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The Influence of Pair Spiral Extrusion Equipment on Thermoplastic Potato starch

合成化学 2004年第Z1期12卷 106-106页

作者： Wang Qing-ning 1, Feng Hui-xia 1, Ye Qi-zhi 2 1. College of petrochemical technology, Lanzhou Univ. of Sic. and Tech., Gansu 730050, China 2. Information central for resources and environmental science, C.A.S., Gansu 730000 China College of petrochemical technology Lanzhou Univ. of Sic. and Tech. Gansu 730050 China Information central for resources and environmental science C.A.S. Gansu 730000 China

Owing to contain a great deal of hydroxyl in Potato starch, between the molecules and inside of molecules have very strong hydroxyl action. Thus, the liquate temperature is higher than disintegrate temperature, so it is difficult to process. Under the microscope, the microcosmic construction is a polar crystal molecule, and it appears globe *** make the original potato starch into possession thermoplastic, we must make molecule of starch to change construct into amorphous state to form thermoplastic starch colophony. Besides auxiliary agent, shearing stress, temperature, time, pressure and hydrous quantity can affect the quality of starch thermoplastic too. The pair spiral extrude machine is used widely as the machines that are based of the pressure difference, and this extrude course may suffice *** the machine of pair spiral extrude of specific combination in the test of thermoplastic starch, the potato starch can be turned into thermoplastic starch of denaturalization preferably under auxiliary agent, shearing stress, temperature, pressure and the certain hydrous *** the action of the technology process condition and the spiral combination, potato starch grains expand and fragmentate; hydroxyl bond cleave between and inside of molecules. Thus, crystallize state is changed into amorphous state. The transmutation of starch molecule property may be seen clearly from X diffraction chart and analyses of the construction property,By means of the denaturation, the crystal area of potato starch is broken,its crystallization degree is decreased,and its molecular chains are in amorphous state. The hydrogen bond among the molecular chain is broken or removed so that the starch structure is changed, making the starch *** processing of thermoplastic starch advances a higher requirement of ingredient water content, and technical conditions. A remodeled twin-screw extruder is used to create an environment to realize the condition of de

关键词： thermoplastic starch, thermoplastic process, machine of pair spiral extrude.

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Removal of hexavalent chromium from aqueous solution by iron nanoparticles

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2005年第10期6卷 1022-1027页

作者：牛少凤刘永徐新华楼章华 Department of Environmental Engineering Zhejiang University Department of Environmental Engineering Zhejiang University Hangzhou 310027 China School of Civil Engineering and Architecture Zhejiang University Hangzhou 310027 China

Groundwater remediation by nanoparticles has received increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe0) nanoparticles. Cr(VI) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(VI), is an option in the remediation of contami- nated sites, transforming Cr(VI) to essentially nontoxic Cr(III). At a dose of 0.4 g/L, 100% of Cr(VI) (20 mg/L) was degraded. The Cr(VI) removal efficiency decreased significantly with increasing initial pH. Different Fe0 type was compared in the same con- ditions. The reactivity was in the order starch-stabilized Fe0 nanoparticles>Fe0 nanoparticles>Fe0 powder>Fe0 filings. Electro- chemical analysis of the reaction process led to the conclusion that Cr(OH)3 should be the final product of Cr(VI). Iron nanopar- ticles are good choice for the remediation of heavy metals in groundwater.

关键词： Hexavalent chromium, Iron nanoparticles, starch, Stabilize, Remediation

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