Determination of rhenium in plant materials

Abstract

Metal ions are known to be absorbed and concentrated by plant biomass. In distinction from ionexchange resins, which usually contain monofunctional groups, polyfunctional compounds of biomass exhibit unique capacity of accumulating metal ions, sometimes unrelated to classical sorption. This property can be used for different technological, analytical, and biological purposes, including the extraction of metals from industrial wastewater, cleaning contaminated areas, exploration of ore deposits (as biochemical indicators), etc.The scanty available data indicate that the concentration of rhenium in plants exceeds its concentration in the earth's crust by three to four orders of magnitude [1,2], which corresponds to anomalous accumulation, according to the currently accepted classification [3].Search for new sources of rhenium, including unconventional ones, is a burning problem because of the low rhenium concentration in the earth's crust (its clarke is 1 × 10 -7 %) and the great importance of this element for industry (aerospace, nuclear, electronic, oil-processing, and other). Of current interest is also the development of procedures for determining rhenium in plant materials in a wide concentration range and the thorough monitoring of the plant cover of different geographic regions, which is an essential condition for the detection and registration of anomalous biogeochemical fields of rhenium mineralization and the revelation of correlations between the concentrations of rhenium in water, soils, and plants. The information gained can be used in biotechnology and ecology to study rhenium effect on living organisms and the identification of rhenium species responsible for its migration, immobilization, and distribution in the nature.The aim of this work was to develop procedures for the determination of rhenium in plant biomass that are suitable for stationary and field conditions. It is known that the limiting step of routine analyses is sample preparation, which should not only ensure the complete conversion of the analyte to appropriate species but also meet the requirements of the method selected. Therefore, special attention was given to different methods for the decomposition of plant materials and to the distribution of rhenium among the steps of sample preparation. The radioactive 186 Re tracer was used.Rhenium was determined using catalytic methods based on the redox reactions of Sulfonitrazo R ( c min = 0.2 ng/mL) [4] and dimethyldithiooxamide ( c min = 1 ng/mL) [5] that we had developed previously, as well as solid-phase spectrophotometry ( c min = 0.1 µ g Re) [6] and neutron activation analysis. EXPERIMENTAL Apparatus. Experiments were conducted using a programmable PDP-18M furnace with two chambers (evaporation and ashing), a Specord M-40 spectrophotometer, and a single-channel NC-428B nuclear analyzer (Hungry) with a γ detector (model no. 35 114 059).Reagents. The stock solution of rhenium (1000 µ g/mL) was prepared by dissolving 0.1553 g KReO 4 in 100 mL of water; working solutions containing 1 µ g...

Synthesis of guanidine-containing copolymers and their applications in the sorption of transition metals

“…The content of Re(VII) in saturated solutions was determined by using titrimetric analysis with SnCl 2 . [15] Concentration of the SnCl 2 ·2H 2 O solute was determined as per the known method. [16] Milligram concentrations of Re(VII) were determined by using photometrical method while determining residual rhenium contents in the rhodanide complex.…”

“…In diluted solutions of acids and alkalis, the Re(VII) is present as a weakly hydrated perrhenate ReO 4 À ion. [15] The profiles of the pH value's influence on the sorption degree of rhenium for sorbents are represented in Fig. 7.…”

Extraction of rhenium (VII) by tetraoctylammonium bromide mixed with low-melting thinners

“…The most widespread method is liquid extraction. Similar to aqueous solutions, rhenium in a wide range of acidity of the aqueous phase is in the form of stable perrhenate ion (Borisova and Ermakov 1974 ); neutral and anion-exchange extractants are used for its extraction.…”

“…Effective extractants for rhenium are neutral organophosphorus compounds, di(izo)(octyl)metylphosphonate (Travkin et al 1975, Adamova and Ponomareva 1980, Chekmarev et al 1999, Palant et al 2007 ), tri-n -butylphosphate (TBP) (Travkin et al 1975, Adamova and Ponomareva 1980, Chekmarev et al 1999, Palant et al 2007, their derivatives hexabutyltriamide of phosphoric acid, alkyl phosphine sulfi des (Travkin et al 2003a,b ), synergistic mixtures of TBP with trioctylphosphine oxide or di-2-etylhexilphosphoric acid (Palant et al 2007 ), and oxygen-containing reagents (alcohols, ketones) (Borisova and Ermakov 1974, Chekmarev et al 1999, Palant et al 2007, Kassikov and Petrova 2009 ). To increase the solubility of the extraction reagents and extracted compounds in the solvents, up to 25 % vol.…”

“…Combined techniques described in the literature involve determination of rhenium by different methods in the aqueous phase after its re-extraction (Borisova and Ermakov 1974, Travkin et al 1975, Chekmarev et al 1999, Palant et al 2007. However, analysis is labor-and time-consuming owing to duration of separation of organic and aqueous phases and an additional stage of re-extraction.…”