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861.
The degradation products of polymers are identifiable by chromatography. The degradation product patterns (or fingerprints) formed depend on the type of polymer, the degradation mechanism(s), and also the type of additive present in the material. The chromatographic fingerprint of biotically aged degradable low-density polyethylene (i.e., LDPE+starch+prooxidant) shows, in particular, the absence of low molecular weight carboxylic acids, which suggests an assimilation of these carboxylic acids by the microorganisms. The degradation products of natural polymers are usually intermediates that are used again in the anabolic cycles. It is possible to transfer the terminology from the natural polymers, where the catabolism of natural polymers consists of three stages, and apply this also to the degradable synthetic polymers. During stage I the natural polymers degrade to their major building blocks (e.g., amino acids, glycerol, hexoses, pentoses, etc.), during stage II these products are collected and converted to a smaller number of even simpler molecules [e.g., acetyl-coenzyme A (CoA)]. In stage III, finally, the acetyl-CoA enters the citric acid cycle, where energy is gained in parallel with the release of CO2 and H2O.Presented at the international workshop,Polymers from Renewable Resources and their Degradation, Stockholm, Sweden, November 10–11, 1994. 相似文献
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Structural and photocatalytic properties of TiO2 films fabricated on silicon substrates by MOCVD method 总被引:3,自引:0,他引:3
Silicon(111) and Silicon(100) were employed for fabrication of TiO2 films by metal organic chemical vapor deposition( MOCVD).Titanium(Ⅳ) isopropoxide(Ti[O(C3H7)4]) was used as a precursor. The as-deposited TiO2 films were characterized with FE-SEM, XRD and AFM. The photocatalytic properties were investigated by decomposition of aqueous Orange Ⅱ. And UV-VlS photospectrometer was used for checking the absorption characteristics and photocatalytic degradation activity. The crystalline and structural properties of TiO2 film had crucial influences on the photodegradation efficiency. For MOCVD in-situ deposited films on Si substrates, the photoactivities varied following a shape of “M”: at Iower(350℃ ), middle(500℃ ) and higher(800℃ ) temperature of deposition, relative lower photodegradation activities were observed. At 400% and 700% of deposition, relative higher efficiencies of degradation were obtained, because one predominant crystallite orientation could be obtained as deposition at the temperature of two levels, especially a single anatase crystalline TiO2 film could be obtained at 700℃. 相似文献
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亚甲基兰分光光度法测定气态硫化氢方法研究 总被引:6,自引:1,他引:6
对气态污染物H2S测定方法亚甲基兰分光光度法进行了深入细致地探索研究,得出该方法最佳实验室测定条件,包括标准溶液和吸收溶液的选择,显色剂和样品的稳定时间,SO2、NOx对测定方法的影响以及样品的吸收效率等。实验结果表明,该方法校准曲线斜率为0.148~0.151吸光度/μgH2S·11mL,标准偏差1.2×10\+-3,环境监测样品回收率为84%~89%。 相似文献
869.
天然矿物锰矿砂对苯酚的界面吸附与降解研究 总被引:26,自引:0,他引:26
研究了天然矿物锰矿砂对苯酚的界面吸附与降解,结果表明锰矿砂对苯酚具有较强的吸附作用,较高温度,低pH值,固相与苯酚的较高质量比值有利于苯酚的吸附。吸附过程遵循二级反应动力学,吸附等温线为Langmuir型。应用简化的表面络合反应模式,求得了不同条件下的条件稳定常数及吸附苯酚的表面总吸附位。 相似文献
870.