Advanced Materials Research Vols. 455-456

Abstract: Quantitative structure property relationship (QSPR) model for predicting the n-octanol/water partition coefficient, Kow, of 21 polychlorinated biphenyls (PCBs) was investigated. The structure of the investigated PCBs is mathematically characterized by using molecular distance-edge vector (MDEV) index, a topological index which is developed based on the topological method. The calibration model of Kow was developed by using radial basis function artificial neural network (RBF ANN). Leave one out cross validation was carried out to assess the predictive ability of the developed QSPR model. The R2 between the predicted and experimental logKow is 0.9793. The prediction RMS%RE for the 21 PCBs is 1.92. It is demonstrated that there is a quantitative relationship between the MDEV index and the Kow of the 21 PCBs. RBF ANN is shown to practicable for developing the QSPR model for Kow of PCBs.

Abstract: A practicable quantitative structure property relationship (QSPR) model for predicting the soil-water partition coefficient, Koc, of 16 polychlorinated biphenyls (PCBs) was developed. The structure of the investigated PCBs is encoded by five quantum structural descriptors and on topological index. The calibration model of Koc was developed by using artificial neural network (ANN). The input variables of ANN were generated from 6 structural descriptors by using principal component analysis (PCA). Leave one out cross validation was carried out to assess the predictive ability of the developed model. The prediction RMS%RE for the 16 PCBs is 6.35. The R2 between the predicted and experimental logKoc is 0.8522. It is demonstrated that ANN combined with PCA is a practicable method for developing QSPR model for Koc of these PCBs.

Abstract: - TiC/C composite fibers were prepared by vapor phase titanizing of the regular carbon fibers via chemical vapor deposition (CVD). The carbon fibers were titanized from the surface of the fiber to the core. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were applied to characterize the morphology and structure of the TiC/C composite fibers. The influences of CVD reaction conditions such as temperature and reaction time on the TiC particle size and the thickness of the deposited layer were investigated. Higher temperature and longer time resulted in the growth of bigger size of the TiC crystal particles, and the particle uniformity was also decreased.

Abstract: Mg–Al layered double hydroxide (Mg–Al LDH) was investigated for adsorption of dimethyl phthalate (DMP), di-(2-ethylhexyl) phthalate (DEHP) and dioctyl phthalate (DOP) from water samples. The adsorption capability of the Mg–Al LDH was compared with that of activated carbon. Adsorption of the three phthalate esters (PAEs) fitted pseudo-second-order kinetics, and the Langmuir or Freundlich equations described the adsorption isotherms. Adsorption of the PAEs was exothermic, and was mainly dominated by physical interactions including dispersion, induction, orientation and hydrogen bond forces. Compared with activated carbon, the Mg–Al LDH removal efficiency of the relatively small PAE, DMP, was about 20 % lower. The removal efficiencies of the larger PAEs, DEHP and DOP, were about the same on both sorbents. After three regeneration cycles of the Mg–Al LDH at 300 °C for 2 h, its adsorption capacity remained above 90 %. The infrared (IR) spectra and the X-ray diffraction (XRD) patterns for the Mg-Al-LDH before and after regeneration showed no large differences, which indicates that the structure of the Mg–Al LDH does not change after regeneration.

Abstract: .Reported accidents such as fire and explosion on account of lithium-ion batteries remind us it is important to understand the thermal stability of battery materials. Lithium salt plays an important role in the safety of lithium ion batteries. Thermal decomposition reaction of a lithium salt-lithium bis (oxalato) borate (LiBOB) was studied using C80 calorimeter under argon atmosphere. The samples were heated at a 0.2 K min^-1 heating rate from ambient temperature to 573 K in single scanning rate experiments, or at different constant temperatures (528 K, 533 K, 538 K, 543 K) in isothermal experiments. The results show that LiBOB decomposes near 433 K, and its decomposition reaction order was calculated to be n=1.43. In addition, thermodynamic parameters and kinetic parameters were obtained. The reaction heat associated with LiBOB decomposition process is 197.33 J g^-1, the activation energy and pre-exponential factor were calculated to be E=177.23 kJ mol^-1 and A=6.51×106 s^-1, respectively. Nomenclature

Abstract: Hydrogen-producing zymogenous bacteria YUAN-3 (Ethanoligenens harbinense) is used as the study object, on which the intermittent hydrogen production test is applied to examine the influence of Na-ion concentration on the growth and gas generation of YUAN-3. Research results show that when Na ion concentration is 1.5g/L, cell concentration reaches the maximum level 0.892g/L; when Na-ion concentration is maintained at 2.0~3.0g/L, culture medium is applicable for hydrogen generation of YUAN-3.

Abstract: Carbon dioxide reforming of methane over Ni/Mo/ La₂O₃-SBA-15 was studied. The catalyst was characterized by N₂ adsorption, X-ray diffraction, H₂-TPR,CO₂-TPD and TG-GTA analysis. The results indicated that the introduction of an appropriate amount of La₂O₃ exhibited a higher activity and stability. In the long term stability test, La₂O₃ impregnated Ni/Mo-SBA-15 gave the highest conversion and stable activity at 800°C for 250 h. The effect of La was suggested to be due to its lower tendency to carbon deposition. Characterization results showed a strong interaction between La and Mo or Ni which facilitated the improvement of catalytic performance.

Abstract: A low-cost solid acid catalyst derived from kaolin and sulphuric acid, was utilized for the removal of thiophene from coking benzene. The effect of various factors, such as sintering temperature, sintering time, acid treatment temperature, acid treatment time and the acid content, were investigated to improve the catalytic activity in the removal of thiophene, estimated by UV-vis spectrum. The results showed that kaolin calcined at 973 K for 6 h and refluxed for 3 h in 3 mol/L H₂SO₄ at 363 K displayed higher thiophene removal efficiency. The highest one was up to 93.05%. In that process, acetic anhydride was appended in order to improve the efficiency of desulfurization.

Abstract: This paper presents the experimental studies on an SCR system for a mobile heavy-duty diesel engine to reduce NO_x emission below Euro V emission limits. The test results obtained by one engine serving in China show that NO_x emission was reduced to 1.81 g/kWh with ESC and 1.66 g/kWh with ETC, the reduction efficiency of NO_x was reduced by about 80%, while the average NH₃ slip is kept below 6 ppm.

Abstract: The extraction process of jujube juice was optimized based on soluble solid and total acid contents in this study. A central composite design of response surface methodology involving liquid-solid ratio, extraction time, enzyme dosage and extraction temperature was used, and second-order model for the yield was employed to generate the response surface. The optimum condition for the process was determined as follows: liquid-solid ratio 8, extraction time 2.5h, enzyme dosage 0.25%, extraction temperature 50 °C. The soluble solid and total acid contents at the optimum condition were 10.48% and 0.78 %, respectively.