Ligia Stoica

Decontamination of solutions containing radioactive substances by dissolved air flotation

Residual solutions contaminated with radioactive species require special treatment methods as the low concentrations of contaminants which may have important effects on the environment do not allow the direct use of classical methods. The paper reports the results of studies to separate 226Ra(II) (0.73 Bq 1−1 concentration) by coprecipitation as Ba(Ra)SO4, followed by dissolved air flotation. The selection of the collector (by σ and ζ determinations), optimum pH, concentration of the reactants, maturation time have been studied.

Kinetics of Cu2+ separation by flotation

Precipitate flotation is one of the most efficient and economic separation methods that has been widely applied in the last few years for ion-molecular and colloidal species, both representing pollutant and useful substances. The separation of Cuaq 2+ species from diluted aqueous systems is often studied for environment protection and for the recovery of copper. A systematical study of the whole process has to consider the dynamics of the process in order to optimize it. This paper represents a study concerning the kinetics of Cuaq 2+ ions separation by precipitate flotation using alkylamine type (laurylamine) and alkylammonium salt (lauryltrimethylammonium chloride) as cationic collectors and alkylsulphate and alkylcarboxilic type(sodium laurylsulphate and sodium oleate) as anionic collectors. The experimental data have been used in order to verify the classical first order model and three other first-order models, respectively, adjusted to the classical model. The experimental data have been analyzed with the PEAKFIT program. The results of the study sustain—by interpretation of the fitting parameters (the correlation coefficient, r, and the curve fit standard error, e)—a first-order kinetics for the separation process of Cu(II) hydroxide species by precipitate-flotation method. Among the studied kinetic models, the classical first-order model and the first-order reversible model is well fitting the experimental data, and the fully mixed reactor model describes, with acceptable errors, the Cuaq 2+ ions separation process by flotation.

Cu(II) Recovery from Aqueous Systems by Flotation

Abstract Ionmolecular and colloidal inorganic particles representing both pollutants and sources of useful substances require the separation from aqueous systems by modern techniques that also permit their removal and recovery. Ion flotation and precipitate flotation are considered as separation methods with wide application, especially for the small concentration ranges of noxious components, indicating high environmental and economical performances. The present paper presents the results of a research study concerning Cu(II) recovery from aqueous model systems by the precipitate flotation method, dissolved air flotation (DAF), with an anionic-type collector C18H33O2Na—sodium oleate (NaOL). The separation mechanism by the collector–Cu(II) interaction at optimum conditions was studied. A comparison of chemical analysis results with electronic and vibration spectra and thermal analysis for isolated species was also made. The results of the experimental data plead for the Cu(II) recovery separation from aqueous systems and its recovery as oxide after thermal decomposition of the species contained in the foam.

As(V) Recovering‐Separation from Aqueous Systems by DAF Technique

Abstract As(V) oxyanions removal from aqueous systems by dissolved air flotation (DAF) using Fe2O3 · xH2O as solid support and sodium laurate as anionic surfactant was investigated. The influencing factors of the process: pH, support, surfactant, and As(V) concentrations, the presence of flocculant and foreign ions, conditioning time and dissolved air pressure were discussed, as they may affect in a great extent the separation efficiency. The systematic study aims to establish the optimum operating parameters of the process, to investigate the equilibrium and mechanism of separation.

DECONTAMINATION OF THE URANIUM PROCESSING EFFLUENTS CONTAINING 226Ra(II)

The aqueous systems arising from the radioactive ores processing or from uranium mine, generally, require the application of purifying, and specially, of decontamination methods, according with the imposed limits of concentrations, recommended by International Standards. In this context, the paper reports on the results of our investigations regarding the 226Ra(II) removal, by applying adsorption on active carbon and coprecipitation-flotation (DAD).