Advanced Materials Research Vols. 356-360

Abstract: Two kinds of hypercrosslinked resin ZH-01 and ZH-03 were prepared in this study. Experimental investigations were conducted to study the adsorption characteristics of 4-chlorophenol on the hypercrosslinked resins by method of static adsorption. The equilibrium adsorption data was fitted to Freundlich adsorption isotherm model to evaluate the related parameters. The results showed that the changes of enthalpy, free energy, entropy indicate an exothermic, spontaneous and disorder decreasing process happened in the adsorption. It was also shown that, respecting to the adsorption capacity, the adsorbents prepared here are better than the Amberlite XAD-4 for removing the 4-chlorophenol in aqueous solutions.

Abstract: The pH and nitrate effect on the anaerobic biological reduction of perchlorate using acetate as carbon source was studied. Perchlorate reduction occurred throughout the pH range from 6.0 to 9.0. However, initiation of perchlorate reduction was rapid under neutral pH conditions. At initial pH 7, perchlorate reduction followed pseudo-first-order with the reaction rate constants was 0.3732 d-1 and the half-life time was 1.85 d. In the absence and presence of nitrate, the kinetics of perchlorate reduction with the reaction rate constants were 0.3229 d-1 and 0.2307 d-1 (after a lag phase for 3 d), the half-life time were 2.1 d and 6 d. With multiple additions of nitrate, perchlorate removal was observed with a longer lag period, the consequent production of high level nitrite may delay perchlorate degradation.

Abstract: The inhibition kinetic parameters of pentachlorophenol (PCP) on bovine intestinal mucosa alkaline phosphatase (ALP) activity were studied by spectrophotometry. The results showed that PCP inhibited ALP activity in a concentration dependent manner, and the 50% inhibitory concentration (IC50) was estimated to be 4.20 mM. The apparent Michaelis–Menten constant (Km) and apparent maximum reaction rate (Vmax) was found to be decreased in the presence of PCP. Lineweaver–Burk plots indicated that the nature of the inhibition was of an uncompetitive type. Kinetic analysis indicated that the value of the inhibition constant (Ki) was 5.67 mM.

Abstract: Textile industries usually discharge colored effluents containing various dyes. These dyes usually contain more than one aromatic structure and they are not only difficult to be degraded biologically but also toxic. UV/semiconductor procedure, with advantages including photostability, non-toxicity, affordable price, and insolubility in water, has been studied and used. This aim of this study is to develop photocatalytic reactor with higher removal efficiency. The TiO₂ thin film was prepared by Sol-Gel method and coated on the surface of activated carbon to enhance the reaction opportunity and increase pollutants removal efficiency. Taguchi method was used to optimize preparing conditions. The results indicated that the best TiO₂ photocatalytic activity can be found when tetraisopropyl orthotitanate, isopropyl alcohol and acetic acid were mixed in the molar ratio of 1：2：8 under the calcination temperature of 500°C for 90 minutes. Further analysis of TiO₂ thin film by SEM, ESCA and XRD, the results showed that grain size of TiO₂ was about 17 nm and crystal structure mainly was anatase. The photocatalytic reaction rate increased 15~20% when the ratio of PAC in catalyst increased > 4%. The results suggested that recovery of the composited catalyst become easy because its volume and subsiding increased.

Abstract: Nasturtium officinale exposed to low temperature at 10-12°C was investigated to study the possible application of eutrophicated waterbody resoration in winter of some parts of China. The fresh weight, soluble protein and photosynthetic pigments as well as antioxidant enzymes and biomass changes were measured to study the effect of low temperature on the growth of this plant. The results demonstrated that the soluble protein of Nasturtium officinale at low temperature increased compared with that of plant that grown in optimum temperature, so this plant can synthesize higher level protein to resist low temperature stress. The biomass of Nasturtium officinale also increased at such low temperatures. SOD and POD activity increased to resist oxidative stress when the plant was exposed to low temperature of 10-12°C. CAT activity and MDA content of Nasturtium officinale did not change much at such low temperature. Only photosynthetic pigments decreased in low temperature compared with that of plant grown in optimum temperature.The plant did not suffer from seriously oxidative damage at such low temperature condition, so the plant is suitable for using in the wading eutrophicated natural waterbody restoratin in winter of some part of China.

Abstract: Lignocellulose/organic montmorillonite (LNC/OMMT) nanocomposites have been prepared by the solution intercalation method from pristine montmorillonite (MMT),using Cetyl three methyl brominated ammonium(CTAB) as the reactive compatibilizer between LNC and MMT .Then the nanocomposites were characterized by Fourier transform infrared(FT-IR),X-ray diffraction(XRD) and Scanning electron microscope(SEM).Diffferent preparation conditions influence of the adsorption property on nanocomposites for Congo Red were studied. The characterization results indicate that LNC molecules have intercalated into the interlayers of OMMT and increased its interlayer distance. The intercalated structure was formed in LNC/OMMT nanocomposits. The adsorption result show that the nanocomposits have higher adsorption capacity with weight ratio of LNC to OMMT 6:1, reaction temperature 50°C, reaction time 6 h, concentration of NaOH 10%.

Abstract: In the paper, tetranbutyl titanate was loaded on granular active carbon using sol-gel dip-coating technique to form anatase nano-TiO₂ photocatalyst with an average diameter of 16nm doped with N, Fe, Zn ions. The morphology and crystal structure were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV–Vis spectrophotometer, respectively. The results show that the prepared photocatalyst demonstrates outstanding photodegradation efficiency and light response zone has transferred from ultraviolet light zone to UV-visible zone. Moreover, considering methylene blue (MB) as target degradation pollutant, under visible light irradiation, the photodegradation rate reached beyond 100% after 1h.

Abstract: NiMgAlO catalysts were prepared by two methods: coprecipition and impregnation. They were used to simultaneously adsorb SO₂ and NO with O₂ in a fixed bed at atmospheric pressure. Typically the molar composition of the feed gas was 1% SO₂, 0.2% NO and O₂ with ultra-high purity Ar as the diluent. The results showed the catalysts were excellent materials for the simultaneous oxidation adsorption of SO₂ and NOx. The two kinds of catalysts were compared for the SO₂ and NOx adsorption capacity. The NiMgAlO catalyst prepared by coprecipition had better adsorption than impregnation. When NiMgAlO catalysts with 10 wt-% Ni content were calcined at 550°C, adsorption capacity was the largest at 120°C adsorption temperature: 1.392 mmol SO₂ and 0.213 mmol NOx were adsorbed on 1 g catalyst prepared by the coprecipition method. The causes are seen by the XRD, surface area and porous size analysis.

Abstract: It is assumed that the experimental adsorption capacity of phenolic compounds onto resin depends upon the molecular properties as well as background concentration of the aquatic system. The utility of this concept has been demonstrated by incorporating concentration as a parameter in quantitative structure-activity relationship (QSAR). DFT-B3LYP method, with the basis set 6-311G **, was employed to calculate quantum mechanical and physicochemical descriptors of phenolic compounds. The logarithm of the adsorption capacity of phenolic compounds on XAD-4 and ZH-01 investigated from the static experiment along with the descriptors mentioned above were used to establish QSAR models. The variables were reduced using stepwise multiple regression method, and the statistical results indicated that the correlation coefficient in the multiple linear regression (MLR) and cross-validation using leave-one-out(LOO) were 0.966, 0.920, 0.905 and 0.797, respectively. To validate the predictive power of resulting models, external validation was performed with Qext² values of 0.927 and 0.849, respectively. The developed models suggest that the adsorption mechanism of phenolic compounds onto XAD-4 and ZH-01 is different. Concentration, hydrophobic parameter are dominant factors governing the adsorption capacity of phenolic compounds onto XAD-4, while concentration and energy of the highest occupied molecular orbital are dominant factors controlling that of phenolic compounds on ZH-01. The consistency between experimental and predicted values indicates that the developed models can be used for estimating adsorption capacity of phenolic compounds onto XAD-4 and ZH-01.

Abstract: TiO₂ hollow microspheres were synthesized by a facile solvothermal method. The prepared samples were characterized by the XRD, SEM, TEM, BET and UV-vis. The results showed that the TiO₂ hollow microspheres offered an enhanced photocatalytic activity due to the multiple reflections of the UV light within the inner hollow structure.