The sorption of microquantities of Tm(III) ions on washed polyurethane foam (PUF) from a mixture of aqueous solution and ethanol
containing PAN was examined. The maximum sorption of 3.18. 10-6M solution of Tm(III) ions was observed at pH 8 with 30-minute equilibration time. The optimum ratio of aqueous-ethanol phase
for the sorption of Tm(III) ions was found to be 3:1 v/v, respectively. The sorption rate of metal ions on PUF is followed a first order kinetics and obeyed the equation for an intra
particle diffusion process. The equilibrium concentration data of Tm(III) ions could be described satisfactorily by several
adsorption isotherms. The Freundlich adsorption isotherm constants 1/nand KFare 0.66±0.02 and (5.7±0.3). 10-3mol. g-1, respectively. The Langmuir isotherm constants for monolayer coverage (Q) and binding strength of sorption (b) are (2.5±0.7). 10-5mol. g-1and (1.6±0.1). 104l. mol-1, respectively. The sorption capacity derived from Dubinin-Radushkevich (D-R) isotherm is (1.7±0.2). 10-4mol. g-1and the sorption free energy (E) is 9.8±0.2 kJ. mol-1indicating chemisorption phenomena. The thermodynamic parameters indicate that the sorption of Tm(III) ions onto PUF is endothermic,
entropy driven and spontaneous in nature.
A flow injection on-line determination of uranium(VI) after preconcentration in a minicolumn having amberlite XAD-4 resin
impregnated with dibenzoylmethane (DBM) is described. Uranium(VI) is selectively adsorbed from aqueous solution of pH 5.5
in the minicolumn (5.5 cm long with 5.0 mm i.d.) at a flow rate of 13.6 mL min−1. The uranium(VI) complex was desorbed from the resin by 0.1 mol dm−3 HCl at a flow rate of 4.2 mL min−1 and mixed with arsenazo-III solution (0.05% solution in 0.1 mol dm−3 HCl, 4.2 mL min−1), and taken to the flow through cell of spectrophotometer where its absorbance was measured at 651 nm. Various parameters
affecting the complex formation and its elution were optimized. Peak height (absorbance) was used for data analyses. The preconcentration
factors of 36 and 143, detection limits of 0.9 and 0.232 μg L−1, sample throughputs of 40 and 10 were obtained for preconcentration time of 60 and 300 s, respectively. The tolerance limits
of many interfering cations like Th(IV) and rare-earth elements were improved. The proposed method was applied on different
water (spiked tap, well and sea water) and biological samples and good recovery was obtained. The method was also validated
on mocked uranium ore sample and the results were in good agreement with the reported value.
A very sensitive and selective flow injection on-line determination method of thorium (IV) after preconcentration in a minicolumn
having XAD-4 resin impregnated with N-benzoylphenylhydroxylamine is described. Thorium (IV) was selectively adsorbed from aqueous solution of pH 4.5 in a minicolumn
at a flow rate of 13.6 mL min−1, eluted with 3.6 mol dm−3 HCl (5.6 mL min−1), mixed with arsenazo-III (0.05% in 3.6 mol dm−3 HCl stabilized with 1% Triton X-100, 5.6 mL min−1) at confluence point and taken to the flow through cell of spectrophotometer where its absorbance was measured at 660 nm.
Peak height was used for data analyses. The preconcentration factors obtained were 32 and 162, detection limits of 0.76 and
0.150 μg L−1, sample throughputs of 40 and 11 h−1 for preconcentration times of 60 and 300 s, respectively. The tolerance levels for Zr(IV) and U(VI) metal ions is increased
to 50-folds higher concentration to Th(IV). The proposed method was applied on different spiked tap water, sea water and biological
sample and good recovery was obtained. The method was also applied on certified reference material IAEA-SL1 (Lake Sediment)
for the determination of thorium and the results were in good agreement with the reported value.
The extraction behavior of nalidixic acid (HNA) in CH2Cl2 has been studied for various di- and trivalent metal ions such as Cu(II), Fe(II), Ni(II), Mn(II), Sb(II), Co(II), Sc(III),
Y(III), Nd(III) and Eu(III) from aqueous buffer solutions of pH 1–7 with 0.1 mol dm−3 nalidixic acid in dichloromethane. Separation factors of Sc(III) from these metals has shown that its clean separation is
possible at pH 3.4–4. The parameters affecting the extraction of Sc(III) were optimized. The composition of the extracted
adduct was determined by slope analysis method that came out to be Sc(NA)3. Extraction of Sc(III) was studied in the presence of various cations and anions. Among the anions studied only fluoride,
citrate and oxalate have significant interference whereas, Fe(III) has reduced the extraction to 53% that can be removed by
using ascorbic acid as reducing agent. The proposed extraction system proved good stability up to six extraction-stripping
stages for the extraction of Sc(III).
Drought is one of the major abiotic stresses that drastically reduces crop yield throughout the world. Being precursor of glutathione biosynthesis and involvement in other metabolic processes, cysteine (Cys) has been shown to alter growth and development in plants. In this context, we investigated Cys-induced physicochemical alterations in oat (Avena sativa L. var. Scott and var. F-411) plants under drought stress.
There were two levels of drought stress, i.e., control (100% field capacity) and drought (50% field capacity) and three levels of foliar application of Cys, i.e., 0, 10, and 20 mM. Experimental design was completely randomized block design.
Drought stress significantly decreased growth parameters, chlorophyll (Chl) contents, while increased leaf membrane permeability (MP), ascorbic acid (AsA), and activity of catalase (CAT) and peroxidase (POD) enzymes. Foliar application of varying Cys levels significantly increased root fresh weight, root length, photosynthetic pigments (chl. a and b), AsA contents in var. Scott, and shoot length, total free amino acids, total phenolics and free proline contents in var. F-411.
Of the two oat varieties, var. Scott proved better in root fresh weight, root length, chl. a and b contents, and total phenolic contents, while var. F-411 was higher in the values of shoot length, MP (%), total free amino acids, and free proline contents. Thus, on the basis of strong root system, total phenolics, and more photosynthetic contents (chl. a and b contents), var. Scott could be grown under semi-arid environments than that of var. F-411.
Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using
gamma ray spectrometric technique. 226Ra, 232Th, the primordial radionuclide 40K and the artificial radionuclide 137Cs have been measured in the soil of the study area. The mean radioactivity levels of 226Ra, 232Th, 40K and 137Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg−1 respectively. The mean radium equivalent activity (Raeq), outdoor radiation hazard index (Hout), indoor radiation hazard index (Hin) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg−1, 0.51, 0.65 and 70.1 nGy h−1 respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with
other global radioactivity measurements and are found to be safe for public and environment.