Magnetic nanoparticles (MNPs) modified simultaneously with amorphous Fe and Mn oxides (Mag-Fe-Mn) were synthesized to remove arsenite [As(III)] from water. Mag-Fe-Mn particles were fabricated through heterogeneous nucleation technique by employing the maghemite as the magnetic core and Fe Mn binary oxide (FMBO) as the coating materials. Powder X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy were utilized to characterize the hybrid material. With a saturation magnetization of 23.2 emu/g, Mag-Fe-Mn particles with size of 20 -50 nm could be easily separated from solutions with a simple magnetic process in short time (within 5 min). At pH 7.0, 200 mu g/L of As(III) could be easily decreased to below 10 mu g/L by Mag-Fe-Mn particles (0.1 g/L) within 20 min. As(III) could be effectively removed by Mag-Fe-Mn particles at initial pH range from 4 to 8 and the residual As was completely oxidized to less toxic arsenate [As(V)]. The co-occurring redox reactions between Mn oxide and As(III) was confirmed by XPS analysis. Chloride, sulfate, bicarbonate, and nitrate at common concentration range had negligible influence on As(III) removal, whereas, silicate and phosphate reduced the As(III) removal by competing with arsenic species for adsorption sites. As(M) removal was not obviously affected by natural organic matter (up to 8 mg/L as TOC). Mag-Fe-Mn could be regenerated with ternary solution of NaOH, NaCl, and NaClO. Throughout five consecutive cycles, the adsorption and desorption efficiencies maintained above 98% and 87%, respectively. Mag-Fe-Mn had a larger adsorption capacity for As(III) (47.76 mg/g) and could remove trace As(III) more thoroughly than MNPs modified solely with either Fe or Mn oxide due to the synergistic effect of the coating Fe and Mn oxides. This research extended the potential applicability of FMBO to a great extent and provided a convenient approach to efficiently remove trace As(III) from water. (C) 2013 Elsevier Ltd. All rights reserved.
A micromechanics-based elastoplastic constitutive model for porous materials is proposed. With an assumption of modified three-dimensional Ramberg-Osgood equation for the compressible matrix material, the variational principle based on a linear comparison composite is applied to study the effective mechanical properties of the porous materials. Analytical expressions of elastoplastic constitutive relations are derived by means of micromechanics principles and homogenization procedures. It is demonstrated that the derived expressions do not involve any additional material constants to be fitted with experimental data. The model can be useful in the prediction of mechanical properties of elastoplastic porous solids.
An effective method was developed to prepare triphenyleno[1,2,3,4-ghi]perylenediimide derivatives, via ICl-induced annulation, dehalogenation, followed by photocyclization. A perylenediimide (PDI) dimer featuring a terphenyl bisethynylene linker was thereby transformed into a benzo[k]tetraphene fused with two benzoperylenediimides. These PDI derivatives exhibited electron mobility up to 0.079 cm(2) V-1 s(-1) in solution-processed thin film transistors.
An experimental investigation is performed on the interaction of intense femtosecond laser pulses at the intensity of 6 × 1017 W/cm2 (55 fs, 160 mJ at 800 nm) with ethane cluster (C2H6) N jets prepared under the backing pressure of 30 bars at room temperature (298 K). The experiment results indicate the generation of energetic protons, whose average and maximum kinetic energies are 12.2 and 138.1 keV, respectively, by Coulomb explosion of (C2H6) N clusters. (C2H6) N clusters of 5 nm in radius are generated in the experiment, which are 1.7 times larger than that of (CH4) N clusters prepared in the same conditions. Empirical estimation suggests that (C2H6) N clusters with radius of about 9.6 nm can be prepared at 80-bars backing pressure at 308 K. While (C2H6) N clusters of so large size are irradiated by sufficiently intense laser pulses, the average energy of protons will be increased up to 50 keV. It is inferred that such large-size deuterated ethane clusters (C2D6) N will favor more efficient neutron generation due to the significant increase of the D-D nuclear reaction cross section in laser-driven cluster nuclear fusion.