芬顿试剂对田菁胶的氧化降解

考察了芬顿试剂对田菁胶的氧化降解行为. 系统研究了H_2O_2和Fe~(2+)用量、温度和降解时间对田菁胶粘度的影响. 结果表明,H_2O_2和Fe~(2+)合适的体积比为2:1. 在较低的温度(25 ℃)和较短的时间(20 min)内芬顿试剂就能使田菁胶粘度下降90%以上. 另外,pH值的变化对其降解性能影响不大,显示了较好的降解效果.     

Na_2S_2O_8-Fe~(2+)对田菁胶的氧化降解行为研究

考察了Na2S2O8-Fe2+对田菁胶的氧化降解行为,系统研究了Na2S2O8和Fe2+用量、温度、降解时间和pH值对田菁胶粘度的影响。结果表明,Na2S2O8和Fe2+合适的体积比为3?1。在较低的温度(40℃)和较短的时间(20 min)内Na2S2O8-Fe2+就能使田菁胶粘度下降90%以上。另外,Na2S2O8-Fe2+氧化还原体系在酸性和中性条件下对田菁胶的降解都有良好的降解性能,考虑到在实际生产中的应用,我们认为中性条件下最合适。     

新型Fenton试剂氧化降解有机物

新型Fenton试剂氧化降解有机物;次氯酸;Fenton试剂;降解有机物     

环保型田菁胶胶黏剂的研究

以田菁胶、聚乙烯醇为主要原料,水为溶剂,通过加入氧化剂、糊化剂、交联剂,再辅以催干剂、抗冻剂、消泡剂等,制备出改性田菁胶胶黏剂。采用单因素实验,考察了氧化剂种类、氧化剂用量、糊化剂用量、交联剂用量等因素对产品性能的影响,优化出产品的最佳合成工艺。结果表明,最佳的合成工艺为水140 g,田菁胶10 g,氧化剂1.5 g,糊化剂0.33 g,交联剂0.0185 g,氯化钙2 g、抗冻剂、消泡剂适量。在此条件下合成的产品黏度为60~70 Pa·s。     

田菁胶、羟丙基田菁胶和瓜胶的分子量及其分布研究

用凝胶色谱（ＧＰＣ）法测定了羟丙基田菁胶（ＨＰＳ）、田菁胶（ＳＧ）和瓜胶原粉（ＧＧ）三种样品的分子量,其重均分子量顺序Ｍ＿（ＷＨＰＳ）＞Ｍ＿（ＷＧＧ）＞Ｍ＿（ＷＳＧ）,分子量范围为２．３×１０￣５～３．４×１０￣５,分散系数关系为Ｄ＿（ＨＰＳ）＝Ｄ＿（ＳＧ）＞Ｄ＿（ＧＧ）,并讨论了聚糖的多分散性与产品性能的关系。     

瓜尔胶及其衍生物的过硫酸铵氧化降解研究

通过考察90℃,0.5‰过硫酸铵对瓜尔胶、羟丙基瓜尔胶及其羧甲基羟丙基瓜尔胶不同时间的氧化降解反应,发现开始时瓜尔胶主链主要是以糖苷键断裂的降解为主,当降解到一定程度后,才出现糖链上糖环的氧化。瓜尔胶的结构对降解反应有着很大的影响,而且降解速度:羧甲基羟丙基瓜尔胶羟丙基瓜尔胶瓜尔胶。形态观测结果表明氧化降解对微观结构有一定的影响。     

羟丙基田菁胶的结构研究

本文用IR、~(13)C-NMR、~1H-NMR、MS、元素分析手段对田菁胶原粉和环氧丙烷反应的合成样品进行系统地结构研究,证明样品为羟丙基型半乳甘露聚糖类,其主结构与田菁胶原粉一致,并用~1H-NMR法测定了羟丙基田菁胶的醚化度(D.S).     

田菁胶负载钯催化Heck反应的研究

通过较简单的方法合成了田菁胶负载钯化合物,利用XPS、IR、TG、DTA和TEM等手段对其进行了表征.该化合物在空气氛围中就能很好地催化丙烯酸、苯乙烯和丙烯酰胺与芳基碘的Heck反应,高产率(≥85 % )且立体选择性地生成取代的反式肉桂酸、1,2- 二苯乙烯和肉桂酰胺.化合物具有较好的重复使用性能.催化剂中起催化作用的是金属态的钯.     

两性田菁胶在处理生活污水中的助凝作用

研究了以聚合硫酸铁为主凝剂、两性田菁胶(ASG)为助凝剂处理城市生活废水的各种影响因素.实验结果表明:聚合硫酸铁和两性田菁胶分别以200mg/L和10mg/L的复配浓度、pH值接近7时混凝效果最佳,CODCr去除率达到近80%,处理后废水CODCr达到国家排放标准.     

季铵型阳离子田菁胶的制备及絮凝作用

季铵型阳离子田菁胶的制备及絮凝作用;化学改性;混凝     

Synergistic Flame Retardancy of Phosphatized Sesbania Gum/Ammonium Polyphosphate on Polylactic Acid

Phosphating sesbania gum (DESG) was obtained by modifying sesbania gum (SG) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and endic anhydride (EA). The structure of DESG was determined using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (¹H-NMR). Flame-retardant polylactic acid (PLA) composites were prepared by melt-blending PLA with DESG, which acted as a carbon source, and ammonium polyphosphate (APP), which acted as an acid source and a gas source. The flame retardancy of the PLA composite was investigated using vertical combustion (UL-94), the limiting oxygen index (LOI) and the cone calorimeter (CONE) test. Thermal properties and morphology were characterized via thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM), respectively. Experimental results indicated that when the mass ratio of DESG/APP was equal to 12/8 the LOI value was 32.2%; a vertical burning test (UL-94) V-0 rating was achieved. Meanwhile, the sample showed a lowest total heat release (THR) value of 52.7 MJ/m², which is a 32.5% reduction compared to that of neat PLA. Using FESEM, the uniform distribution of DESG and APP in the PLA matrix was observed. The synergistic effect of DESG and APP effectively enhanced the flame retardancy of PLA. Additionally, the synergistic mechanism of DESG and APP in PLA was proposed.     

Fenton试剂降解水中的菲和芘

多环芳烃(PAHs)是最早发现且数量最多的致癌物[1],主要来源于人类活动和能源利用过程,如石油、煤等的燃烧、石油及石油化工产品生产、海上石油开发及石油运输中的溢漏等过程.     

Oxidative Degradation of 2,4‐Dihydroxybenzoic Acid by the Fenton and Photo‐Fenton Processes: Kinetics,Mechanisms, and Evidence for the Substitution of H2O2 by O2

The kinetics and mechanisms of the oxidative degradation of 2,4‐dihydroxybenzoic acid (2,4‐DHBA) by the Fenton and photo‐Fenton processes were investigated in detail by a combination of HPLC, IC, and TOC analyses. The formation of 2,3,4‐trihydroxybenzoic acid (2,3,4‐THBA) at an early oxidation stage shows that hydroxylation of the aromatic ring is the first step of the process. This intermediate was able to reduce Fe^III and to contribute to the recycling of Fe^II. Complete mineralization could only be achieved under irradiation (photo‐Fenton). A detailed study of the dependence of the rate of mineralization on the concentration of H₂O₂ and dissolved O₂ was carried out. It was found that, even at a low initial concentration of H₂O₂, mineralization by the photo‐Fenton process was complete in a relatively short time, provided that the O₂ concentration was high enough, indicating that O₂ may, at least in part, substitute H₂O₂. Channeling reaction pathways toward O₂ rather than H₂O₂ consumption is of particular interest for the technical development of the photo‐Fenton process.     

A Study of Oxidative Degradation of Plastics by GC and GC-MS

Abstract

The behaviour of plastics, namely, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamide and some copolymers, was studied in a combustion chamber in which the conditions of large-scale fires were simulated. Volatile combustion products were frozen-out or analyzed directly on two columns, one packed with Porapak Q and the other capillary column coated with squalane or CP Sil 5 CB. Carbonyl compounds were determined as the 2,4-dinitro-phenyl hydrazones on an OV-101 stationary phase. Thermal conductivity and flame ionization detectors were used. The decomposition products were identified either on the basis of retention data (retention indices) or by combined capillary GC-MS. The data obtained are used for the cataloguing of plastics from the point of view of their product toxicity during fires.