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磷酸二氢钾结晶介稳区性质研究 总被引:1,自引:0,他引:1
在磷酸二氢钾的生产中,为得到理想的晶体粒度及其分布,要求结晶在磷酸二氢钾水溶液的介稳区内进行,因此研究了不同温度、不同降温速率及不同搅拌速度下磷酸二氢钾水溶液的介稳区宽度,同时研究了铁离子杂质对磷酸二氢钾水溶液介稳区宽度的影响.结果表明:温度升高,介稳区宽度变窄;降温速率增大,介稳区宽度变宽;搅拌速度增大,介稳区宽度变窄,低温区变化幅度为2 ℃左右,高温区变化幅度小于1 ℃;铁离子的存在使介稳区宽度变宽,并得到介稳区宽度与铁离子质量分数的定量关系. 相似文献
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在混合悬浮结晶器中研究了氯化铵结晶热力学和动力学特性。以硝酸锰为添加剂,配制了质量分数为0.23%的硝酸锰水溶液,测定了氯化铵在该溶液中的溶解度及超溶解度。研究了硝酸锰对氯化铵晶体粒度分布的影响,得到了晶体变异系数。考察了过饱和度对氯化铵结晶线性生长速率和成核速率的影响,得到了成核-生长动力学方程。结果表明:介稳区宽度随温度升高而减小;添加晶种,介稳区宽度变窄。随硝酸锰溶液浓度增大,晶体变异系数逐渐降低并趋于平缓。当硝酸锰的质量分数逐渐增大到0.307%时,晶体变异系数几乎不再降低。线性生长速率和成核速率随溶液过饱和度的增大而增加,得到的动力学方程与实验数据吻合较好,有一定的工业参考价值。 相似文献
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通过静态平衡法测定七水氯化镧在水中的溶解度,分别用Apelblat经验方程和λh方程对溶解度数据进行拟合与评估。利用激光散射法测定氯化镧水溶液冷却结晶的介稳区宽度,在推导出初级成核速率基础上,通过实验分析操作参数温度、搅拌和降温速率等对氯化镧冷却结晶介稳区宽度、成核级数的影响。结果表明,两个溶解度模型均能很好地拟合七水氯化镧在水中的溶解度;氯化镧的介稳区宽度比一般无机盐的要大很多,随着降温速率的增大和搅拌速率的减小而变宽,且成核级数的大小受温度的影响, 随温度的升高而变大。 相似文献
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采用梅特勒-托利多在线结晶工作站系统地研究了磷酸二氢钾的溶解度、超溶解度、红外特性以及冷却结晶过程的影响因素。结果表明,磷酸二氢钾的介稳区在低温区较宽,高温区较窄,且在40.1 ℃下具有最宽的介稳区;磷酸二氢钾在红外光谱上具有较好的朗伯-比尔特性,其特征峰波数分布在2 152 cm-1和1 082 cm-1处;降温速率越大,其介稳区宽度也随之增大;搅拌速率越高,其介稳区宽度反而降低;pH=4.0时,结晶效果最好,粒度分布也最为均匀,晶体颗粒粒径大;Fe3+的含量增大,将会导致磷酸二氢钾的介稳区变宽,并且其含量越大,颗粒越不均匀,粒度分布较宽,因此应严格控制生产工艺中Fe3+的质量分数≤0.001%;SO42-含量的增大,会使介稳区变窄,将会导致工业上结晶不易控制,因此也需严格控制生产工艺中SO42-的含量。 相似文献
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溶液的介稳区是结晶的基础研究之一.利用静态法测定醋酸钠在水中不同温度下的溶解度,同时利用激光散射法测定醋酸钠在不同温度、搅拌速率、降温速率条件下的超溶解度,得到溶解度与超溶解度的曲线从而拟合出醋酸钠在水中溶解度和超溶解度的方程,确定介稳区范围.研究结果表明,醋酸钠的溶解度随着温度的升高而升高.在一定条件下,搅拌速率越大、温度越高、降温速率越快,介稳区宽度越窄. 相似文献
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《化工进展》2017,(9)
在实施废水零排放工程中,有机物的存在给无机盐结晶过程带来不利影响,因而有必要考察有机物添加剂对盐结晶的影响规律。本文测定了氯化钠在水以及添加蛋白胨、苯酚和庚二酸的水溶液中的溶解度和超溶解度,考察了介稳区的变化规律。结果表明,3种有机物均使氯化钠溶解度降低,且溶解度随有机物含量的增大而减小,其中庚二酸的影响最大。3种有机物的存在也同时降低了介稳区的宽度,且随有机物含量增大而减小,影响大小顺序为苯酚庚二酸蛋白胨。在饱和温度为343.15K、COD为20000mg/L的苯酚溶液中,氯化钠介稳区宽度较纯水中相比可减小65.3%,影响效果明显。介稳区随搅拌速率的增大、降温速率的减小而变窄。搅拌速率在不同有机物存在下对介稳区影响大小顺序为庚二酸蛋白胨苯酚,降温速率在不同有机物存在下对介稳区影响大小顺序为蛋白胨苯酚庚二酸。 相似文献
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针对5’-单磷酸腺苷(5’-AMP)在溶析结晶中易出现爆发结晶的问题,分别采用静态法和激光法测定了293—323 K下5’-AMP在纯水以及溶剂体积比为0.3—2.0的乙醇-水体系中的溶解度和超溶解度,以指数经验关联式建立了超溶解度关联式,并在试验条件下考察了温度、乙醇流速、pH值和搅拌速率对介稳区宽度的影响。运用中心复合设计预测了5’-AMP在本溶析结晶体系中介稳区间,并用扫描电镜观察了5’-AMP在结晶条件优化前后晶体形态的变化情况,为工业生产中提高结晶产品质量提供了理论指导。 相似文献
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介稳区宽度(MSZW)是结晶过程设计的重要参数,为了得到高纯度大颗粒的烟酸晶体,应将结晶条件控制在介稳区内。测定烟酸在293.15—323.15 K下的溶解度,并用Apelblet经验方程关联,与实验值相比有较好的拟合效果,相对偏差在0.66%以下,平均偏差为0.27%;以溶解度数据为基础,计算了烟酸的溶解热力学参数。另外,通过聚焦光速反射测量(FBRM)技术测定烟酸的介稳区宽度,研究了降温速率、搅拌速率和晶种加入量对介稳区宽度的影响,研究发现,较小的降温速率、较大的搅拌速率以及加入晶种都会使介稳区宽度变窄;适当增大晶种数目,可以有效调节介稳区。溶解度及介稳区的测定,为生产过程工艺放大以及结晶器的设计提供数据支撑。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively.
There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized.
High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without
the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of
fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to
achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic
SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve
F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender
particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing,
and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing
or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually
preserves suspension stability during freezing.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago,
IL. Tied for first place in The John A. Gordon Best Paper Competition. 相似文献
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Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae
and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted
in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures
(release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species
(Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species
to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were
exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of
separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles
from the southeastern region of the US. 相似文献
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Peter A. Edwards Grant Striemer Dean C. Webster 《Journal of Coatings Technology and Research》2005,2(7):517-527
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins.
Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol.
The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and
cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on
the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to
determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model
amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate
functional group is more reactive than a glycidyl ether group.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献
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Dongjiang Yang Yao Xu Lei Zhang Shangru Zhai Dong Wu Yuhan Sun 《Journal of Coatings Technology and Research》2006,3(2):127-131
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals. 相似文献