Vinod K. Singh

Radiotracer technique in adsorption study: Part XIV. Efficient removal of mercury from aqueous solutions by hydrous zirconium oxide

Adsorption of Hg(II) ions on synthetic hydrous zirconium oxide has been investigated as a function of contact time, Hg(II) concentration (10−3−10−8 M) and temperature (303–333 K). x-Ray diffraction studies indicated the amorphous nature of the synthesized oxide. The relative change of uptake, i.e. percentage adsorption increases from 80.3 to 98.3% with the increase in dilution (from 1.0 × 10−3 to 1.0 × 10−8 M). The kinetics of the process follows first order rate law and obeys the Freundlich isotherm over the entire range for the bulk concentration of Hg(II). The uptake of Hg(II) increase in temperature from 303 to 333 K. Pre-irradiation of adsorbent with neutrons (3.85 × 106 n/cm2/s) and γ-radiations (ca 1.72 Gy/h) has practically no effect on the extent of adsorption of Hg(II).

Efficient Removal of Cadmium Ions from Aqueous Solutions by Hydrous Ceric Oxide - A Radiotracer Study

The adsorption of cadmium ions on hydrous ceric oxide has been studied as a function of concentration (10~—10~ M), temperature (303-333 K) and pH (7.08-10.47) of adsorptive solution, applying radiotracer technique. The kinetics of adsorption was found to follow first order rate law with respect to adsorptive concentration and agrees well with classical Freundlich isotherm. The effect of temperature on equilibrium adsorption values has been utilized to evaluate the change in standard thermodynamic quantities (viz. ΔΗ°, AS° and AG). Pre-irradiation of adsorbent with neutrons and y-radiations from a 11.1 GBq (Ra—Be) neutron source having an integral neutron flux of 3.85 Χ10 neutrons/cm/sec and associated with a nominal y-dose of ca. 1.72 Gy/hour has practically no effect on the extent of adsorption of cadmium ions. The sorption process was found to be endothermic and irreversible in nature.

Radiotracer Technique in Adsorption Study Part XV. Removal Behaviour of Barium Titanate for Mercury Ions

Adsorption of Hg(II) ions on barium titanate have been investigated over a wide range of concentration (10 10 * M), temperature (303-333 K) and pH (3.2-10.4) of the adsorptive solution using a radiotracer technique. The uptake was found to increase with increasing concentration, temperature and pH of the adsorptive solution. Kinetics of the process follows a first order rate law and agrees well with the classical Freundlich isotherm for the entire range of adsorptive concentration. Removal appears to be ion-exchange in type and thermodynamically irreversible in nature.

Inorganic Particulates in Removal of Toxic Heavy Metal Ions. Efficient Removal of Cadmium Ions from Aqueous Solution by Hydrous Zirconium Oxide

Adsorption of cadmium ions on hydrous zirconium oxide (HZO) has been studied as a function of Cd(II) concentration, temperature and pH applying radiotracer technique. The uptake process was favoured at higher concentrations and temperature. The kinetics of the process follow first order rate law and obey the classical Freundlich isotherm over the entire ränge of the bulk concentration of Cd(II). The process was found to be ion exchange type and irreversible in nature. Effect of some cations and acid concentrations on the uptake of cadmium was also observed.

Radiotracer technique in adsorption study—XIII. Adsorption of barium and strontium ions on chromium(IV) oxide powder

Abstract The applicability of chromium(IV) oxide for efficient removal of barium and strontium ions from aqueous solutions by adsorption has been investigated. Lower concentrations of Ba 2+ , Sr 2+ solutions with higher pH and temperature were found to be favourable conditions for adsorption of Ba(II) and Sr(II) on chromium(IV) oxide. The kinetics of adsorption of Ba(II) and Sr(II) follows essentially a first-order rate law with bulk ion concentration and obeys the Freundlich isotherm in the entire range of metal ion concentration (10 −2 –10 −7 M). The uptake process was found to be endothermic and irreversible in nature. Equilibrium adsorption values at different temperatures have been utilized to evaluate change in standard thermodynamic quantities (viz ΔH 0 , ΔG 0 and ΔS 0 ). The adsorption of Ba(II) and Sr(II) ions were not significantly affected by the exposure of chromium(IV) oxide adsorbent to neutrons and γ-radiations from a (Raue5f8Be) neutron source having an integral neutron flux of 3.85 × 10 6 neutron/cm 2 /s and associated with nominal γ-dose of ca 172 rad/h.

Radiotracer technique in adsorption study—XI. Adsorption of barium and strontium ions on hydrous ceric oxide☆

Abstract Adsorption behavior of Ba and Sr ions on hydrous ceric oxide in aqueous solution has been studied as a function of concentration (10−2–10−7 M), temperature (303–333 K) and pH (7.24–11.42) of the adsorptive solution applying radiotracer technique. The kinetics of adsorption for both ions follows first-order rate law and agrees well with the classical Freundlich isotherm in the entire range of adsorptive concentration. The effect of temperature on the equilibrium adsorption values has been utilized to evaluate the change in standard thermodynamics quantities (viz. ΔH0, ΔG0 and ΔS0). Pre-irradiation of adsorbent with neutrons (3.85 × 106 n cm−2 s−1) and γ-radiations (ca 172 rad h−1) has practically no effect on the extent of adsorption for both the ions. The uptake process for both ions is found to be endothermic and irreversible in nature.

Radiotracer technique in adsorption study: Part XVII. Removal Behaviour of Alkali Metal (K- and Li-) Titanates for Cd(II)

Abstract Alkali metal (potassium and lithium) titanates were synthesized and employed for the efficient removal of Cd(II) ions from aqueous solutions using the radiotracer technique . The possible mechanism involved at the solid/solution interface was deduced with the help of various physico–chemical data, i.e. effect of adsorptive concentration temperature and pH. The effect of added cations and H + (HCl/H 2 SO 4 ) in the uptake process was also seen. The radiation stability of these materials in the adsorption process was assessed by employing a 11.1xa0GBq (Ra–Be) neutron source having an integral neutron flux of 3.85×10 6 xa0n·cm −2 xa0s −1 and associated with a nominal γ -dose of ca. 1.72xa0Gy/h.

Inorganic particulates in removal of toxic heavy metal ions: IV. Efficient removal of zinc ions from aqueous solution by hydrous zirconium oxide

Adsorption behavior of zinc ions on hydrous zirconium oxide (HZO) in aqueous solution has been studied as a function of concentration (10−2–10−8M), temperature (303–333 K) and pH 3–8 of adsorptive solution applying radiotracer technique. The kinetics of adsorption follows first order rate law and agrees well with the classical Freundlich isotherm in the entire range of adsorptive concentration. The removal was found to be increasing with pH of the adsorptive solution while it was suppressed in the presence of acid concentrations. The overall process is found to be endothermic and irreversible in nature.

INORGANIC PARTICULATES IN REMOVAL OF TOXIC HEAVY METAL IONS: RAPID AND EFFICIENT REMOVAL OF HG(II) AND CR(III) IONS FROM AQUEOUS SOLUTIONS BY SODIUM T ITANATE

Radiotracer technique has been used to study the removal of Hg(II) and Cr(ni) ions from aqueous solutions by synthesized and well characterized sodium titanate powder. Adsorptive concentration (10-^-10 moldm), pH (ca. 3.0-10.0) and temperature (303-333 K) were examined for assessing optimal conditions for removal of these ions. The uptake of Hg(II) and Cr(in) ions, which fitted well for Freundlich isotherm, increased with increase in the temperature and no significant desorption took place in the studied temperature ränge. The presence of some anions/cations affected the uptake of metal ions markedly. Increasing the H^ ion concentration (HCI/H2SO4) decreased the removal of these ions. Irradiation of sodium titanate by using a 11.1 GBq (Ra-Be) neutron source having a neutron flux density of 3.9 X 10 cm~^ s and associated with a y-dose rate of 1.7 Gy/h and also by using a Gamma cell (4.7 kGy/h) did not influence the extent of adsorption of Hg(II) and Cr(III) ions.

Copper(II) and Zinc(II) Chelates of Some Bisheterocycles as Fungicides

Abstract Cu(II) and Zn(II) complexes of 2-[[(5-substituted-1,3,4-oxadiazole-2-yl) thio]methyl]-1H-benzimidazole, 2-[[(5-substituted-1,3,4-thiadiazol-2-yl) thio]methyl] 1H- benzimidazole and 2-[[(5-substituted-4-amino-1,2,4-triazol-3-yl) thio]methyl] 1H-benzimidazole have been prepared and characterized by elemental analyses, IR, 1H and 13C NMR (of Zn(II) complexes only), UV/visible and ESR spectra along with magnetic studies. The complexes have also been screened for their antifungal activities aganist H. oryzae and R. solani.