Sun Guoxin

Extraction of U(VI) with unsymmetrical N-methyl-N-decylalkylamide in toluene

A number of structurallyrelated new unsymmetrical monoamides with different substituting groups, N-methylN-decyloctylamide (MDOA), N-methyl-N-decyldecanamide (MDDA), and N-methyl-N-decyldodecanamide (MDDOA), were synthesized. The extraction of U(VI) from nitric acid medium by the synthesized monoamides diluted with toluene was investigated. The effect of nitric acid concentration, sodium nitrate concentration, extractant concentration and temperature on the distribution ratio was studied. The stoichiometry of the main extracted species confirms to UO 2(NO3)2 ·2A (A, amidic extractant). The values of the thermodynamic parameters were determined and the extraction reactions were found exothermic. The IR spectral study was also made of the extracted species.

Mineral weathering and element cycling in soil-microorganism-plant system

Soil is an essential part of the critical zone, and soil-microbe-plant system serves as a key link among lithosphere, biosphere, atmosphere and hydrosphere. As one of the habitats with the richest biodiversity, soil plays a critical role in element biogeochemistry on the earth surface (weathered crust). Here we review the soil biological processes that are relevant to mineral weathering, element cycling, and transformation, with an emphasis on rock weathering mediated by soil microbes, plant root and the rhizosphere.

INTERFACIAL ACTIVITY OF HDEHP AND KINETICS OF NICKEL EXTRACTION IN VARIOUS DILUENTS

ABSTRACT The interfacial behavior of HDEHP at various diluents/0.05M (H2,Na2)SO4 interfaces was examined using the Drop Volume Method. Different adsorption isotherms such as the Gibbs and Szyszkowski were found as fits well to the experimental interfacial tension isotherms. The values of surface excess at saturated interface,calculated according to them by using the concentration of individual species (e.g. organic monomeric species),increase in the order: MIBK<chloroform <benzene∼toluene∼xylene<CCl4 <n-hexane∼n-heptane The interfacial activity data were used to discuss the mechanism and kinetics of nickel extraction. It was shown that the interfacial mechanism is very probable and the extraction limiting step is the reaction between HDEHP molecules present near the interface and the intermediate 1:2 complex just as following Ni(H2O) 4A2(int,0) +2H2A2(int,0) =Ni(H2O) 2A2˙2H2A2(int,0) +2H2O(int,0) The investigation of the influence of diluent on the extraction rate supports the mechanism suggested.

SOLVENT EXTRACTION OF URANIUM (VI) BY N-OCTANOYLPYRROLIDINE IN TOLUENE

The extraction of uranium (VI) from nitric acid by N-octanoylpyrrolidine (OPOD) in toluene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures. The mechanism of extraction is discussed in the light of the obtained results.

Phenyl-N,N-dibutylcarbamoylmethyl sulfoxide as a new bifunctional extractant for extraction of uranium(VI) in toluene

A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium (VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO3). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species.

Synthesis and Characterization of Th(IV) and U(VI) Complexes with O-Vanillin-P-Phenylenediamine

Two new solid complexes, [ThL(NO3)2](NO3)2, [UO2L(NO3)]NO3 (L=o-vanillin-p-phenylenediamine) have been synthesized and characterized by elemental analyses, DTA-TG, IR spectra, UV spectra and molar conductance. Possible structures of the two complexes are proposed.

EFFECT OF DILUENT ON THE EXTRACTION OF URANIUM(VI) USING N, N-DIBUTYLDODECANAMIDE

A study has been made of the extraction of uranium(VI) from nitric acid solutions with Ν,Ν-dibutyldodecanamide (DBDOA) in a series of diluents. The dependence of extraction distribution on the concentration of aqueous nitric acid and DBDOA and also the temperature has been investigated. The experimental results showed that the extraction efficiency of DBDOA for uranium(VI) increases in the order: chloroform, n-octane, CCL,, 1,2-dichloroethane, c-hexane, 1,2,4-trimethylbenzene (TMB), xylene and benzene. It can not be interpreted only on the basis of polarity of the diluents. The interaction between extradant or extracted species and diluent is discussed.

Extraction Mechanism of Uranium(VI) with Di(1-Methylheptyl)Phosphoric Acid

The extraction of U(VI) from nitric acid solutions with di-(1-methylheptyl) phosphoric acid has been investigated. The dependence on nitric acid concentration, DMHPA concentration and temperature has been considered and the infra-red spectra of extracted species and extractant were recorded. The mechanism of extraction is discussed in the light of the results obtained.

Extraction of uranium(VI) by N-octanoylpiperidine in toluene

The extraction of uranium(VI) from nitric acid by N-octanoylpiperidine (OPPD) in toluene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures. The mechanism of extraction is discussed in the light of the results obtained. The extracted species have also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated.