Dongbei Wu

Adsorption of lanthanum (III) from aqueous solution using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester-grafted magnetic silica nanocomposites

In view of increasing attention of magnetic materials in the field of separation science and technology, we provide an effective route for fabrication of a new magnetic material with high adsorption capacity and selectivity toward metal ions, excellent acid resistance property and long service life. Silica was firstly coated on the magnetic particles, and then silane-coupling agent (3-chloropropyltryethosysilane) was used for grating 2-ethylhexyl phosphonic acid mono-2-ethylhexyl (P507), an organophosphorous acid extractant, on the surface of magnetic silica nanocomposite. The amount of P507 anchored on the particle was estimated to be 0.43 mmol/g. The P507-grafted magnetic silica nanocomposite was stable over pH range of 0-14. The maximum adsorption capacity of La (III) was 55.9 mg/g at the optimized pH 5.5. The adsorption of La (III) on our nanocomposites was found to follow the second order kinetics equation and fit Langmuir isotherm model well. The PO functional groups took an important role in the coordination and adsorption mechanism, which was confirmed by FTIR and XPS techniques. After 10 adsorption/desorption cycles, no obvious decrease in adsorption capacity or obvious loss in saturation magnetization were observed.

Selective adsorption of molybdenum(VI) from Mo-Re bearing effluent by chemically modified astringent persimmon.

Astringent persimmon was chemically cross-linked by formaldehyde to obtain a novel kind of adsorption gel, which was named as APF gel. The adsorption behaviors of Mo(VI) and Re(VII) along with other coexisting metals onto the APF gel were studied in the present paper. The APF gel was found to be effective for the adsorption of Mo(VI) while the gel is almost completely inert toward rhenium and calcium over the whole hydrochloric acid concentration region. The APF gel has a low affinity for iron, copper, lead, nickel, manganese and zinc ions when the concentration of HCl is higher than 1 mol/L. The gel exhibited selectivity only for Mo(VI) with a remarkably high adsorption capacity 1.05 mol/kg, and the adsorption behavior obeys the Langmuir model. According to the thermodynamic and kinetic studies, the endothermic adsorption process followed pseudo-second order kinetics. Also, its excellent adsorption characteristics for Mo(VI) were confirmed by the adsorption and elution tests using a column packed with the APF gel. The result provides a new approach for the recovery of Mo(VI) from a industrial waste effluent.

Gum Arabic: A promising candidate for the construction of physical hydrogels exhibiting highly stretchable, self-healing and tensility reinforcing performances

The preparation of tough and healable hydrogels in one step remains a big challenge throughout the field of hydrogel methodology. Herein, we fabricated a series of Poly(N,N-dimethyl acrylamide)-TiO2-gum arabic (PDMAA-TiO2-GA) hybrid hydrogels by simply introducing nanoparticles TiO2 and vinyl-modified gum arabic (GMAGA) into polymer networks. Without complicate molecular design and post-treating process, the hydrogel molding process was simple and effective. The hydrogel exhibited highly stretchable, self-healing and tensility reinforcing performances with the optimized compositions of 30% DMAA, 0.6% GMAGA and 0.13% TiO2. The maximum elongation of the hydrogel after self-healing recover could reach nearly 700% after only 20min healing time. The hydrogel could ensure 20 times continuous compressive or tensile tests without obvious deformation. Amazing was the significantly enhanced tensile modulus from 5kPa to 40kPa after 20 stretch-release cycles. The facile preparation and fascinating tensility reinforcing performance benefit the potential application of the carbohydrate GA in hydrogels.

Removal of europium on GMZ bentonite corroded by young cement water at different temperatures

After construction of the high-level radioactive waste repository, the bentonite undergoes corrosion of the alkaline solution produced by cement degradation. Young cement water-YCW was employed to carry out the corrosion experiments on compacted GMZ bentonite specimens. Then the removal of europium (Eu(III)) onto corroded GMZ bentonite was studied by batch experiments. The results show the YCW corroded GMZ bentonite is still an effective adsorbent. The adsorption reaction of Eu(III) on corroded GMZ bentonite is endothermic. It can be described by Langmuir isotherm model well. The bentonite corroded at higher temperature shows more stable sorption property.

Thermal Conductivity of Compacted GO-GMZ Bentonite Used as Buffer Material for a High-Level Radioactive Waste Repository

In China, Gaomiaozi (GMZ) bentonite serves as a feasible buffer material in the high-level radioactive waste (HLW) repository, while its thermal conductivity is seen as a crucial parameter for the safety running of the HLW disposal. Due to the tremendous amount of heat released by such waste, the thermal conductivity of the buffer material is a crucial parameter for the safety running of the high-level radioactive waste disposal. For the purpose of improving its thermal conductivity, this research used the graphene oxide (GO) to modify the pure bentonite and then the nanocarbon-based bentonite (GO-GMZ) was obtained chemically. The thermal conductivity of this modified soil has been measured and investigated under various conditions in this study: the GO content, dry density, and water content. Researches confirm that the thermal conductivity of the modified bentonite is codetermined by the three conditions mentioned above, namely, the value of GO content, dry density, and water content. Besides, the study proposes an improved geometric mean model based on the special condition to predict the thermal conductivity of the compacted specimen; moreover, the calculated values are also compared with the experimental data.