four groups of commercial resins available today, each containing one of the following groups: iminodiacetic acid, aminophosphonic acid, amidoxime, or thiol.36 Typical commercial resins with these functional groups are Amberlite IRC-718 or Chelex-100®, which contain iminodiacetic acid groups (Chelex is supplied by Bio-Rad Chemical Division), Duolite C-467 with aminophosphonic acid groups, Duolite C-346, which contains amidoxime groups, and Purolite® S-920 or Duolite GT-73 with thiol groups.35 (Duolite is a trademark of DISA Limited, U.K. and Purolite is carried by Rohm and Haas Co.; resins are from Purolite Co.) The cost of synthesizing these types of resins is substantially higher than that of ordinary ion-exchange resins. Perhaps it is this higher cost that limits the number of different commercial chelating resins currently available.
Development of Tracer Particles for Positron Emission Particle Tracking
Published in Nuclear Science and Engineering, 2023
Thomas Leadbeater, Andy Buffler, Michael van Heerden, Ameerah Camroodien, Deon Steyn
Chelex-100 anion ion exchange resins30,32,42 and gamma-phase alumina (γ-Al2O3) have been demonstrated to be particularly efficient in producing 18F-based resin cores.43–45 At PEPT Cape Town,46 the strong-base anion exchange resins Purolite A200 and A870 are used. These consist of very small porous beads with quaternary ammonium cation functional groups attached to the styrene divinylbenzene copolymer lattice. These anion exchange resins are typically in chloride form where chloride is the counterion to be exchanged with 18F−. However, because the affinity of the 18F− ion to the functional groups is predominantly weaker than the Cl⁻ ion, the resin particles must first be converted into fluoride or hydroxide form. The conversion is achieved by rinsing the resin slurry with 8 to 10 bed volumes of 1 M KF solution to displace the Cl− counterions with F− ions before rinsing with 10 bed volumes of deionized water to remove the K+ and any unbound F− ions. Radiolabeling proceeds as described above, starting from 18F− ions dissolved in pure water, with the resin substrate undergoing further physical modification after production to match particle properties as detailed above.
Potential separation of zirconium and some lanthanides of the nuclear and industrial interest from zircon mineral using cation exchanger resin
Published in Journal of Dispersion Science and Technology, 2022
H. E. Rizk, A. M. Shahr El-Din, E. M. El Afifi, Mohamed F. Attallah
This can be attributed to the higher sorption capacity of the Amberlite IR-120 resin relative to Chelex-100.[27,28] Also, it is noticed that the polystyrene matrix in resin is functionalized by strongly sulfonic acid group (-SO2OH), whereas the weak iminodiacetic groups (-N(CH2COOH)2) exist in the Chelex-100. Moreover, the dissociation constant (Ka at 25 °C) of these moieties is 1.047 × 10−3 and 1.995 × 10−1 for iminodiacetic and sulfonic, respectively.[29] As a result, moieties of sulfonic groups in Amberlite-120 resin are more dissociable and reactive, i.e., stronger rather than acetic moieties in Chelex-100 resin. Thus, the capacity of Amberlite IR-120 is more than 2.5 folds of Chelex-100. Moreover, the high selectivity of the Amberlite IR-120 toward La3+ ions compared with Zr4+ ions may be due to variations in the physicochemical characteristics of both metal ions in solution such as aqua complex, metal-oxide bond distance (M–O, Ǻ), ionic radii (Mn+, Ǻ), coordination number and configuration,[30,31]Table 3. Due to economic and practical reasons, separation of La3+ and Zr4+ can be achieved from the binary acidic solution, especially 0.01 mol. L−1 HCl solutions rather than aqueous, alkaline, HNO3 or HClO4. The value of SF between La and Zr was high and reached about 2.1 × 103 as shown in Figure 3.
Integrated approaches to assess water quality in two spots along the western Mediterranean Sea, Egypt
Published in Chemistry and Ecology, 2021
Gehan Mohamed El Zokm, Mohamed Abdel Aziz Okbah, Essam Khamis El-Shorbagi
Water temperature and salinity were measured using CTD (YSI: 566). Dissolved oxygen and biochemical oxygen demands were determined according to the classical Winkler's method modified by Grasshoff et al. [15]. Chemical Oxygen demand (COD) was measured according to Soto et al. [16]. Oxidisable organic matter (OOM) was determined using permanganate values test [17]. Chlorophyll-a in water samples was extracted with 90% acetone [18] and measured spectrophotometrically using the SCOREUNESCO equation given by Jeffrey and Humphrey [19]. NO2-N, NO3-N, PO4-P and SiO4-Si and NH4-N were measured by using a Shimadzu double beam spectrophotometer UV-150-02 [15]. Dissolved metal ions preconcentration was performed using ion exchange resin (Chelex-100) [20, 21]. Metals were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Milli-Q water was used for sample standard preparation. Total phenol was estimated colorimetry using 4-aminoantipyrine by the method modified by Cun-guang [22].