松花江水源水深度处理过程水质生物稳定性研究

哈尔滨市目前供水水源地主要为磨盘山水库,而松花江作为哈尔滨市的传统水源地过去发挥了重要的作用,可否作为哈尔滨市的战略水源地已引起人们的广泛重视.本文围绕着松花江源水深度处理开展了系统深入研究,提出在常规处理工艺的基础上,采用臭氧预氧化结合活性炭工艺组合进行深度处理,重点考察不同处理单元的生物稳定性问题,并分析了AOC(生物可同化有机碳)作为生物稳定性控制指标的可靠性.研究结果表明:AOC数值的大小可以准确地评价松花江源水深度处理的效果.     

分子量及其分布的测量方法在生物高分子领域中的应用

分子量是生物高分子性质的一项重要参数,决定了生物高分子的许多理化特性和生物效应.准确测定生物高分子的分子量有利于了解其性质,是其有效应用的前提.文章主要简述了近年来常用的测定生物高分子分子量的方法,如黏度测量法、凝胶渗透色谱法、基质辅助激光解暖-飞行时间质谱法、电喷雾电离质谱法,并对其进行分析和比较,为微生物合成生物高...     

水源中溶解性有机物分子量分布特性研究

针对石家庄市地表水源的特点,进行测定分析,以确定有机物分子量分布特性.通过一个水文年的研究结果表明:石家庄地表水源水的共同特性是大分子量(＞10 000 Dalton)和小分子量(< 3000 Dalton)的有机物占有机物总量的绝大多数,而处于中间范围分布的有机物相对较少.     

水中残留有机物分子量分布特征和对膜性能的影响

本试验分析了城市二级处理水的残留有机物分子量分布特征及对超滤膜过滤透水性能的影响,并利用混凝法,活性炭吸附,臭氧-活性炭吸附进行了处理。研究结果表明：（1）城市污水厂二级出水中溶解态有机物主要集中在〈2k分子量区间上;（2）混凝处理后,高分子量有机物低分子化效果明显;PAC吸附能有效去除小分子量有机物;臭氧-PAC联用,大分子量有机物和小分子量有机物所占比例均有所下降,表明臭氧氧化与PAC吸附联用在去除有机物方面具有很好的互补性;（3）分子量分布对原水的透水通量影响较大;选择混凝、PAC或臭氧-PAC等作为膜法处理的预处理单元,对城市污水再生处理具有重要价值。     

凝胶色谱法在聚丙烯分子量及分子量分布测定中的应用

根据聚丙烯在凝胶色谱柱上的淋洗特点,确定了测定其分子量及分子量分布试验条件;采用示差和黏度双检测凝胶色谱系统,利用普适校正方法,不需要Mark常数K、α值,可直接测定聚丙烯分子量分布并给出分子量分布曲线;采用统计方法计算数均分子量、重均分子量、黏均分子量,可以为课题研究提供一定的依据和指导。     

膜生物反应器中有机物分子量分布特性

本研究将空间排阻液相色谱和示差折光检测器联用,测定膜生物反应器中有机物的分子量分布特性并进行定量分析。实验结果表明：大分子量物质是膜污染物的主要组成部分,投加适量铁盐可有效去除部分大分子量物质,延缓膜污染。     

超高分子量聚乙烯分子量及分子量分布的测定

超高分子量聚乙烯UHMWPE的分子量和分子量分布直接影响其加工性能和机械性能,然而传统的凝胶色谱法(GPC)存在一定的局限性,粘均分子量难以全面反映UHMWPE的结构特点。为了开发出一种精度高、重复性好的UHMWPE分子量和分子量分布测试方法,本研究在常规高温GPC设备的基础上,基于溶液流动分级机理,选取了合适凝胶孔径的凝胶色谱柱,改善了普通GPC测试结果分子量分布偏宽的问题。并通过对UHMWPE/三氯苯溶解方法的深入研究,解决了普通GPC测试结果重复性差的问题。对UHMWPE新产品的研发和后期的加工有着重要的实际意义。     

东平河水源水中有机物分布特性探讨

采用超滤法对东平河下游南海桂城段水源水中的有机物进行分子量测定,以确定水源水中有机物的分布特性。发现东平河该段水源水以小分子有机物为主,分子量小于3000的有机物约占67%,其次是分子量大小在10000~30000之间的有机物,约占12%。     

曝气生物滤池在污水处理中的研究及应用现状

曝气生物滤池(BAF)是一个浸没式的曝气三相反应器,该反应器通过生化反应和过滤作用去除污染物。经过二十几年的发展,BAF工艺不仅成为滴滤池和活性污泥法等二级处理工艺的革新竞争工艺,同时还是一种优良的深度处理工艺和微污染水源水预处理工艺。文章通过总结BAF工艺在国内外的研究进展及其各种形式的应用现状,指出了该工艺现存的一些问题,以及需要重点研究的方向。     

明胶分子量分布测定和表征的研究进展

<正> 目录 1.导言 2.明胶分子量分布范围 3.与分子量分布有关的一些重要物理性质 4.早期使用的方法 5.高压液相色谱(HPLC)法 6.SDS-PAGE法 7.HPLC和SDS-PAGE法的比较 8.回顾与展望     

不同给水处理工艺对饮用水生物稳定性的影响

可同化有机碳(AOC)和生物可降解溶解性有机碳(BDOC)是评价饮用水生物稳定性的指标,作者论述了各种饮用水处理工艺对AOC和BDOC影响研究的进展,并指出:为了获得生物稳定性饮用水,把不同净水工艺优化组合,在常规工艺基础上增加生物预氧化、活性炭等深度处理工艺是饮用水处理工艺改进的主要方向,膜分离技术则是未来饮用水处理技术的发展方向。     

Dynamic optimization for grade transition processes using orthogonal collocation on molecular weight distribution

To meet the demands of a competitive market, an industrial plant often produces several grades of polymer product through the same process in an economical way. As molecular weight distribution (MWD) is a crucial quality index of polymers, dynamic optimization for grade transition based on MWD is highly important, but challenging. This study considers the development of optimization models for MWD-based grade transition. An MWD reconstruction method using orthogonal collocation in two dimensions is developed to capture the dynamic feature of MWD in time and the distributive feature in chain length. The simultaneous collocation approach is adopted to discretize the model. Two optimization formulations are proposed to describe minimizing the transition time as well as off-spec production. Both formulations inherit the advantages of the simultaneous collocation approach. The numerical results show that the proposed methods can efficiently solve the grade transition problem with MWD specification, and obtain high performance control profiles to reduce the production cost. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1198–1210, 2019     

Molecular weight characterization of polybutadiene rubber with high molecular weight and broad molecular weight distribution

Following the molecular weight characterization of two polybutadiene samples, it was found that M _w from gel permeation chromatography with universal calibration and light scattering were in agreement, but M _n by gel permeation chromatography was less than M _n from membrane osmometry. A more detailed analysis revealed that the high molecular weight and broad molecular weight distribution of the two samples forced two corrections to the membrane osmometry results for (a) diffusional layer effects caused by high solution viscosities, and (b) solute permeability of the membrane. In the latter effect, the high viscosities of the solutions prevented actual diffusion through the membrane, but “reflection” of these species as defined by the Staverman coefficient prevented an accurate M _n determination. After making these corrections, it was found that M _n from membrane osmometry using a very tight membrane was in very good agreement with M _n from gel permeation chromatography. A method is demonstrated for obtaining M _n from a combination of membrane osmometry and gel permeation chromatography, where membrane osmometry data from membranes of different porosities (after corrections for diffusional layers and membrane reflection) are used to verify the accuracy of the gel permeation chromatography data as representing the true molecular weight distribution, allowing the gel permeation chromatography data to be used to calculate M _n.     

聚丙烯熔体流动指数与分子量及其分布的关系

研究了聚丙烯(PP)的熔体流动指数(MI)与聚合物不同分子量之间的关联性,对于分子量分布较窄的PP,数均分子量(Mn)、重均分子量(Mw)和粘均分子量(Mv)均能较好的关联;反之,MI与Mn关联性下降,而MI与Mn和Mv的关联性仍很好,尤其是MI与Mv的关联性受分子量分布的影响很小;MI与Z均分子量的关联性很差。同时．确定了MI与各种分子量之间的关联式,该式用于本体PP工艺反应器内氢气浓度的计算和MI的预测,与实验测量结果吻合良好。     

High speed molecular weight distribution

It is now possible to do molecular weight distribution of polymeric material almost as fast as you can put them in solution. μSYRAGEL® has opened a new era in the determination of molecular weight distribution of polymers. With operational efficiencies of 800 plates/min., one can obtain a molecular weight distribution in 15 mins. Combining three of the newest advances in liquid chromatography—solvent delivery, septumless injection, and μSYRAGEL—now makes it possible to use molecular weight distribution as a quality control tool in polymerization and fabrication. The reproducibility of the molecular weight distribution is now good enough that overlays can be done from the raw data. The chromatograms can be used right off the recorder. The reproducibility of the weight average and number average molecular weight is 2–3 percent.     

臭氧高级氧化技术在工业废水中的研究进展

对近几年来臭氧用于废水处理中研究进展进行了综述,主要介绍了非均相臭氧催化剂工艺、O_3/H_2O_2、O_3/UV三种工艺的研究现状,并对其他一些组合一些工艺进行了简述。并对目前面临需要进一步研究的问题进行简要叙述。     

高级氧化处理有机污水技术进展

综述了高级氧化技术的原理，介绍了O3／UV、H2O2／UV、O3／H2O2组合过程及非均相TiO2光催化氧化等几种典型的高级氧化技术，阐述了高级氧化技术降解有机污水的机理以及在水处理中的应用进展。指出，高级氧化过程应用领域应扩展到水体中难降解的持久性有机污染物，并应加强高级氧化过程所需新型反应器的研制，以便进一步强化废水的5降解，提高其处理效率。     

Effects of molecular weight and molecular weight distribution on creep properties of polypropylene homopolymer

The molecular weights of the industrial-grade isotactic polypropylene (i-PP) homopolymers samples were determined by the melt-state rheological method and effects of molecular weight and molecular weight distribution on solid and melt state creep properties were investigated in detail. The melt-state creep test results showed that the creep resistance of the samples increased by M_w due to the increased chain entanglements, while variations in the polydispersity index (PDI) values did not cause a considerable change in the creep strain values. Moreover, the solid-state creep test results showed that creep strain values increased by M_w and PDI due to the decreasing amount of crystalline structure in the polymer. The results also showed that the amount of crystalline segment was more effective than chain entanglements that were caused by long polymer chains on the creep resistance of the polymers. Modeling the solid-state viscoelastic structure of the samples by the Burger model revealed that the weight of the viscous strain in the total creep strain increased with M_w and PDI, which meant that the differences in the creep strain values of the samples would be more pronounced at extended periods of time.     

The molecular weight distribution of oligomers

It is shown that the relation $\text{P}{}_{\mathrm{w}}\text{P}{}_{\mathrm{n}}\text{= 2}$ or the nonuniformity U = 1 is only a limiting case for high degrees of polymerization, is no more valid for oligomers. Two new relations are derived, one including and one excluding monomers. For the oligomer part of cationically produced polystyrenes the second relation is in good agreement with experiments.