Advanced Materials Research Vols. 726-731

Abstract: A green and sustainable route for preparation of hydrochars from cornstalk by hydrothermal carbonization (200°C) was described. The morphology of the hydrochars changed with reaction time increased, the surface of the materials contained a large number of functional groups, showed higher adsorption capacity for Cr (VI) than activated carbon and the removal rates of Cr (VI) were 67% and 29% respectively (pH=1, 20°C).

Abstract: Soy protein isolate (SPI)-essential oil monomers edible composite films were prepared by casting and solvent evaporation method. Films antibacterial activity and preservation effect on chilled pork were investigated. The results indicated that composite films showed significant inhibitory effect on the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas and yeast. And the antimicrobial activity of films containing cinnamaldehyde was the highest. The films containing 6% essential oil monomers had better preservation effect on the meat samples compared with those without package or packed with single SPI edible films.

Abstract: One-dimensional (1D) ZnO nanorods with different shapes and high aspect ratio were successfully synthesized using a cetyltrimethylammonium bromide (CTAB)-assisted or sodium dodecyl sulfate (SDS)-assisted hydrothermal process at 90°C for 5h. The surface morphology and structure of nanocrystals were characterized by FE-SEM and XRD. Experimental results showed that the typical morphology of ZnO crystals grown with additive of CTAB was pencil-like rods, while the ZnO crystals grown with SDS showed needle-like rods. The gas sensors had been fabricated using 1D ZnO powders to examine the response towards 40ppm NO2 in the range of operating temperature from 150 oC to 450 oC. Compared with needle-like ZnO crystals, the NO2 gas sensor based on pencil-like ZnO nanostructure had better selectivity at the same gas concentration.

Abstract: BiOCl nanosheets were annealed at different temperatures. The effect of annealing on structures and properties was characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic performance was evaluated by photodegrading Rhodamine B (RhB) under UV light irradiation. It was found oxygen vacancy defects (OVDs) could be generated during the annealing treatment and the best photocatalytic efficiency was obtained when the annealing temperature was 450 °C. The enhanced photocatalytic efficiency was ascribed to the high separation efficiency of the photogenerated electron-hole pairs due to the existence of the OVDs as positively charged centers.

Abstract: The sunlight activated photocatalysts are urgently needed for the applications of photocatalytic techniques to environmental pollutants removal. Herein, we report the one-step hydrothermally prepared CdS/TiO₂ nanocomposite photocatalyst that is active in the degradation of pollutant organic dyes under solar light. The morphology and components are confirmed by TEM, SEM and XRD. With methylene blue (MB) as the model pollutant organic dye, the photocatalytic activity of CdS/TiO₂ nanocomposite photocatalyst under sunlight is demonstrated, and 80% MB is removed after 120 minutes sunlight illumination. Besides, the influences of pH, the amount of photocatalyst and the addition of H₂O₂ on photocatalytic activity for the degradation of MB are also investigated to mimic water treatment process.

Abstract: This paper deals with removal of strontium ions from solution by expanding rice husk (ERH) in a fixed-bed column. The absorption characteristics of expanding rice husk for strontium ions were studied systematically. The effects of different column design parameters like bed depth, flow rate and initial strontium concentration on the equilibrium uptake of ERH for strontium ions were investigated. It was found that the equilibrium uptake (q_eq(exp)) of the ERH increased with the increase in initial strontium concentration but decreased with the increase in flow rate and bed depth respectively. Strontium cumulative removals of 2.32 mg/g were obtained under the optimum operational conditions at a flow rate of 10 ml/min and bed depth of 6 cm. XPS analysis indicated that the Sr (II) ion was absorbed on ERH. The adsorption data fitted well with the bed depth service time (BDST) model.

Abstract: A fast oil-absorption resin with high pore level was developed by concentrated inverse emulsion polymerization. The oil absorption rate test displayed that only 30 min was needed for the resin to reach absorption saturation. The property was elucidated by the fully interconnected porous structure of the resins. Besides, resins exhibited high oil retention percentage in terms of fast centrifuge speed test and high reusability in terms of the repetitive absorption/desorption test. The effect of different polymerization parameters, such as the amount of initiator, cross-linker and emulsifier, on the oil absorbency was investigated in detail. The experimental results showed that the absorptive capacity of the resin was 8.5 g/g for toluene and 15.8 g/g for chloroform under the optimized conditions. All these features indicate wide practice applications.

Abstract: Hexagonal lamellar crystals with 200-500nm in diameter and 50-100nm in thickness and fibrous morphological crystals with 100-300nm in diameter and 10-30μm in lengths are synthesized in hydrothermal conditions using MgCl₂ and NaOH as raw materials in this paper. The particles size, morphology and crystal phase of the Mg (OH)₂ particles as obtained are characterized with scanning electron microscopy (SEM) and X-ray (XRD). The results indicated that precursor concentration, temperature and time play an important role in formation of Mg (OH)₂ crystals. The Mg (OH)₂ particles display hexagonal lamellar morphology, when MgCl₂ solution concentration is less than 1.5mol/L. Fibrous crystals are growing, when MgCl₂ solution concentration is more than 1.5mol/L. Raising temperature and extending time is in favor of formation of fibrous Mg (OH)₂ crystals. A mechanistic interpretation of formation of Mg (OH)₂ crystals in hydrothermal condition is postulated. The interpretation that fibrous crystal is converted from hexagonal crystal is proved.

Abstract: Mg-based hydrogen storage material was prepared by ball milling, and then the material was used to react with CS₂. The morphology and hydrogen desorption properties of the hydrogen storage material as well as the CS₂ hydrogenation product were analyzed. Results show that in situ hydrogenation and desulfurization of CS₂ happens with the MgH₂ in the hydrogen storage material as hydrogen donator and desulfurizer at 300 °C and ordinary pressure, and MgS, CH₄ and H₂S are generated from the reaction. There is a coupling relationship between dehydrogenation of the hydrogen storage material and hydrogenation of CS₂. The addition of nickel and molybdenum show negative effect on the sulfur fixation capability of the Mg-based hydrogen storage material though they could decrease the dehydrogenation temperature of the material.

Abstract: N, Fe co-doped TiO₂ photocatalyst was synthesized by sol-gel method. The catalyst prepared was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Ultraviolet and visible spectroscopy (UV-vis). The results showed that the N, Fe co-doped TiO₂ prepared had the anatase structure. The absorption edge of the photocatalyst shifted to longer wavelength and photocatalytic activity for degradation of Methylene blue (MB) under Xe-lamp (350 W) was much more active than un-doped TiO₂, N-TiO₂ Fe-TiO₂ and P-25.