Effect of ammonium, carbonate and fluoride concentration on the uranium recovery by resins

2005 ◽  
Vol 93 (4) ◽  
Author(s):  
Ana C. Q. Ladeira ◽  
Carlos A. Morais
Keyword(s):  
Exchange Process ◽  
Fluoride Concentration ◽  
Alkaline Solutions ◽  
High Concentration ◽  
Solution Ph ◽  
Uranium Recovery ◽  
Strong Base ◽  
Base Resin ◽  
Wide Ph Range ◽  
Ph Range

SummaryUranium in solution can be precipitated over a wide pH range, from acidity and alkalinity, depending upon the solution and the precipitant used. The precipitate is generally filtered and the solution resultant contains uranium that should be recovered. This work is aimed at the selection of an appropriate resin for uranium recovery from alkaline solutions in the presence of ammonia, carbonate and fluoride. The ability of uranium extraction of 3 types of polymeric strong base resin was assessed. Laboratory solutions were prepared to determine the influence of the ions like ammonia, carbonate and fluoride on the uranium recovery by resins. The uranium concentration was 100 mg/L and the solution pH ranged from 9.2 to 10.4. The results, obtained by batch experiments, showed that excess of carbonate and fluoride completely inhibit uranium uptake in the pH range studied. Even low concentrations of fluoride and carbonate decrease uranium adsorption by resins. The optimum concentration was below 2.5 g/L (0.04 mol/L) and 5.0 g/L (0.26 mol/L) for carbonate and fluoride, respectively. The presence of high concentration of ammonia up to 20 g/L (1.20 mol/L) did not inhibit the uranium exchange process. Among the three types of resins studied IRA 910U was the most promising adsorbent for uranium at the conditions employed in this work.

scholarly journals Enhanced fluoride removal from drinking water in wide pH range using La/Fe/Al oxides loaded rice straw biochar

2021 ◽  
Author(s):  
Nan Zhou ◽  
Xiangxin Guo ◽  
Changqing Ye ◽  
Ling Yan ◽  
Weishi Gu ◽  
...  
Keyword(s):  
Drinking Water ◽  
Rice Straw ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
Solution Ph ◽  
Adsorption Sites ◽  
Wide Ph Range ◽  
Rice Straw Biochar ◽  
Ph Range

Abstract A novel and highly efficient adsorbent was prepared by loading La/Fe/Al oxides onto rice straw biochar (RSBC) and was tested for the ability to remove fluoride from drinking water. Characterized by SEM, XRD, Zetapotential and FTIR, it was found that the ternary metal oxides were successfully loaded on the surface of biochar in amorphous form, resulting in the formation of hydroxyl active adsorption sites and positive charges, which played a synergistic role in fluoride removal. Through batch adsorption tests, key factors including contact time, initial fluoride concentration, initial pH and co-existing anions effects were investigated. Results showed that the tri-metallic modified biochar (La/Fe/Al-RSBC) had excellent fluoride removal performance with an adsorption capacity of 111.11 mg/g. Solution pH had little impacts on the removal of fluoride, the adsorbent retained excellent fluoride removal capacity in a wide pH range of 3.0–11.0. The co-existing anions had almost no effect on the fluoride removal by La/Fe/Al-RSBC. In addition, La/Fe/Al-RSBC could be regenerated and reused. Electrostatic adsorption and ion exchange were responsible for this adsorption behavior. These findings suggested the broad application prospect of a prepared biochar adsorbent based on rare earth and aluminum impregnation for the fluoride removal from drinking water.

scholarly journals Antioxidant properties, quantification and stability of betalains from pitaya (Hylocereus undatus) peel

2014 ◽  
Vol 45 (2) ◽  
pp. 323-328 ◽  
Author(s):  
Fernanda Robert de Mello ◽  
Claudia Bernardo ◽  
Caroline Odebrecht Dias ◽  
Luciano Gonzaga ◽  
Edna Regina Amante ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Antioxidant Properties ◽  
Raw Material ◽  
High Concentration ◽  
Natural Colorant ◽  
Wide Ph Range ◽  
Hylocereus Undatus ◽  
Ph Range ◽  
Promising Source

Pitaya peel can be used as a raw material for betalains extraction. The aim of this research was to quantify phenolic compounds, antioxidant activity and betalains on pitaya peel. Furthermore, evaluate the betalains stability against various pH conditions and exposure time of heating. The results showed that pitaya peel contains phenolic compounds and presented antioxidant activity. Moreover it showed high concentration of betalains (101.04mg equivalent to betanin. 100g-1) which were stable over a wide pH range (3.2 - 7.0) and were resistant to heating (100oC) up to 10 minutes at pH range from 3.7 to 5.5. Therefore, pitaya peel is a promising source of betalains which can be applied as a natural colorant for food.

Structural changes of flavylium salts. IV. Polarographic and spectrometric examination of pelargonidin chloride

1968 ◽  
Vol 21 (1) ◽  
pp. 221 ◽  
Author(s):  
KA Harper
Keyword(s):  
Ring Opening ◽  
Structural Changes ◽  
Equilibrium Mixture ◽  
Ring Cleavage ◽  
Alkaline Solutions ◽  
Similar Reaction ◽  
Anodic Wave ◽  
Wide Ph Range ◽  
Phenolic Group ◽  
Ph Range

Pelargonidin chloride has been examined polarographically and spectrometrically in aqueous methanol over a wide pH range and the molecular changes determined. In strongly acid solutions the flavylium ion is stable, but between pH3 and pH8 ring opening to the α-diketone occurs, the process involving the pseudo-base and its 3-keto tautomer. The pseudo-base is present in the equilibrium mixture from pH3 to pH12 in amount varying with the pH. The anhydrobase, detected in the equilibrium mixture at pH6, is stable above pH7, becoming ionized as the pH is raised. Unlike the anhydrobase of the simpler flavylium salts, the anhydrobase of pelargonidin chloride does not undergo ring cleavage in strong alkali under the conditions of these experiments. Ionization of the phenolic group at C5 was indicated by a, small anodic wave in the polarograms above pH9.5, due to mercuration at C6. A similar reaction, analogous to the known catalytic mercuration of ketones, was observed for phloroglucinol and resorcinol in alkaline solutions.

scholarly journals EPR study of the production of oh radicals in aqueous solutions of uranium irradiated by ultraviolet light

2009 ◽  
Vol 74 (6) ◽  
pp. 651-661 ◽  
Author(s):  
Marko Dakovic ◽  
Milos Mojovic ◽  
Goran Bacic
Keyword(s):  
Aqueous Solutions ◽  
Hydroxyl Radicals ◽  
Fluorescence Decay ◽  
Uranyl Acetate ◽  
Oh Radicals ◽  
Solution Ph ◽  
Trapping Method ◽  
Wide Ph Range ◽  
Ph Range ◽  
Epr Spin Trapping

The aim of the study was to establish whether hydroxyl radicals (?OH) were produced in UV-irradiated aqueous solutions of uranyl salts. The production of ?OH was studied in uranyl acetate and nitrate solutions by an EPR spin trap method over a wide pH range, with variation of the uranium concentrations. The production of ?OH in uranyl solutions irradiated with UV was unequivocally demonstrated for the first time using the EPR spin-trapping method. The production of ?OH can be connected to speciation of uranium species in aqueous solutions, showing a complex dependence on the solution pH. When compared with the results of radiative de-excitation of excited uranyl (+22*UO ) by the quenching of its fluorescence, the present results indicate that the generation of hydroxyl radicals plays a major role in the fluorescence decay of + 22 *UO . The role of the presence of carbonates and counter ions pertinent to environmental conditions in biological systems on the production of hydroxyl radicals was also assessed in an attempt to reveal the mechanism of +22*UO de-excitation. Various mechanisms, including ?OH production, are inferred but the main point is that the generation of ?OH in uranium containing solutions must be considered when assessing uranium toxicity.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

High degradation efficiency of sulfamethazine with the dual-reaction-center Fe-Mn-SiO2 Fenton-like nanocatalyst in a wide pH range

2021 ◽  
Author(s):  
Manoj Kumar Panjwani ◽  
Qing Wang ◽  
Yueming Ma ◽  
Yuxuan Lin ◽  
Feng Xiao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Reaction Center ◽  
Degradation Efficiency ◽  
Heterogeneous Fenton ◽  
Wide Ph Range ◽  
Ph Range

The development of a heterogeneous Fenton-like catalyst, possessing high degradation efficiency in a wide pH range, is crucial for wastewater treatment. The Fe-Mn-SiO2 catalyst was designed, and prepared by a...

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