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The phosphinimide materials described in this paper were synthesized by polymerization precipitation. The properties of complexes coordinated with metal ions can be used as adsorbents for the adsorption of radioactive elements by using ligands such as imide and phosphorus groups. Then, the synthetic phosphinimide was characterized in detail by FT-IR, SEM, EDS and XPS, and its morphology and structural changes were studied. In addition, the effects of the material on the removal of uranium(VI) from aqueous solutions at different pH, sorbent doses, contact times, initial concentrations, and temperatures were studied. The experimental data shows that the adsorption process can fit the pseudo-second-order kinetic model well, which is in line with the Langmuir isotherm model. The thermodynamic study of adsorption shows that the adsorption process is a spontaneous endothermic process. In addition, at a temperature of 303.15 K and pH = 6, the maximum adsorption of uranium(VI) by phosphinimide in 25 min can reach 234.6 mg g−1, and a removal rate of 97.75%. [ABSTRACT FROM AUTHOR]

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 study, Polyethyleneimine modified magnetic chitosan (MCS-PEI) was synthesized by grafting polyethyleneimine onto chitosan and adding magnetic Fe3O4 with sodium polyphosphate as crosslinking agent. The structure of the prepared material was characterized by FT-IR, SEM, EDS, XRD and XPS, which showed MCS-PEI was successfully synthesized. After a series of single factor experiments, the adsorption data fitted well with the Langmuir model (R2 = 0.99), being the maximum adsorption capacity equal 181.8 mg g−1. The pseudo-second-order model (R2 = 0.997) and Dubinin-Radushkevich model (R2 = 0.9598) indicated that the adsorption process was chemical adsorption. And thermodynamic studies showed that the adsorption was spontaneous and exothermic. The adsorption rate decreased by no more than 4% after the four adsorption–desorption experiments. This work illustrates that MCS-PEI is an environmental friendly, efficient and low-cost adsorbent. [ABSTRACT FROM AUTHOR]

With the continuous development of the nuclear industry, the amount of uranium containing wastewater discharged from the production process is increasing, which poses a great threat to the environment and human health. Therefore, it is an urgent task to find safe, environmentally friendly and efficient water treatment agents. Based on its unique molecular structure, chitosan can chemically react with anion system to adsorb pollutants, which has attracted the attention of scholars in the field of water treatment. However, the poor mechanical and adsorption properties of chitosan and the difficulty of recovery limit its development. To overcome the above shortcomings, chitosan is usually modified. In this paper, several modification methods of chitosan, including blending, crosslinking, grafting, ion imprinting and magnetization modification, are systematically described, and the advantages and disadvantages of different modification methods are analyzed. The application of modified chitosan adsorbent in uranium(VI) containing wastewater treatment is also introduced. Finally, the development trend of chitosan adsorbent in wastewater treatment is prospected. [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]

Poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) crosslinked microspheres with active amino groups on the surface were prepared by one-step precipitation polymerization method. The as-prepared material were characterized by means of FTIR, XPS, XRD, EDS and SEM. The effects of pH, time of contact, dosage, initial concentration and temperature on the adsorption of uranium(VI) by the crosslinked microspheres were studied, and the adsorption mechanism was elucidated. Under the optimized adsorption conditions, the adsorption removal efficiency reached 97.03%. The experimental results fit the Langmuir isotherm model and adsorption processes comply with the pseudo-second-order kinetic model. Thermodynamic data revealed that the adsorption behavior of uranium(VI) on the microspheres was spontaneous and exothermic. [ABSTRACT FROM AUTHOR]

Poly(cyclotriphosphazene-co-phloroglucinol) (PCPP) microspheres, a new solid phase extraction for extracting uranium(VI), synthesized via one-pot precipitation copolymerization. The PCPP microspheres were characterized by FT-IR, SEM/EDS, zeta potential and N2 adsorption/desorption isotherms. Through the extraction experiment to evaluate the extraction behavior of the PCPP microspheres for uranium(VI). The extractant can achieve the optimal effect under the conditions of contact time with 60 min, pH = 3.5, initial concentration 100 mg L−1 and extractant dosage 0.70 g L−1. The extraction behavior obeyed with the pseudo second-order model and Langmuir isotherm model. [ABSTRACT FROM AUTHOR]