Hygroscopic growth of nucleation-mode acidic sulfate particles

The hygroscopic growth factors of acidic sulfate nanoparticles relevant to atmospheric new-particle formation and growth were measured using a tandem nano-differential mobility analyzer (TnDMA). The dry diameters of the particles ranged from 5.5 to 53.2 nm. The growth factors progressively decreased for smaller dry particle diameters. For the largest particles, a model including the Kelvin effect and assuming fully acidic particles agreed well with the observed hygroscopic growth factors. For particles having dry diameters smaller than 36.1 nm, an expanded model based on a progressively increasing extent of neutralization for smaller particles and for higher relative humidity values explained the observations. Partial neutralization occurred because of adventitious ${\mathrm{NH}}_3$ in the experimental setup and was most significant for the lowest ${\mathrm{H}}_2{\mathrm{SO}}_4$ mass loadings, corresponding to the smallest nanoparticles. The extent of neutralization reached as high as 0.50 for the smallest particles at 80% relative humidity. Alternative explanations such as inaccuracies or nanosize effects in the density or the surface tension of the particles could not explain the observations. These results show that the hygroscopic behavior of acidic sulfate nanoparticles is more sensitive to the extent of neutralization than to the other considered possible nanosize effects, at least for dry particle diameters as small as 5.5 nm.     

The effect of carboxylic acids and phosphate salts additives on the properties of chondroitin sulfate calcium phosphate cements

The use of liquid phase additives is a strategy to improve the physicochemical, mechanical, and biological properties of calcium phosphate cements. In this study, TTCP and α-TCP particles were synthesized using the solid-state reaction method. Apatite cements were prepared by mixing TTCP/DCPD/α-TCP powders and liquid phases containing chondroitin sulfate with various additives of carboxylic acids and phosphate salts. The formation of hydroxyapatite and consumption of raw materials as well as the acceleration and deceleration periods through cementation process were investigated by XRD and DSC experiments, respectively. In addition, the morphology, setting time, porosity, compressive strength, degradation, in-vitro bioactivity and cytotoxicity were studied. The results showed that the approximate amount of hydroxyapatite resulting from the cementation process was divergent in the presence of liquid phase additives. The use of phosphate salt additives presented better results compared to carboxylic acid ones regarding hydroxyapatite cement product formation, compressive strength, hardening, setting, and cytotoxicity. All cements showed, generally a similar tendency to form dense hydroxyapatite on their outer surfaces through immersion in the simulated body fluid. The cement containing Na₂HPO₄ salt exhibited the lowest cytotoxicity and highest strength. The ALP assay and the morphological behavior of MG63 cells indicated the good activity and proper cell adhesion of this cement.     

Growth of Aitken mode ammonium sulfate particles by α-pinene ozonolysis

The fraction of Aitken mode particles that grow sufficiently large to act as cloud condensation nuclei is an important factor in understanding the climate impact of atmospheric particles. Elucidating the rate of particle growth in this size range requires a detailed understanding of the mechanisms by which these particles grow. Here, a flow tube reactor is described, characterized and then used to study growth of ammonium sulfate seed particles in the Aitken mode size range by α-pinene ozonolysis under dry conditions (10% RH). When size-selected particles starting at 40, 60, or 80?nm diameter were exposed to α-pinene (11?ppbv) and ozone (five separate mixing ratios between 30 and 250?ppbv), particle growth was found to depend on the amount of α-pinene reacted and the condensation sink, but not directly dependent on the initial seed particle diameter. The observed dependencies are consistent with a condensational growth mechanism, which is not surprising since the dry conditions of the experiment minimized the probability of multiphase chemistry within the seed particles. Combining the measured particle growth with a kinetic model gave a molar yield of 13% for condensable organic molecules produced by the ozonolysis reaction. This value is somewhat higher than previously reported molar yields of highly oxidized molecules (HOMs) measured in the gas phase with chemical ionization mass spectrometry, which are in the 3–7% range. The relationship between molar yields determined from gas phase and particle phase measurements is discussed.

Copyright © 2019 American Association for Aerosol Research     

Direct observation of water uptake and release in individual submicrometer sized ammonium sulfate and ammonium sulfate/adipic acid particles using X-ray microspectroscopy

Scanning transmission X-ray microscopy (STXM), a microscopy method which allows imaging with a spatial resolution of 40 nm, and X-ray absorption spectroscopy were used to follow in situ the water uptake and release in submicrometer sized particles on a substrate enclosed in a microreactor. Oxygen K-edge near edge X-ray absorption fine structure (NEXAFS) spectra from supported ammonium sulfate particles in their dry salt, saturated solution and supersaturated solution states were obtained for the first time. The variations at the oxygen edge were related to the water content as a function of relative humidity (RH), consistent with mass growth measurements done on larger samples or suspended particle ensembles. Investigations on morphological changes upon water uptake were performed in mixed ammonium sulfate-adipic acid particles using STXM images and NEXAFS spectra taken at the oxygen and the carbon absorption edges, confirming the two phase structure suspected from previous hygroscopicity studies, where adipic acid forms a separate phase of complex morphology partially enclosed by the ammonium sulfate solution at high RH. This example emphasizes the combination of chemical resolution provided via NEXAFS, spatial resolution via STXM and the in situ capability provided by the novel microreactor to obtain information about the microstructure of mixed organic/inorganic particles under close to ambient conditions.     

Hygroscopic properties of potassium-halide nanoparticles

The hygroscopic properties of KBr, KCl, and KI nanoparticles having diameters from 8 to 60 nm were measured using a tandem Differential Mobility Analyzer. In all cases, the deliquescence and efflorescence relative humidity values increased with decreasing particle diameter. The associated growth factors also decreased with decreasing particle diameter, in agreement with predictions by Köhler theory. Overall, the theoretically predicted growth factors agreed well with the measurements, i.e., within ±3% uncertainty. For KCl particles having sizes down to 15 nm, however, a dynamic shape factor of 1.08, corresponding to non-spherical crystalline particles prior deliquescence, was inferred for agreement between measurements and theory. By comparison, KBr and KI within the same size range warranted shape factors of unity, equivalent to a sphere. These results contribute to an understanding of nanosize behavior widely relevant to material sciences as well as atmospheric aerosol particles over the oceans.     

硫酸铵溶液对混凝土碳化及力学性能的影响研究

将混凝土标准试块分组放入清水和浓度分别为2.5%和5%的硫酸铵溶液中,浸泡28 d后取出烘干,在实验室进行快速碳化实验、回弹实验和抗压强度实验,分析研究硫酸铵溶液浓度对混凝土碳化及抗压强度的影响规律。制定了2.5%和5%两种浓度硫酸铵溶液环境下混凝土专用测强曲线,误差范围满足规范要求,可供实际工程参考。     

硫酸铵溶液对混凝土碳化及力学性能的影响研究

将混凝土标准试块分组放入清水和浓度分别为2.5%和5%的硫酸铵溶液中,浸泡28 d后取出烘干,在实验室进行快速碳化实验、回弹实验和抗压强度实验,分析研究硫酸铵溶液浓度对混凝土碳化及抗压强度的影响规律。制定了2.5%和5%两种浓度硫酸铵溶液环境下混凝土专用测强曲线,误差范围满足规范要求,可供实际工程参考。     

N,N-二甲基甲酰胺-硫酸二甲酯对羧酸酯化反应的研究

N,N-二甲基甲酰胺二甲基缩醛(简称 DMFDMA)是一种在有机合成中应用很广的多 功能试剂,该试剂以其反应条件温和,产率高,快 速及简便的后处理等优点,已广泛用于多种化合 物的合成[1～4].     

Role of oleic acid coating in the heterogeneous uptake of dimethylamine by ammonium sulfate particles

Reactive uptake by ammonium (NH₄⁺) salts is one of the major pathways for the gas-to-particle partitioning of alkyl amines. Recent studies using particles of individual ammonium salts and mixtures with hydrophilic organics have revealed that the degree of amine uptake depends on the phase state of ammonium salts, the particulate water contents and particle viscosity. The role of hydrophobic organic compounds, another important category of particulate organics commonly detected in the ambient atmosphere, in amine uptake remains unknown. Here we report the uptake of dimethylamine (DMA) by ammonium sulfate (AS) particles coated with fresh or ozone-aged bulk oleic acid (OA) at 60%, 30%, and <5% relative humidities (RHs) using an electrodynamic balance coupled with Raman spectroscopy. OA and DMA were selected to represent hydrophobic organics and alkyl amines, respectively. Over 74% of the original NH₄⁺ ions were displaced due to DMA uptake, except those conditioned at <5% RH. On the other hand, the fresh or aged bulk OA coating retarded DMA uptake by preventing the particle surface from effectively accommodating gaseous DMA molecules. Judging from the estimated DMA uptake coefficients, the retardation gradually intensified as the weight percentage of coating increased before leveling off, likely when the particle surface was completely covered by fresh or aged bulk OA. We propose that the accommodation of DMA on the particle coating is the rate-limiting step of DMA uptake. Intensive aging of the OA coating had little effect on the equilibrium particle-phase compositions but retarded DMA uptake.

© 2017 American Association for Aerosol Research     

硫铵装置技术升级改造

为满足《炼焦化学工业污染物排放标准》(GB 16171—2012)中大气污染物排放要求,对硫铵生产装置生产系统切换升级改造和尾气洗涤净化装置技术改造,改造后硫铵尾气氨、颗粒物排放指标均低于新标准浓度限值。     

Monoethoxylation of hindered carboxylic acids

Polyethoxylates of unhindered fatty acids are well known as surface active agents. The monoethoxylates of these acids, however, are difficult to prepare in good yields. It has now been demonstrated that monoethoxylates of hindered aliphatic acids can be prepared in high selectivity and conversion. Experimental conditions are reported which overcome serious side reactions prevalent with unhindered acids. Presented at the 156th American Chemical Society National Meeting.     

硫酸铵、羟基乙酸混合液中各组分的定量分析方法研究

硫酸铵、羟基乙酸(GA)混合溶液中各组分定量分析时均存在另一组分的严重干扰。在甲醛法测定硫酸铵含量、酸碱滴定法测定羟基乙酸含量基础上,引入乙酰丙酮分光光度法,改进并建立了混合溶液中各组分定量分析方法。探讨了检测波长、羟基乙酸浓度、乙醇浓度、恒温时间、反应温度、p H值对3,5-二乙酰基-1,4-二氢二甲基吡啶(DDL)溶液吸光度的影响。该方法的适宜条件为:p H=5~7,ω(GA)90%,60℃恒温15 min,测定波长414 nm。线性方程Ar=0.242 5 C+0.004 0,线性范围0.05~4.00μg/m L,R2=0.999 9。方法测硫酸铵含量RSD1.5%,羟基乙酸含量RSD1.8%。此分析方法快捷、简便、灵敏、准确。     

硫酸铵的应用研究进展

硫酸铵是基础科学研究和工业生产中常用的化学试剂,在促进社会经济快速发展过程中起着举足轻重的作用。本文重点介绍了硫酸铵在矿石浮选、金属回收等领域中的作用和应用情况,阐明了其应用的原理及研究进展,并简要分析了其优缺点。     

Solid state reaction of bifunctional bicyclo orthoesters and carboxylic acids and their metal adhesive properties

Five kinds of novel bifunctional bicyclo orthoesters (BOEs) were synthesized and copolymerized with multi-functional carboxylic acids, having plural carboxyl and hydroxyl groups, to develop functional materials usable as non-volatile adhesives. In a solid-state reaction of BOEs with the carboxylic acids, mechanical mixing converted the BOE moiety to a corresponding hydrolyzed form via ring-opening and isomerization reactions. The solid-state reaction, requiring moisture and mechanical stress, was accelerated by the higher reactivity given by the α-hydroxyl group in the acids. Superior adhesive bonding to the Ni-Cr alloyed metal substrate was achieved via a heating process at 150 °C, and high average tensile strengths of ∼80 MPa were obtained by using mixtures of BOEs and dl-tartaric acid. This highly adhesive property was achieved not only by polycondensation of BOE-hydrolyzates and the carboxylic acids, but also by polyaddition of BOEs and the carboxylic acids.     

Liquid-crystalline behaviour of some carboxylic acids

Summary A series of 4--carboxyalkoxyphenyl-4-methoxybenzoates 2 has been prepared. Compounds with a spacer length of n=3 and n=5 show liquid crystalline behaviour. The products were characterized by IR and ¹HNMR-spectroscopy, mass spectrometry, optical microscopy and DSC-measurements. The compounds are potentially useful as side-groups in liquid-crystalline polymers.     

磷石膏和碳酸氢铵制备硫铵复合肥工艺研究

利用磷石膏和碳酸氢铵制备市场价值较高的硫铵复合肥,探讨了磷石膏和碳酸氢铵体系的反应历程,研究了反应温度、反应时间、反应介质体积和质量分数对反应产物硫铵质量分数的影响。结果表明:当反应温度为45℃,反应时间为2h,反应介质体积和质量分数分别为180mL和10%时,反应产物硫铵的质量分数最高,约为43.72%。利用BK-POL型偏光显微镜观察产物硫铵溶液的自然结晶体,观察的结果为菱形柱状结晶。     

1,3-二氧环辛烷-2-羧酸类三环化合物的合成及其除草活性

二苯并1,3-二氧环辛烷-2-羧酸类三环化合物(见通式Ⅰ)(dibenzodioxocincarboxylic acid简称DBZ)的应用研究早期主要在医药方面(1977).Dow化学公司首先报道了此类化合物作为除草剂在农业上的应用(US 4976770 A,1990).1994年罗门哈斯公司的Lori Spangler博士注意到这类化合物结构新颖、公开专利较少(不超过10篇),开始了先导优化工作.沈阳院首先合成出专利中化合物(Ⅱ),经生测表明,化合物(Ⅱ)作用方式较慢、苗后活性高于苗前、杀草谱广、活性高(150g／ha),符合当前除草剂的发展方向.因此,双方成立了DBZ项目小组,其中包括合成人员、生测人…     

电解锰生产用硫酸锰、镁、铵复盐体系结晶的研究

在电解锰浸出液中,Mn⁽²⁺⁾、Mg(2+)、Mg⁽²⁺⁾、NH(2+)、NH⁺_4初始浓度分别为28,20,30 g/L时,研究结晶温度、蒸发瓶转速、结晶时间、有无晶种对复盐体系结晶的影响。结果表明,随着结晶温度的提高,锰、镁、铵结晶率呈快速上升趋势;随着转速和结晶时间的提高,锰、镁、铵结晶率整体呈缓慢上升趋势;相较无晶种添加,添加8%晶种时,可小幅提高体系结晶率。复盐体系锰、镁、铵结晶的最佳工艺条件为:结晶温度为55℃,转速为90 r/min,结晶时间为60 min,添加8%晶种,此时,复盐体系锰、镁、铵结晶率分别为68.05%,97.59%,94.81%,效果较好。     

Solution properties of mixed surfactant system sodium dodecyl sulfate and alkyl polyoxyethylene ether system

The effect of oxyethylene groups in a nonionic surfactant on the solution properties of anionicnonionic systems is described; these systems are sodium dodecyl sulfate (SDS)—hexadecyl polyoxyethylene ethers (C₁₆POE_n, where n=10, 20, 30 and 40). The degree of ionic dissociation of the mixed micelles decreases with increasing numbers of oxyethylene groups in the nonionic surfactant. As polyoxyethylene chain lengths increase, the electrical conductivities of the mixed surfactant solutions decrease, in spite of the decrease in activation energy for conduction. The radius of the mixed micelle with the electric double layer is larger for a nonionic surfactant having a shorter polyoxyethylene chain length than for one having a long polyoxyethylene chain. This may be attributed to the fact that the mixed micelle is formed more easily by a nonionic surfactant with a shorter polyoxyethylene chain length than by one with a longer chain.