Materials Science Forum Vol. 847

Abstract: In order to reduce the pollution of the waste material, the waste leather powder tanned with vegetable tannin was used in this work, and vinyitrimethoxy silane was chosen as coupling agent. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to investigate the thermal properties of the powder sample. Both thermal decomposition temperature and denaturation temperature of the modified sample were higher than those of the raw samples due to the interaction between leather powder and silane, which can be demonstrated by Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS) and Fourier Transform Infrared Spectroscopy (FT-IR). Additionally, the flowing property, hydrophilicity and water absorption rate of the powder samples was also examined. The results showed that the hydrophilicity and moisture absorption of the leather powder sample modified with silane was lower than the raw materials. And the flowing properties of the modified samples also decreased because of the coupling reaction of the flexible vinyitrimethoxy silane.

Abstract: Selective non-catalytic reduction (SNCR) is a denitration method in the high temperature area, and NH₃ or urea is used for SNCR as reducing agents to react with NO_X to produce N₂ in the flue gas in the temperature ranged from 850°C to 1100°C. The SNCR deNOx technology has been well used in utility boiler, but compared with it, the lower denitration efficiency and the larger consumption of ammonia indicate a more complex process in cement pre-calciner. Unlike in utility boiler, the presence of high concentrations of cement raw materials may influence SNCR denitration reaction process in cement kilns. Therefore, studying the effect of CaO which occupy the major composition of cement raw material is very important in SNCR process. In this study the influence of CaO on the SNCR deNOx process was investigated by simulating SNCR reaction at temperature that ranges from 750°C to 1100°C with different normalized stoichiometric ratio. The experimental results demonstrate that the addition of CaO increases the optimum denitration temperature to 1100°C, but it has no effect on normalized stoichiometric ratio. In the whole reaction process NH₃ not only restores NO to O₂ but also reacts with O₂ to NO. Since the adsorption of NH₃ on CaO surface, in the temperature range of 750°C-850°C the addition of CaO promotes the reaction of NH₃ and O₂ and increases NO_X concentration. However, in the temperature range of 850°C-1000°C it not only promotes NH₃ oxidation but also inhibits the reduction reaction of NH₃, thereby the denitration reaction is inhibited. In the temperature range of 1050°C-1100°C the denitration reaction is promoted due to the NH₃ desorption from CaO surface.

Abstract: A novel method was developed for degradation of phenolic waste water using horseradish peroxidase (HRP) immobilization on activated carbon/polyvinyl formal (AC/PVFM) composite materials in this study. The materials were black-sponge-like, soft and elastic, and had three-dimensional porous network structure. Optimum conditions of immobilized HRP carrier preparation technology was selected by orthogonal experiment. The enzymatic properties were explored and compared between immobilized and free enzyme. The optimum pH of immobilized HRP and free HRP were both 4, nevertheless, the immobilization of HRP increased the enzyme activity. The optimum temperature of immobilized HRP was 20°C which was lower than that of free HRP (25°C), therefore the immobilized HRP could resist to lower temperature. The K_m of immobilized HRP and free HRP were 0.23 mmol/L and 0.40 mmol/L, respectively. The lower K_m value of immobilized HRP indicated higher affinity to the substrate. These results show that HRP immobilized on AC/PVFM composite materials is promising in phenolic wastewater degradation.

Abstract: The development of the city traffic and its increasing traffic flux are the signs of the development of the society, but causing a serious pollution on the city's ecological environment. Cement hydration reactions are needed to generate Ca (OH)₂, C-S-H gel, and AFt, as well as other hydrated products. Meanwhile, heavy metal ions are contained and fixed in a cement paste under physical encapsulation, absorption, isomorphous replacement, and double decomposition. This paper mainly discusses the impact of hydration environment on the adsorption law of materials adsorbing heavy metal ions and the adsorption mechanism under different pH values and temperatures, analyzing specific reasons from the perspective of micro-structure. Through the analysis it can be seen that, in addition to zinc ions, the cement-based materials’ capacity of adsorbing heavy metal ions increases as the pH value and the temperature increase. Micro-structure analysis shows that cement-based materials’ main adsorption methods are different when pH values are different.

Abstract: A fast and simple method to allow routine analysis of waste phosphors was developed and fully validated. Pb, Hg in waste fluorescent lamps phosphors (WFP) and Pb, Cd in waste CRT phosphors (WCP) were quantified by inductively coupled plasma atomic emission spectrometry (ICP-OES). Analytical conditions, including choice of analytical spectral lines, sample dissolution methods and many other standards, were studied. Wavelengths of 220.353, 228.802, and 184.886 nm were selected as analytical lines for determination of Pb, Cd, and Hg respectively. Studies showed that, Nitric acid could be used for dissolving Cd and Hg, and alkali fusion method for Pb. Detection limits of Pb, Cd, and Hg found were 1.8, 0.3 and 3mg/kg respectively. The proposed method was used in determination of target elements in waste rare earth phosphors, giving values of recovery in the ranges of 96.5%-104%, 98.5%-105% for Pb, Hg in WFP, and 98%-104.5%, 98%-104.5% for Pb, Cd in WCP respectively, and values of RSD less than 8%. Also, influences by dilution factor, coexisting elements and HNO3 Concentration etc. were discussed in the paper.

Abstract: A IrO₂ anode on titanium substrate with iridium–titanium oxide interlayer (Ti/ TiO₂-IrO_x/IrO₂) was prepared through repeating brushing-drying-calcinating procedure. The TiO₂-IrO_x interlayer was prepared using a mixture of TiN nanoparticles and H₂IrCl₆ solution as the coating solution. The Ti/TiO₂-IrO_x/IrO₂ had high catalytic activity, good catalytic stability and long service life. It was suitable for the application of electrochemical depolymerization of chitosans. The experimental results showed that chitosan could be effectively degraded using the Ti/ TiO₂-IrO_x/IrO₂ as the anode. The influence of the current density on the degradation of chitosans was complicated. The power supply type obviously influenced on the degradation.

Abstract: A novel gas sensor for the determination of formaldehyde was developed based on molecular imprinting technique (MIT). MIT was for the first time used to recognize small organic molecule by our group. The molecular imprinting nanoparticles (MINs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using imprinting polymerization with formaldehyde as template and Ag-LaFeO₃ as substrate material. The structure of the MINs is orthogonal perovskite. And then the MINs were printed onto an alumina tube. Subsequently, a high selectivity molecular imprinting gas sensor for detection of formaldehyde was achieved. At 86°C, the response to 0.5 ppm formaldehyde based on the sensor is 16, and the response is lower than 2 for the other test gases. The response time and recovery time are 55 s and 40 s, respectively.

Abstract: MnO₂ nanoparticles were prepared by one-step redox under room temperature. The sample was characterized by XRD, SEM, TEM and FT-IR. The results indicated that the MnO₂ nanoparticles was amorphous δ-MnO₂ with the uniform size of 10-20nm in particle diameter, which can be seen by XRD patterns. The four peaks appear at 2θ = 23.24°,36.1°,45.42°and 64.38°, respectively. FT-IR results showed the 519 cm^-1 as Mn-O features manganese dioxide absorption. The effect of the pH, nanoMnO₂ dosage, reaction time, reaction temperature and initial concentration were studied on the removal of reactive brilliant blue. It was found that the removal ability of reactive brilliant blue was the best under the selected conditions: pH was 3.0, dosage of nanoMnO₂ was 0.05g, KN-R solution concentration was 5mg / L, reaction time was 2h, temperature was 25°C.

Abstract: Low-dimensional heterostructured functional materials have been widely applied in new energy materials, catalysts, et al. However, to enhance photo-response in visible light and the biocompatibility improvement are still the great challenges faced. And the dendrimers act good roles in transferring the drug and gene, and has good biocompatibility. Self-assembly on the surface of low-dimensional heterostructured functional materials with dendrimers holding-COOH groups was carried out in this paper. The characterizations of the materials were examined by SEM (scanning electron microscopy), XRD (X-ray diffraction), the Fourier-Transform Infrared (FTIR) spectra, ultraviolet-visible spectroscopy (UV-Vis) and so on. The photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate. The results indicated that ZnO/CuS modified with dendrimers showed good photo-response to visible light and 808 nm laser, the photo-response properties enhanced greatly by adding some small amount of grapheme oxide. Photocatalytic efficiency was examined by selecting typical organic pollutants, some good results were obtained. The external stimuli driven nanorobots for removal the organic pollutants or toxins in the living body have been developed.

Abstract: The radiation method was studied to prepare Pd-doped SiO₂ aerogels with different contents. The textural properties of the pristine SiO₂ aerogels and Pd-doped SiO₂ aerogels were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N₂ adsorption measurements. It can be concluded that there were large amounts of Pd particles presented in the framework of SiO₂ aerogels after radiation. In addition, the size of Pd particles increased with the increase of radiation dose. The introduction of Pd nanoparticles produced a reduction of the surface areas, total pore and mesopore volumes.