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Tetraphenyldithiodiphosphonate is synthesized by polymerization precipitation. The P = S bond of the material has strong polarity, which is conducive to improving the electron mobility of the complex and inhibiting the accumulation between molecules. The synthesized tetraphenyldithiodiphosphonate is characterized by FT-IR, SEM, XPS and XRD. In addition, the pseudo-second-order kinetic model is used to simulate the experimental data well, and the adsorption process conforms to the Langmuir isotherm model. Thermodynamic studies of adsorption have shown that the adsorption process is essentially a spontaneous endothermic process. At room temperature, tetraphenyldithiodiphosphonate demonstrates a maximum adsorption capacity for uranium(VI) reaching 398.8 mg g−1. [ABSTRACT FROM AUTHOR]

In this study, amino modified mesoporous silica (HMS-TEEPA-TEA) was used for the first time to remove uranium (VI) from aqueous solution. The synthesized HMS-TEEPA-TEA was characterized by SEM, EDS, FTIR, BET and XPS techniques. The present work attempted to optimize and compare the adsorption process parameters like pH, adsorbate concentration, and adsorbent dose using Box-Behnken designs of response surface methodology. The adsorption amount and removal rate reached 337.26 mg/g and 99.57%, respectively. Model P> F < 0.0001 in this experiment (generally P > F < 0.05 is considered significant), indicating that the model is extremely significant and can be considered as highly referable for its predicted response values. The fit of the data to the Langmuir isotherm and the proposed secondary kinetics indicates that the adsorption process is monolayer and chemical in nature. The effect of copper on HMS-TEEPA-TEA adsorption is more complex than other background ions. The removal of uranium (VI) by HMS-TEEPA-TEA remained above 80% for four consecutive experiments with repeated adsorbent use. The results indicate that HMS-TEEPA-TEA is an effective adsorbent for the removal of uranium (VI) from aqueous solutions with the advantages of low cost, high availability and easy production. [ABSTRACT FROM AUTHOR]

In this work, a new material containing chitosan(CS)-hexachlorocyclotriphosphazene (HP) composite was synthesized with polyphosphoric acid as the cross-linking agent for the effective removal of uranium(VI) from aqueous solution. The prepared material was characterized by FTIR, EDS, SEM, BET and XPS. According to batch experiments, its adsorption equilibrium (Qe = 398.8 mg g−1) was reached within 50 min at pH 6.0. The adsorption process could be well fitted to the pseudo-second-order model and the Langmuir model. The thermodynamic analysis indicated that the adsorption was an exothermic and spontaneous process. Furthermore, the CS-HP has superior absorption reusability. This study proved that CS-HP could be considered as the highly efficient and sustainable material for removal of uranium(VI) from aqueous solution. [ABSTRACT FROM AUTHOR]

Immobilized Saccharomyces cerevisiae (ISC) was prepared by the sodium alginate-gelatin embedding method after dry cells had been cross-linked by formaldehyde. Adsorption of uranium(VI) by incompletely and completely dry ISC was studied. The results indicated that incompletely dry ISC had greater adsorption capacity for U(VI), with physical adsorption being the primary mechanism, whereas completely dry ISC exhibited much greater rigidity and much smaller volume. Therefore, initial absorption of U(VI) by incompletely dry ISC followed by heating could be compared with glass solidification for disposal of radioactive waste. The influence of solution pH, temperature, and contact time on U(VI) absorption was also studied, with pH being found to be the main influencing factor. The adsorption mechanism of completely dry ISC was explored by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, indicating that the main adsorption mechanism is chemical adsorption. [ABSTRACT FROM AUTHOR]