Advanced Materials Research Vols. 726-731

Abstract: Porous suspended ceramsite (PSC) supported nanoscale zero valent iron (NZVI/PSC) were applied to the reductive removal of nitrate to investigate the effects. XRD, SEM and EDS analyses on NZVI/PSC revealed that PSC had loaded some nanoparticles, whose size was about 50 nm. Nitrate reduction rate of NZVI/PSC reached about 80% in 60 min, while the PSC unsupported nanozerovalent iron performed poorly with only 8% removal of the nitrate. Furthmore, during the reactions of NZVI/PSC and PSC with nitrate, for the NZVI/PSC, pH change was the greatest, while the reaction with PSC (this particles shows the lowest reactivity for nitrate reduction) resulted in the least pH change.

Abstract: Poly (vinylpyrrolidone)-anchored iridium nanoparticles (PVP-Ir) were prepared via the reduction of H₂IrCl₆·nH₂O in ethanol/water mixtures. The catalytic properties of the colloidal nanoparticles that dispersed on Al₂O₃ (PVP-Ir/Al₂O₃) were investigated in the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). The results indicated that the selectivity to p-CAN remained on the level of 100 % at complete conversion of p-CNB at lower temperature of 288 K. Moreover, the side reaction of hydrogenolysis of the carbon-halogen bond was completely inhibited in the absence of promoters and inhibitors. The great improvement on activity and selectivity of PVP-Ir/Al₂O₃ was attributed to the highly and homogeneously dispersion of the iridium nanoparticles on the support Al₂O₃ and the addition of appropriate amount of water in organic solvents

Abstract: Aluminum and iron copillared rectorite (Al/Fe-R) was prepared from sodium saturated rectorite (Na-R) by ultrasonic-assisted pillaring with hydroxyalumina and hydroxyiron polycations. The morphology, composite structure, pore properties and light response characteristics of composite material were observed with scanning electron microscopy (SEM), small angle X-ray Diffraction (XRD), nitrogen adsorption-desorption isotherm and UVvis diffuse reflectance spectrum. The fabricated material retained the layered structure with a slit-shaped pore between the layers of lamellar particles. The interlayer spacing d₀₀₁ was increased successfully from 2.23 nm up to 2.98 nm. The resultant product has a high BET specific surface area of 165 m² g^-1 and good visible light response. The Al/Fe-R shows the potential to become a good adsorbent and catalyst.

Abstract: A novel precursor, 6FAPB-PMDA type polyimide, was developed to prepare carbon membranes and carbon nanotube (CNT) composite carbon membranes. The thermal stability of precursors was characterized by TGA. The morphology of carbon membrane was observed by SEM. The microstructure was measured by XRD and nitrogen adsorption technique. Results have shown that 6FAPB-PMDA type polyimide is a promising precursor, and the introduction of CNT can obviously modify the thermal stability, as well as the carbon and porous structure of resultant carbon membranes.

Abstract: Humic acid adsorbent modified with metal ions was prepared by gel polymerization and named gel composite of metal ion and humic acid, which abbreviated GCMH to uptake fluoride from drinking water. The samples were measured by X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images. Fluoride adsorption onto the synthesized samples was investigated by batch adsorption method. In previous works, detailed studies were carried out to investigate the effect of contact time, adsorbent dose, initial solution pH, temperatures and co-existing anions. The maximum fluoride removal was obtained at pH7. Presence of HCO3− adversely affected the adsorption of fluoride. The optimum absorption conditions were at the dose of 10g/L, temperature of water of 55°Cand contact time of 6hs.

Abstract: A novel surface ion-imprinted polymer (S-IIP) has been synthesized by surface ion-imprinting concept in the presence of sodium trititanate whisker, Sr(II), chitosan and γ-Glycidoxypropyl trimethoxysilane (KH-560) for selective solid-phase extraction (SPE) of trace Co(II) from aqueous solutions. Characterizations of S-IIP were achieved by FT-IR spectra, SEM and surface area measurement. Results showed that the adsorption of cobalt(II) onto S-IIP follows pseudo-second order kinetics and could be fitted by the Langmuir isotherm with the maximum adsorption capacity Q being 8.27 mg×g^-1 at 25°C. Thermodynamic parameters including DHº, DGº and DSº were calculated and it is indicated that Co(II) adsorption on S-IIP is exothermic, spontaneous and physical adsorption reaction. Moreover, according to the dimensionless separation factor R_L (R_L<1) it indicates that it’s a highly favourable adsorption. Finally, the detection limit (3s) of 5.6 ng·mL^-1 with the relative standard deviation (RSD) for 1.0 μg×mL^-1 cobalt(II) of 1.86% (n=10) were obtained.

Abstract: Uniform highly ordered mesoporous silica nanofiber membrane was successfully prepared onto copper mesh via coaxial electrospinning combining with the solvent evaporation and extraction induced surfactant assembly process. After a high temperature treatment and amination, it was employed to remove reactive yellow 2 (RY2) in wastewater showing remarkable adsorption capacity. The maximum adsorption capacity can reach up to 371.7 mg/g. The structural properties of synthesized mesoporous silica were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectrum (FTIR). And the adsorption behavior of prepared material was analyzed through three kinds of isotherm models.

Abstract: In order to explore the optimal method to prepare high performance activated carbon precursors from medium temperature coal tar pitch, orthogonal tests are adopted to study the effects of oxygen-blowing time in the pretreatment process as well as carbonization temperature and carbonization time in activation and carbonization processes on the adsorption capacities of activated carbon. Moreover, the effects of additives (coke powder and anionic surfactant) on the adsorption capacities of activated carbon are examined. The results show that the factors affecting the adsorption capacities of pitch-based activated carbon, in order of importance, are carbonization temperature, oxygen-blowing time, carbonization time and additives. The optimal conditions for preparation of activated carbon precursor from medium temperature pitch are: 4h for oxygen-blowing time, 400°C for carbonization temperature, 60 minutes for carbonization time and no additives. The iodine absorption capacity of the prepared activated carbon precursor which is activated for 100 min at 800°C is 1739mg/g.

Abstract: The biodegradable hydroxy-functionalized poly(oligo(ethylene oxide) monomethyl ether methacrylate) (HO-POEOMA) polymer is synthesized by inverse miniemulsion atom transfer radical polymerization (ATRP). The chain structure and component of such polymer is characterized by spectroscopic studies (¹HNMR, IR and GPC).

Abstract: A series of mesoporous TiO2 supports were synthesized by the sol-gel template method by using different surfactant and Au/TiO2 catalysts were prepared by the solution reduction method. The catalytic oxidation of CO was taken as the probe reaction for comparing the catalyst activity. Wide-angle XRD patterns and N2 adsorption–desorption isotherms revealed that the TiO2 with crystallized anatase and mesoporous structure can be synthesized after an optimized sol-gel template method. The results indicated that the pore size of TiO2 plays a key role in the catalyst activity. Among them the activity of Au/TiO2-F1 catalyst synthesized by using the F127 surfactant demonstrated superior activity to other catalysts. CO could be converted at 70 °C.