三种阴离子聚合物分散剂在吡虫啉颗粒表面的吸附热力学和动力学

通过振荡吸附实验研究了三种阴离子聚合物分散剂Morwet D-425、GYD-1252和LG-3在农药吡虫啉颗粒表面的吸附热力学和动力学,对比分析了三种分散剂吸附性能的差异。吸附等温线符合Langmuir和Freundlich吸附等温方程,前者拟合程度较高。由ΔG<0、ΔH<0、ΔS>0可知该吸附为自发、放热、熵增过程,高温不利于吸附进行,|ΔH|<40 kJ·mol^-1表明该吸附为物理吸附。通过对比可知Morwet D-425吸附稳定性最高,受温度影响最小;LG-3吸附稳定性最低,受温度影响最大;GYD-1252吸附稳定性介于两者之间。吸附动力学曲线最符合伪二级动力学方程,吸附过程包括颗粒外传质扩散和表面吸附两个步骤,不包括颗粒内微孔扩散。吸附速率由大到小的顺序为Morwet D-425、GYD-1252、LG-3.通过XPS测定不同温度下分散剂吸附层厚度可知Morwet D-425在吡虫啉颗粒表面的吸附致密,吸附层厚度较低但随温度升高变化很小;GYD-1252和LG-3在吡虫啉颗粒表面吸附疏松,低温下吸附层厚度较高但随温度升高明显降低。     

2种聚羧酸盐类分散剂在氟吡菌酰胺颗粒表面的吸附性能

[目的]通过研究聚羧酸盐类分散剂在氟吡菌酰胺颗粒表面的吸附性能,为氟吡菌酰胺悬浮剂的开发提供理论依据。[方法]利用傅里叶红外光谱仪(FTIR)和紫外-可见分光光度计(UV)分析了氟吡菌酰胺与2种聚羧酸盐类分散剂Atlox Metasperse 550S (550S)和Agrilan 700(A700)之间的吸附作用力以及吸附量的影响因素。[结果]2种分散剂与氟吡菌酰胺颗粒间的吸附为物理吸附,主要的吸附作用力为范德华力;在298、308、318 K的试验温度下,达到饱和吸附量90%(或95%、99%)时分散剂550S和A700的质量浓度分别约为20 000、25 000 mg/L,吸附量随着温度的升高而降低;吸附等温线模型均符合Langmuir模型;在298 K的试验温度下,分散剂550S和A700在氟吡菌酰胺颗粒表面饱和吸附量达到90%(或95%、99%)时的时间分别为30、70 min左右,吸附动力学均符合准一级动力学模型(R20.94),拟合饱和吸附量与试验值相近;在试验质量浓度范围内随着NaCl质量浓度的增加,分散剂在氟吡菌酰胺颗粒表面的吸附量增加,当NaCl的质量浓度为10 g/L时吸附量达到限值;随着pH值的增加,吸附量表现出下降的趋势,当pH值小于6时,2种分散剂在氟吡菌酰胺颗粒表面的吸附量较大。[结论]分散剂550S和A700加工氟吡菌酰胺悬浮剂时为充分发挥分散剂效果,体系酸碱度要保持中性或弱碱性,适当添加NaCl保持低温提高悬浮剂的稳定性。推荐20%氟吡菌酰胺悬浮液添加分散剂550S和A700的量分别为2%和2.5%。     

梳型聚羧酸盐分散剂的合成及其在吡虫啉水悬浮剂中的应用

以马来酸酐(MA)和聚乙二醇200 (PEG200)为原料,通过酯化反应制得大分子马来酸聚乙二醇酯(MAPEG),再与丙烯酸(AA)、甲基丙烯酸甲酯(MMA)通过自由基聚合反应制得3种梳型聚羧酸盐分散剂,研究了不同单体比例的聚合物分散剂在600 g/L吡虫啉水悬浮剂中的流点、粘度和Zeta电位. 结果表明,当单体摩尔比MAPEG:AA:MMA为1:8:2、共聚物分散剂添加量为6%(w)时,悬浮液粘度最小,为600 MPa×s,热贮前后悬浮率分别为93.7%±0.22%和92.3%±0.12%,粒径分别为3.26和3.88 mm,分散效果与市售同类产品亨斯迈2500相当.     

新型农药分散剂聚羧酸盐合成的国内外研究进展

综述了新型农药分散剂聚羧酸盐的概况.分别讨论了作为分散剂的聚羧酸盐中丙烯酸均聚物,丙烯酸与第二单体二元共聚物,丙烯酸与第二、第三单体三元共聚物,以及其他聚羧酸盐类的合成方法.介绍了聚羧酸盐的表征、标准和质量指标.阐述了聚羧酸盐的毒性和环境保护.     

苯乙烯-甲基丙烯酸钠共聚物在吡虫啉颗粒表面的吸附特性

通过溶液聚合合成一系列苯乙烯-甲基丙烯酸钠共聚物分散剂.研究了不同单体摩尔比对其产率和在吡虫啉颗粒表面吸附性能的影响,结果表明当两种单体摩尔比为0.8时分散剂的产率和吸附性能相对最优.通过振荡吸附实验研究了最优分散剂在吡虫啉颗粒表面的吸附动力学、等温线和热力学,由XPS近似计算不同温度下分散剂的吸附层厚度.结果表明:吸附动力学符合伪二级动力学方程;吸附等温线符合Langmuir模型;吸附热力学表明该吸附为自发、放热、熵增过程,高温不利于吸附进行;DH_ad < 40 kJ·mol^-1表明该吸附过程为物理吸附;吸附层厚度随温度升高而降低.通过与其他商品化分散剂对比可知该共聚物适合作为分散剂用于吡虫啉的水基化剂型.     

乳液聚合法合成农用聚羧酸盐分散剂

以甲基丙烯酸、含有聚氧乙烯或聚氧丙烯的长链不饱和大分子单体和苯乙烯为单体,采用乳液聚合法合成了农用聚羧酸盐分散剂。通过正交试验确定了合成聚羧酸分散剂的最佳原料配比及合成条件,并将该分散剂应用于农药悬浮剂中。结果表明:所配制悬浮剂的悬浮率在90%以上;该方法合成的聚羧酸盐分散剂具有优良的分散性能,是一种高效的农用分散剂。     

羧酸盐磺酸盐共聚物分散剂合成及其分散性能

合成了丙烯酸(AA)-苯乙烯磺酸钠(SSS)-顺丁烯二酸酐(MA)三元共聚物钠盐分散剂,研究了其对无机物BaSO4和有机物农药吡虫啉的分散效果,并对BaSO4悬浮颗粒的形貌、晶型结构及粒径分布进行了表征.结果表明,当单体质量比AA:SSS:MA=20:4.5:2.0、反应温度70℃、引发剂占单体总质量7.5%、聚合时间1.5h时,制备的最优化分散剂M17在20℃的中性体系中对BaSO4的悬浮率达98.78%,平均粒径为0.454μm,对70%吡虫啉水分散粒剂的悬浮率为84.40%,分散效果与罗地亚T36相当.     

600g/L吡虫啉悬浮剂中分散剂的开发

针对吡虫啉原药结构,合成了一系列聚羧酸盐高分子分散剂。采用该系列分散剂对600 g/L吡虫啉悬浮剂配方进行研究,最佳配方为:48%吡虫啉、4%PC-095-20、3%乙二醇、0.1%黄原胶,0.3%消泡剂,水补足至100%。制得的悬浮剂悬浮率高,分解率低,热贮和低温稳定性合格。     

聚羧酸类分散剂对超细CaCO3粉体的吸附行为研究

测定了聚羧酸类分散剂SDA-30与超细CaCO3的吸附动力学曲线.考查了粉体性质、平衡温度及悬浮液pH值对吸附量的影响.探讨了聚羧酸类分散剂的电离性质对其在CaCO3表面吸附构型的影响.测定了分散剂作用前后的悬浮液电性质.结果表明该分散剂在CaCO3粉体表面的吸附属于langumuir型单分子层吸附;SDA-30在CaCO3表面的饱和吸附量随粉体目数的增加、温度的降低、pH值的减少而增大;SDA-30的分散稳定作用主要取决于静电斥力.     

煤对CWM分散剂吸附性能的研究

本文选择三种具有代表性ＣＷＭ分散剂，借助ＦＴ－ＩＲ和ＸＰＳ等现代实验手段对分散剂在煤表面的吸附性能进行了分析，揭示了ＣＷＭ分散剂吸附特征，为从组成和结构上选取优良分散剂提供实验依据。     

萘磺酸盐分散剂在不同晶型吡唑醚菌酯颗粒表面吸附性能

通过X射线衍射仪（XRD）、差示扫描量热仪（DSC）、紫外光谱（UV）、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）和扫描电子显微镜（SEM）测试,研究了萘磺酸盐分散剂在两种晶型吡唑醚菌酯颗粒表面的吸附性能。两种晶型吡唑醚菌酯吸附萘磺酸盐分散剂后,晶型未发生改变;两种晶型吡唑醚菌酯吸附动力学均符合伪二级动力学方程,晶型Ⅱ E_a＝16.04 kJ·mol^-1,晶型Ⅳ E_a＝12.42 kJ·mol^-1,均为物理吸附;吡唑醚菌酯晶型Ⅱ、晶型Ⅳ吸附等温线均符合Langmuir模型,晶型Ⅱ的吸附焓变H_ad为20.64 kJ·mol^-1,吸附过程为吸热过程,温度升高有利于萘磺酸盐甲醛缩合物（D425）在晶型Ⅱ颗粒表面的吸附;晶型Ⅳ的吸附焓变H_ad为-15.26 kJ·mol^-1,吸附过程为放热过程,温度升高不利于D425在晶型Ⅳ颗粒表面的吸附。     

聚羧酸减水剂在水泥颗粒表面的吸附行为

合成一系列聚羧酸减水剂,探讨不同单体摩尔比对其吸附性能的影响。结果表明,当n(烯丙醇聚氧乙烯醚)∶n(2-丙烯酰胺-2-甲基丙磺酸钠)∶n(丙烯酸)∶n(马来酸酐)=1∶0.14∶3.6∶2.6时,产物吸附性能最优。并利用总有机碳分析技术,研究了不同温度、不同浓度下最优产物在水泥颗粒表面的吸附动力学和热力学。动力学研究结果表明：聚羧酸在水泥颗粒表面的吸附过程符合Lagergren吸附速率方程,吸附速率常数k=0.01594 min-1(30℃),表观活化能Ea=17.9647 kJ·mol-1。热力学研究结果表明：随温度升高,聚羧酸在水泥颗粒表面的吸附量增大;求得吸附热力学参数分别为ΔHad=-24.788 kJ·mol-1,ΔSad=0.050 kJ·mol-1·K-1,ΔGad=-39.886 kJ·mol-1(30℃),可知该吸附过程是自发的放热反应。理论上温度升高对吸附不利,但因放出的热量促进水泥水化,导致聚羧酸分子容易掺杂到水化产物中,从而使更多聚羧酸吸附到水泥颗粒表面,令其吸附量反而增大。     

色素炭黑润湿分散剂的选择

通过几个平行实验,对比了不同种类的润湿分散剂对色素炭黑的润湿分散效果、储存稳定性以及防浮色发花性,从中筛选出效果较好的分散剂。并从高分子吸附形态、高分子化合物浓度、溶剂、酸/碱基、粒子表面形态等对分散剂在颜料表面的吸附的影响进行了分析。结果表明,用带有颜料亲和基团的高分子量嵌段封闭共聚物和不饱和多元羧酸的多元胺聚酰胺结构的炭黑润湿分散剂研磨炭黑色浆效率高,细度下降快,研磨的色浆储存性好,黑度高,防浮色发花性好,在炭黑润湿分散方面取得了良好的效果。     

Adsorption of anionic amphiphilic polyelectrolytes onto amino-terminated solid surfaces

The adsorption behavior of several amphiphilic polyelectrolytes of poly(maleic anhydride-alt-styrene) functionalized with naphthyl and phenyl groups, onto amino-terminated silicon wafer has been studied by means of null- ellipsometry, atomic force microscopy (AFM) and contact angle measurements. The maximum of adsorption, Γ_plateau, varies with the ionic strength, the polyelectrolyte structure and the chain length. Values of Γ_plateau obtained at low and high ionic strengths indicate that the adsorption follows the “screening-reduced adsorption” regime. Large aggregates were detected in solution by means of dynamic light scattering and fluorescence measurements. However, AFM indicated the formation of smooth layers and the absence of aggregates. A model based on a two-step adsorption behavior was proposed. In the first one, isolated chains in equilibrium with the aggregates in solution adsorbed onto amino-terminated surface. The adsorption is driven by electrostatic interaction between protonated surface and carboxylate groups. This first layer exposes naphtyl or phenyl groups to the solution. The second layer adsorption is now driven by hydrophobic interaction between surface and chains and exposes carboxylate groups to the medium, which repel the forthcoming chain by electrostatic repulsion. Upon drying some hydrophobic naphtyl or phenyl groups might be oriented to the air, as revealed by contact angle measurements. Such amphiphilic polyelectrolyte layers worked well for the building-up of multilayers with chitosan.     

Adsorption of polyethylene from solution onto starch film surfaces

We prepared starch films by jet‐cooking aqueous dispersions of high‐amylose starch and then allowing the jet‐cooked dispersions to air‐dry on Teflon surfaces. When the starch films were immersed in 1% solutions of polyethylene (PE) in 1‐dodecanol, dodecane, and xylene at 120°C and the solutions were allowed to slowly cool, PE precipitated from the solutions and adsorbed onto the starch film surfaces. Fourier transform infrared spectroscopy was used to estimate the micrograms of PE adsorbed per square centimeter of starch film. PE was preferentially adsorbed onto the film side that was in contact with the Teflon surface during drying. The amount of PE adsorbed ranged from about 8 to 45 μg/cm² and depended upon the solvent used and the final temperature of the cooled solution. Scanning electron microscopy of the starch film surfaces showed discontinuous networks of adsorbed PE on the Teflon side and widely spaced nodules of adsorbed PE on the air side. NMR analysis showed that the PE adsorbed onto the starch surface was more linear and/or had a higher molecular weight than the starting PE. Possible reasons for the selective adsorption of PE onto the Teflon side of the starch film surface are discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adsorption of bovine serum albumin onto glass powder surfaces coated with polyvinyl alcohol

The adsorption of bovine serum albumin (BSA) was carried out onto polyvinyl alcohol–coated glass powder surfaces. The adsorbed amount was about four times more than that on uncoated glass. The kinetics of the adsorption process was followed colorimetrically, and kinetic parameters, such as adsorption coefficient, rate constants for adsorption and desorption, diffusion constant, and penetration rate constant, were evaluated. The effects of experimental conditions, such as pH, presence of salts, addition of aliphatic alcohols, and variation in the dielectric constant of the medium, on the amount of adsorbed BSA were investigated. The effect of temperature on adsorption was also studied, and several thermodynamic parameters, such as standard free energy change (ΔG°), heat of reaction (ΔH°), and entropy change (ΔS°), were evaluated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 933–940, 2000     

碱解-微电解工艺对吡虫啉农药生产废水预处理的研究

吡虫啉农药生产废水是一种典型的高浓度难降解有机废水,可生化性差,需采用物化法作为其预处理手段.实验采用碱解-微电解作为吡虫啉农药生产废水的主要预处理工艺,能有效地降低废水中有机物浓度,使预处理出水的可生化性大大提高,保证其后续生化处理的有效进行.实验表明,碱解最佳条件:温度70 ℃,pH 13,反应时间2 h;微电解最佳条件:pH 3～4,停留时间3 h.预处理出水的COD总去除率为65%左右,色度的去除率达90%以上,m(BOD5):m(COD)提高到0.25以上,可生化性大大提高.