Papers by Author: Hai Feng Chen

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Authors: Pei Song Tang, Hai Feng Chen, Feng Cao, Guo Xiang Pan, Min Hong Xu
Abstract: The Nano-Bi2MoO6 was prepared using Bi(NO3)3•5H2O and Na2MoO4•2H2O as starting materials by a hydrothermal process. The prepared Bi2MoO6 product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). It was found that the prepared nano-Bi2MoO6 show narrow band gap of 2.88 eV. Consequently, the prepared nano-Bi2MoO6 show high visible-light photocatalytic activity for decomposition of Rhodamine B in comparison with the commercial Degussa P25, which was ascribed to the visible-light absorption.
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Authors: Hai Feng Chen, Jian Hua Zhu, Ye Zhen Sun, Miao Gen Qian
Abstract: This resistance by tests to simulate the sputtering thickness distribution and the relative value, we try to reduce the degree of uneven thickness by designing baffle shape for the coating equipment. In view of the structural characteristics of the device and the deposition of complex principles, theory and practice there are still some gaps, according to the measured data (resistance value) to be constantly revised to optimize and baffle design to achieve greater uniformity of product thickness. For example, to meet the resistivity greater than or equal 9.6 Ω and the average transmittance above 80%, TiO2/Ag/TiO2 film fully met the requirements of practical applications by applying improved baffle. Concluding remarks are stated at the end of the abstract text. Based on the use of a simple baffle design and improvement, we had achieved good results in mastering the sputtering parameters.
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Authors: Hai Feng Chen, Pei Song Tang, Min Hong Xu, Feng Cao
Abstract: The present investigatory founded an effectiveness of inexpensive and eco-friendly alumina silicate clay minerals, sericitic pyrophyllite (SP), as an adsorbent for the possible application in the absorption of K+. The crystal structure of pyrophyllite, size and morphology were characterized by XRD and SEM. In addition to pyrophyllite, quartz and were also contained in the minerals. The area of lamellar SP was about dozens um2. The results showed that potassium was absorbed on the SP under different pH and concentrations, and the best condition was pH=6, the time of equilibrium absorption = 30 min. It has been found that these natural minerals are effective in removing 55−75% of K+ from 5.0 to 20 mgL-1 KNO3 solutions. The applicability of the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms in each case of potassium was examined separately. We found that the adsorption process was endothermic in the case of SP and the Freundlich adsorption model was to more suitably represent the data. The work could provide the theoretical basis of the study of potassium ions adsorbed by pyrophyllite applying in fertilizer.
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Authors: Jun Jun Wu, Hai Feng Chen, Shi Jiang Zhao, Bin Li
Abstract: Pyrophyllite was the cheap, environmentally friendly alumina silicate clay minerals. This paper studied optimization of conditions for extraction of acid-soluble Al2O3 from pyrophyllite. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by using scanning electron microscopy. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C and hydrochloric acid concentration was 25%, the dissolution amount of alumina largest. The fit results indicated that the research for the relationship between dissolution and time by Using Exponential function series Asymptotic1 model to fitting match was the best. So the above function could be used to estimate each time the dissolution of alumina from pyrophyllite in hydrochloric acid.
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Authors: Hai Feng Chen, Pei Song Tang, Feng Cao, Min Hong Xu
Abstract: Using paraffin as phase change material, expanded perlite (EP) as porous materials, the EP/paraffin was prepared by vacuum impregnation treatment and tested by scanning electron microscopy (SEM). Adding other building materials, cement bricks based paraffin (CBBP) for thermal energy storage were molded and tested by means of water absorption, compressive strength and actual working of thermal energy storage. The testing results showed that paraffin was absorbed into the holes and cracks of EP, and CBBP had not linear change of various properties versus amount of cement or paraffin. Its mechanical strength was full compliance with national standard GB 21144-2007-T. At last, by phase change material exothermic or endothermic, CBBP effectively regulated outdoor surface temperature in summer: in temperature rising stage, CBBP was 4.63 °C lower than general cement bricks (GCB, no paraffin); in the cooling stage, CBBP was 2.30 °C higher than GCB.
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Authors: Jun Jun Wu, Hai Feng Chen, Shi Jiang Zhao, Bin Li
Abstract: This paper studied the influence of heat treatment on the pyrophyllite structure and acid-soluble properties of alumina. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by XRD, TG-DTA, FT-IR and quantitative analysis of Al2O3. The quantitative titration method studied the dissolve characteristics of the different heat treatment samples in different acid conditions, and then a numerical simulation was done. The results showed that at temperatures below 480 °C, the pyrophyllite did not change the basic structure. 480~700 °C dehydroxylation reaction occurred, and the structure water of pyrophyllite is removed, and then turned into partial pyrophyllite. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C, the dissolution amount of alumina was largest. These works could provide some theoretical basis for further application of pyrophyllite research.
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Authors: Pei Song Tang, He Sun, Feng Cao, Jin Tian Yang, Sheng Liang Ni, Hai Feng Chen
Abstract: The LaNiO3 nanoparticles were prepared by a sol-gel process. The LaNiO3 nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). XRD and SEM demonstrate the successful synthesis of single phase perovskite LaNiO3 and an average grain size of 80 nm in diameter. It was found that the as-prepared LaNiO3 shows strong visible-light absorption with absorption onset of 545 nm, indicating a narrow optical band gap of 2.28 eV. Consequently, LaNiO3 nanoparticles show high visible-light photocatalytic activity for decomposition of methyl orange in comparison with the commercial Degussa P25. The photocatalytic experiment shows the high photocatalytic activity for the decomposition of methyl orange under visible-light irradiation, which is attributed to the strong visible-light absorption.
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