Advanced Materials Research Vols. 538-541

Abstract: Catalyst with manganese oxide highly dispersed on granular activated carbon (MnOx/GAC) was fabricated by impregnating GAC in MnCl₂ solution and characterized by several techniques. The performance of manganese catalyst was investigated in catalytic ozonation of 4-chlorophenol in water. Manganese catalyst exhibits better efficiency than the original granular activated carbon, due to the synergic effect between activated carbon and manganese oxide. MnOx/GAC, produced by a simple methodin situ, is promising in catalytic ozonation of refractory organic pollutants in waste water.

Abstract: The nanocrystalline perovskite La-Mn-O hollow microfibers were prepared by the gel-precursor transformation process from reagents of metal salts and citric acid. The gel precursor and resultant products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The specific surface area was measured by the Brunauere-Emmette-Teller method. The catalytic performance of soot combustion was evaluated by thermo-gravimetric analysis under model conditions. The nanocrystalline La-Mn-O hollow microfibers calcined at 650 °C for 6 h are characterized with diameters of 2-8 µm, aspect ratios (length/diameter) about 5-15, a micro-tunnel with an estimated ratio 1/3 of the hollow diameter to fiber diameter, and a high specific surface area of 36.7 m2/g that is 1.9 times higher than the counterpart nanosized powder. This nanocrystalline La-Mn-O hollow microfibers catalyst exhibit a high catalytic activity for the soot combustion, with a low T50 of 397°C, which is largely owing to the high surface area and the micro-tunnel structure.

Abstract: The concentration signal of silica powder in the fluidizing gas i.e. air under different operation conditions were determined. The pretreating effects of concentration signal of silica powder by low pass filtering, wavelet transform de-noising and wavelet packet de-noising were compared. And the optimum method of de-noising has been determined.

Abstract: In this paper, we prepared foaming silicon rubber (PVMQ) /isobutylene-isoprene rubber (IIR) composites with chemical foaming technology. The DMA tests results showed that these foaming materials have effective damping characteristics in a wide temperature range. With the special vibrator, we found that the PVMQ/IIR foams that we prepared were the damping materials which has wide frequency domain, because they can keep high damping ratio in a wide frequency domain. When the preloading was between 1.0 mm and 1.7 mm, the structural damping did not change obviously. According to tests, we found that the damping ratio of these foams was fit to the simple equation .

Abstract: Original construction solutions for two types of fine bubble generators whose nozzles are manufactured by electroerosion are presented. The differential equation of the transfer speed of the oxygen towards water is numerically integrated and theoretical results are presented. A setup for experimental tests regarding the functioning of fine bubble generators was designed and built in the frame of the laboratory. Measurements regarding the increase of the concentration of oxygen dissolved in water were performed. Theoretical and experimental results were compared.

Abstract: An instrument is proposed for nitrate in situ monitoring in deep sea. It consists of a UV spectrophotometer, a deuterium lamp of high stability and low power consumption, a rugged and high-throughput retro-reflection probe and a center control board with large data storage capacity. With a measurement precision of nitrate concentration of 1μmol/l and a resolution of 0.5μmol/l, the instrument is able to measure nitrate concentrations from 0.5μmol/l to 320μmol/l. The system can automatically deduct the dark current to rectify the effect of temperature drift and correct the overall absorbance drift caused by instrument drift through integration of relative absorbance (IRA) algorithm. The system can endure the pressure at up to 1500m deep sea and carry out automatic long-term in situ detection of nitrate with high stability without needs for any manual intervention.

Abstract: In this paper, phase equilibrium of MgCl2-LiCl-Na2SiO3-H2O system at 180°C was researched. The solid phases were characterized by X-ray diffraction (XRD). Lithium silicate, hectorite, karpinskite and magnesium hydroxide were observed as solid phases. According to the analysis of XRD, the phase diagram was obtained. The phase diagram could be used as the theoretical principle for synthesis of hectorite and comprehensive utilization of concentrated natural brine.

Abstract: Gepolymeric material is a new building material, which not only has the characteristics of organic polymer, ceramic and cement but also unique properties. The effects of four factors on the strength of fly ash and metakaolin based geopolymer were discussed with the orthogonal tests in this study, including fly ash content, NaOH solution concentration, solid-liquid ratio and the content of sodium silicate in the liquid phase. The results show that: content of fly ash 30%, NaOH solution concentration 12mol/L, solid-to-liquid ratio 4.5 and the content of sodium silicate in the liquid phase 65% is the best condition preparation of fly ash and metakaolin based geopolymer.

Abstract: The corrosion inhibition behaviour of four selected Mannich bases compounds,namely 3-((N-methyl,N-phenyl)-methyl)2,4-Acetylacetone(MPMAA),3-((N-phenyl)-methyl) 2,4-Acetylacetone (PMAA),3-((N, N-diethyl)-methyl) 2, 4-Acetylacetone(DMAA) and 3-((N, N-methyl)-methyl) 2, 4-Acetylacetone (MMAA) as corrosion inhibitors for mild steel in 1M HCl solutions. Tafel polarization methods were performed to determine the corrosion parameters and inhibition efficiencies. Experimental results showed that PMAA is an excellent inhibitor for mild steel corrosion in 1M HCl solutions; showing a maximum efficiency 92.3% at concentration of 40mg/L. Polarization studies showed that the Mannich bases compounds can be regarded as mixed-type inhibitors and the inhibition efficiency of the four inhibitors followed the order PMAA > MPMAA > DMAA > MMAA. Then scanning electron microscope (SEM)techniques were also employed to examine the mechanism of corrosion inhibition property.

Abstract: Trichloracetic acid (TCA) was used to denature the enzymes that hydrolyze polyphosphates in frozen aquatic product and the polyphosphates were determined by using ion chromatograph with suppressor conductivity. The results showed that TCA could block the enzymatic hydrolysis of pyrophosphate and tripolyphosphate. The instrument was Dionex ICS 2000 ion chromatograph. The KOH solution was used as the. Ionpac AS11-HC separator column with gradient elution by KOH solution and suppressed conductivity detector were used for determine orthophosphate (Pi), pyrophosphate (PP), tripolyphosphate (TPP), and hexametaphosphte (HMP). The method was linear at concentration raging from 0.005 mmol•L^-1 to 0.5mmol•L^-1. The average recoveries ranged from 99% to 111%. The method can be applied for determination of phosphates in aquatic products.