结晶添加剂对硫酸钾结晶过程影响研究

本文研究了NH4^ ,K^ ,Cl^-,SO4^2-离子的混合体系中K2SO4晶习，晶形特性，考查了不同结昌添加剂对K2SO4结晶的影响，探讨了各种离子对硫酸钾在混合体系中结晶过程影响机制，试验结果表明，Mg^2 和十二烷基苯磺酸钠有促进K2SO4晶体结晶作用，而Fe^3 ,Al^3＋对结晶有一定的抑制作用。     

四元体系K+∥Cl-、SO42-、B4O72--H2O 298K相平衡的理论计算

采用298 K时三元子体系K+∥SO42-、B4O72--H2O 298 K的相平衡溶解度,应用多元线性回归的方法拟合了该体系中Pitzer方程所需盐的混合离子作用参数ΨK,B4O7,SO4;并且运用Pitzer方程对298 K时四元体系K+∥Cl-、SO42-、B4O72--H2O溶解度数据进行了理论计算。根据计算出的溶解度数据绘制出四元体系计算相图,从相图中得知,该四元体系有一个共饱点,三条单变曲线,及三个结晶区平衡固相。研究结果发现,模拟计算值与实测值基本吻合。     

四元体系K~＋∥Cl~-、SO_4~（2-）、B_4O_7~（2-）-H_2O 298K相平衡的理论计算

采用298 K时三元子体系K＋∥SO42-、B4O72--H2O 298 K的相平衡溶解度,应用多元线性回归的方法拟合了该体系中Pitzer方程所需盐的混合离子作用参数ΨK,B4O7,SO4;并且运用Pitzer方程对298 K时四元体系K＋∥Cl-、SO42-、B4O72--H2O溶解度数据进行了理论计算。根据计算出的溶解度数据绘制出四元体系计算相图,从相图中得知,该四元体系有一个共饱点,三条单变曲线,及三个结晶区平衡固相。研究结果发现,模拟计算值与实测值基本吻合。     

混合表面活性剂对氯化钠晶体生长的控制研究

研究了K+,Na+//Cl-,SO2-4体系中氯化钠蒸发结晶过程中混合表面活性剂的加入对晶体的成核及生长的显著影响。控制混合表面活性剂组份与用量在极短时间内得到晶形完美的氯化钠大晶体(4mm～6mm),解决了因为结晶细碎造成的堵塞管道及设备结垢问题,采用自然循环式蒸发器代替强制循环类蒸发器,能源消耗降低了70%,从而降低生产成本,提高了氯化钠的质量,大大降低了K+的循环损失。     

Pitzer混合参数对CsCl—Cs2SO4—H2O体系25℃时溶解度预测的影响

利用Pitzer混合参数,计算了CsCl-Cs2SO4-H2O体系25℃时的溶解度以及两离子作用参数θClSO4和三离子作用参数ΨClSO4各以±10%变动时,CsCl-Cs2SO4-H2O三元体系25℃溶解度的变化。计算的结果表明,θClSO4和ΨClSO4对CsCl、Cs2SO4的溶解度有影响。两离子混合作用不变,三离子混合作用增加或减小时,溶解度的变化最小。但当两离子与三离子混合作用同时增加或减小时,溶解度的变化最大。从定量的角度说明了θClSO4和ΨClSO4对体系性质的影响和电解质溶液的相互作用。     

Li2SO4-Na2SO4-H2O三元体系308.15K介稳相平衡研究

采用等温蒸发法研究了Li2SO4-Na2SO4-H2O体系308.15K介稳相平衡及平衡液相物化性质(密度、电导率、折光率、粘度),根据实验数据绘制了相应的介稳相图及物化性质组成图.研究发现:该介稳体系中有2种复盐,即Db1(Li2SO4·3Na2SO4·12H2O)和Db2(Li2SO4·Na2SO4)形成,其介稳相图中有三个共饱点、4条溶解度曲线和4个结晶相区.     

K2B4O7-K2SO4-KCl-H2O四元体系288 K相平衡研究

采用等温溶解平衡法研究了四元体系K2B4O7-K2SO4-KCl-H2O在288 K的相平衡及平衡液相,测定了平衡液相的溶解度及密度.研究结果表明该四元体系为简单共饱和型,无复盐及固溶体形成.根据实验数据绘制了相应的相图.相图中有一个共饱点E,三条单变曲线E1E,E2E和E3E;三个结晶区平衡固相分别为:K2B4O7·4H2O,K2SO4和KCl.实验结果表明KCl对K2B4O7·4H2O和K2SO4有盐析作用,并简要讨论了密度变化规律.     

K2B4O7-K2SO4-KCl-H2O四元体系288K相平衡研究

采用等温溶解平衡法研究了四元体系K2B4O7-K2SO4-KCl-H2O在288K的相平衡及平衡液相,测定了平衡液相的溶解度及密度。研究结果表明该四元体系为简单共饱和型,无复盐及固溶体形成。根据实验数据绘制了相应的相图。相图中有一个共饱点E,三条单变曲线E1E,E2E和E3E4三个结晶区平衡固相分别为：K2B4O7·4H20,K2SO4和KCl。实验结果表明KCl对K2B4O7·4H2O和K2SO4有盐析作用,并简要讨论了密度变化规律。     

硫酸钠镁与氯化钾复分解制取硫酸钾相图分析

文章借助K2 + 2 、Na2 + 2 ,Mg2 + ∥Cl2 -2 ,SO2 -4-H2 O和K2 + 2 ,Na2 + 2 ∥Cl2 -2 ,SO2 -4-H2 O五元及四元体系水溶液相图 ,对硫酸钠镁与氯化钾复分解制取K2 SO4进行了详尽分析和计算。文章列出了工艺原则流程图和工艺物料流量表     

Mg2+,K+//Cl-,SO2-4-H2O体系硫酸钾结晶动力学研究

文章依据硫酸镁转化法制取硫酸钾相图,配制25℃下Mg2+,K+∥Cl-,SO2-4-H2O体系硫酸钾饱和溶液,用结晶槽法研究了该体系溶液在不同过饱和度下,硫酸钾晶体的线生长速率.硫酸钾结晶动力学实验结果表明,所研究溶液体系硫酸钾晶体生长由表面反应过程控制.     

盐湖卤水提锂过程中析盐规律的研究

以Na^ ，K^ ，Mg^2 /／Cl^-，SO4^2-——H2O五元交互体系相图分析和试验，对青海某盐湖卤水提锂过程的自然蒸发阶段的蒸发析盐规律进行研究。蒸发过程中，使镁离子以镁复盐及镁的水合盐的形式，分阶段结晶析出加以分离，获得镁锂比低，锂离子浓度高的富锂卤水。同时副产氯化钠，钾盐，镁盐等有价值的副产品．使提锂成本降低，资源利用率提高。     

Solid solutions between CrO4- and SO4-ettringite Ca6(Al(OH)6)2[(CrO4)x(SO4)(1-x)]3*26 H2O

Chromate is a toxic contaminant of potential concern, as it is quite soluble in the alkaline pH range and could be released to the environment. In cementitous systems, CrO4(2?) is thought to be incorporated as a solid solution with SO4(2?) in ettringite. The formation of a solid solution (SS) could lower the soluble CrO4(2?) concentrations. Ettringite containing SO4(2?) or CrO4(2?) and mixtures thereof have been synthesized. The resulting solids and their solubility after an equilibration time of 3 months have been characterized. For CrO4-ettringite at 25 °C, a solubility product log K(S0) of ?40.2 ± 0.4 was calculated: log K(CrO4?ettringite) = 6log{Ca2+} + 2log{Al(OH)4(?)} + 3log{CrO4(2?)} + 4log{OH?} + 26log{H2O}. X-ray diffraction and the analysis of the solution indicated the formation of a regular solid solution between SO4- and CrO4-ettringite with a miscibility gap between 0.4 ≤ XCrO4 ≤ 0.6. The miscibility gap of the SO4- and CrO4-ettringite solid solution could be reproduced with a dimensionless Guggenheim fitting parameter (a0) of 2.03. The presence of a solid solution between SO4- and CrO4-ettringite results in a stabilization of the solids compared to the pure ettringites and thus in an increased uptake of CrO4(2?) in cementitious systems.     

25℃Na~+,K~+∥Cl~-,SO_4~(2-)-H_3BO_3-H_2O体系相平衡研究

实验测定了２５℃Ｎａ＋,Ｋ＋∥Ｃｌ－,ＳＯ２－４－Ｈ３ＢＯ３－Ｈ２Ｏ五元体系的溶解度并对所绘相图进行了分析,讨论了硼酸的分离及其对硫酸钠转化制硫酸钾的影响     

三元体系Li2SO4-Li2B4O7-H2O在323．15K时相平衡研究

采用等温溶解平衡法研究了三元体系Li2SO4-Li2B4O7-H2O在323．15K时的溶解度及其平衡溶液的密度、pH性质,根据实验数据绘制了相应的平衡相图及其物化性质组成图。研究结果表明：该三元体系在323．15K时有2个结晶相区（Li2B4O7·3H2O和Li2SO4·H2O）、2条单变量溶解度曲线、1个共饱点,属简单共饱型。     

Field measurements of aerosol particle dry deposition on tropical foliage at an urban site

This paper presents dry deposition of major ions on tropical foliage (leaves of Ashok (Polyalthia longifolia) and Cassia (Cassia siamea)) at St. John's, Agra, an urban site of tropical India on nonrainy, nondewy, and nonfoggy days. The deposition flux was higher on Cassia leaf than Ashok leaf probably due to a rougher surface as shown by scanning electron microscopy. Dry deposition of cations varies from 0.46 to 12.16 mg m(-2) day(-1) while anions vary from 0.04 to 3.24 mg m(-2) day(-1). The percentage contribution of alkaline components is greater than that of acidic components, indicating the alkaline nature of dry deposition. Two-way analysis of variance results reveal significant seasonal variation only for K+, SO4(2-), and F-; however, values varied season to season for Na+, Ca2+, Mg2+, Cl-, NO3-, and NH4+ also. The large seasonal variation in deposition flux may be due to meteorological conditions, diameter of particles, and variation in atmospheric level. SO42- and NO3- show significant correlation, indicating their origin from similar sources while significant correlation between Ca2+ and Mg2+ implies their origin from soil. Poor correlation between Ca2+ and SO4(2-), Ca2+ and NO3-, and Mg2+ and SO4(2-) indicates that in addition to soil other sources also contribute to dry deposition. Low dry deposition fluxes of SO2- and NO3- compared to Ca2+ and Mg2+ may be due to low mass medium diameters of SO4(2-) and NO3- and may be due to uptake through the stomatal pores abundant on leaf surfaces. Factor analysis was employed to identify the sources. F-, Cl, SO4(2-), NO3-, and K+ are grouped together in the first factor, indicating their probable contribution from combustion, Ca2+, Mg2+, and NH4+ are grouped in factor II, which may be attributed to road dust and soil, and factor III includes mainly Na+ and F-, probably contributed from brick-kiln industries. Atmospheric concentrations of F-, Cl-, NOs-, SO4(2-), Na+, K+, Ca2+, Mg2+, and NH4+ were found to be 0.38, 2.28, 1.31, 2.74, 0.44, 0.59, 1.21, 1.2, and 2.29 microg m(-3), respectively.     

Influence of agricultural biomass burning on aerosol size distribution and dry deposition in southeastern Brazil

The size distributed composition of ambient aerosols is used to explore seasonal differences in particle chemistry and to show that dry deposition fluxes of soluble species, including important plant nutrients, increase during periods of biomass (sugar cane trash) burning in S?o Paulo State, Brazil. Measurements were made at a single site centrally located in the State's sugar cane growing region but away from the immediate vicinity of burns, so that the airsampled was representative of the regional background. Calculation of ion equivalent balances showed that during burning periods smaller particles (Aitken and accumulation modes) were more acidic, containing higher concentrations of SO4(2-), oxalate, NO3-, HCOO-, CH3COO-, and CI-, but insufficient NH4+ and K+ to achieve neutrality. Larger particles showed an anion deficit due to the presence of unmeasured ions and comprised resuspended dusts modified by accumulation of nitrate, chloride, and organic anions. Increases of resuspended particles during the burning season were attributed to release of earlier deposits from the surfaces of burning vegetation as well as increased vehicle movement on unsurfaced roads. During winter months the relative contribution of combined emissions from road transport and industry diminished due to increased emissions from biomass combustion and other activities specifically associated with the harvest period. Positive increments in annual particulate dry deposition fluxes due to higher fluxes during the sugar cane harvest were 44.3% (NH4+), 42.1% (K+), 31.8% (Mg2+), 30.4% (HCOO-), 12.8% (CI-), 6.6% (CH3COO-), 5.2% (Ca2+), 3.8% (SO4(2-)), and 2.3% (NO3-). Na+ and oxalate fluxes were seasonally invariant. Annual aerosol dry deposition fluxes (kg ha(-1)) were 0.5 (Na+), 0.25 (NH4+), 0.39 (K+), 0.51 (Mg2+), 3.19 (Ca2+), 1.34 (Cl-), 4.47 (NO3-), 3.59 (SO4(2-)), 0.58 (oxalate), 0.71 (HCOO-), and 1.38 (CH3COO-). Contributions of this mechanism to combined aerosol dry deposition and precipitation scavenging (inorganic species, excluding gaseous dry deposition) were 31% (Na+), 8% (NH4+), 26% (K+), 63% (Mg2+), 66% (Ca2+), 32% (Cl-), 33% (NO3-), and 36% (SO4(2-)).     

Crystallization Kinetics and X-ray Diffraction of Crystals Formed in Amorphous Lactose, Trehalose, and Lactose/Trehalose Mixtures

ABSTRACT: Effects of storage time and relative humidity on crystallization kinetics and crystal forms produced from freeze-dried amorphous lactose, trehalose, and a lactose/trehalose mixture were compared. Samples were exposed to 4 different relative water vapor pressure (RVP) (44.1%, 54.5%, 65.6%, 76.1%) environments at room temperature. Crystallization was observed from time-dependent loss of sorbed water and increasing intensities of peaks in X-ray diffraction patterns. The rate of crystallization increased with increasing storage humidity. Lactose crystallized as α-lactose monohydrate, β-anhydrous, and anhydrous forms of α- and β-lactose in molar ratios of 5:3 and 4:1 in lactose and lactose/trehalose systems. Trehalose seemed to crystallize as a mixture of trehalose dihydrate and anhydrate in trehalose and lactose/trehalose systems. The crystal forms in a mixture of lactose and trehalose did not seem to be affected by the component sugars, but crystallization of the component sugars was delayed. Time-dependent crystallization of lactose and trehalose in the lactose-trehalose mixture could be modeled using the Avrami equation. The results indicated that crystallization data are important in modeling of crystallization phenomena and predicting stability of lactose and trehalose-containing food and pharmaceutical materials. Keywords: crystallization, lactose, trehalose, crystal form, X-ray diffraction     

The influence of acidic diets on the acid-base balance of dry cows and the effect of fertilization on the mineral content of grass.

To investigate the safety and practicality of an acidic concentrate in milk fever prevention, the pH, carbon dioxide, standard bicarbonate, and base excess of whole blood and the pH in the urine were measured in three treatment groups of dry cows after 14 and 21 d of feeding an acidogenic diet (experiment 1). The dietary cation-anion differences (DCAD) of cows on treatments 1 (n = 11), 2 (n = 13), and 3 (n = 12) were +2275, -262, and -1185 meq/d, respectively. No changes in any parameters were found from the beginning to the end of the experiment in cows on treatment 1. In cows on treatment 2, a significant reduction in urine pH was observed, and in cows on treatment 3 significant decreases in all parameters except blood pH were observed. Mineral analyses of grass samples from fields fertilized with N from NH4NO3, Ca(NO3)2, or (NH4)2SO4, with S from (NH4)2SO4, and with different amounts of K from KCl or K2SO4 and of Cl from KCl revealed DCAD ranging from -14 to +726 meq/kg of dry matter (experiment 2). Fertilization with Cl increased the chloride concentration in the crop and had the largest effect on DCAD. The results indicate that the use of acidic concentrates is not a health hazard for dry cows, at least not when the DCAD is greater than about -1200 meq/d or about -140 meq/kg of dry matter.     

Li2CO3-Li2SO4-Li2B4O7-H2O四元体系273.15K介稳相平衡研究

采用等温蒸发法研究了四元体系Li2CO3-Li2SO4-Li2B4O7-H2O273.15K介稳相平衡,测定了该四元体系273.15K条件下介稳相平衡溶液的溶解度和密度,根据实验数据绘制了相应的相图.研究发现:该体系为简单共饱和型,无复盐及固溶体形成;相图中包含一个共饱点E,三条单变度曲线EE1,EE2,EE3,三个单盐结晶区,单盐形式分别为Li2CO3,Li2SO4·H2O,LBO2·8H2O.