共查询到18条相似文献，搜索用时 527 毫秒
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用等压法研究了LiCl-Li2 B4O7-H2 O体系离子强度范围为 0 1 5 3 0～ 3 0 75 8mol kg-1不同质量摩尔浓度分数的等压平衡浓度 ,水活度 ;计算了LiCl和Li2 B4O7,混合盐溶液的饱和蒸汽压 ,渗透系数等热力学性质。以总硼浓度 0 0 8mol·kg-1为界 ,把所有混合盐的实验数据分为高浓度和低浓度两部分 ,按照不同的物种生成转化反应 ,考虑溶液中H3 BO3 和硼氧配阴离子B(OH) 4 -,B3 O3 (OH) 4 -和B4O5(OH) 4 2 -的存在形式。由实验数据用最小二乘法和迭代法求取了LiB(OH) 4 离子对的缔合平衡常数Km1,B3 O3 ,(OH) 4 离子的生成转化反应的化学计量平衡常数Km2 ,以及Pitzer模型的离子相互作用参数。用该模型计算的渗透系数值与实验结果取得合理的一致。对完善含锂、硼盐湖卤水体系的热力学模型和盐湖资源的综合开发具有重要意义 相似文献
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用合成的水合四硼酸钾和偏硼酸钾晶体,配制一系列溶液,研究了pH与浓度变化的关系,并计算硼酸根离子的摩尔分数-浓度(δ-c)关系图。用拉曼光谱方法研究四硼酸钾和偏硼酸钾溶液,给出其拉曼光谱图,并对各峰进行了归属。研究表明,四硼酸钾溶液中存在的物种主要有[B4O5(OH)4]2-、[B3O3(OH)4]-和[B(OH)4]-,而其它物种所占摩尔分数很小;在偏硼酸钾水溶液中,[B(OH)4]-占绝大多数,有很少量H3BO3、[B4O5(OH)4]2-和[B3O3(OH)4]3-。硼酸盐离子浓度越低,越容易水解为聚合度较低的简单物种。 相似文献
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在Pitzer电解质溶液理论的基础上采用两种模型计算了KCl-K2SO4-KBO2-H2O体系及其子体系的溶解度。模型I假设溶液中只有一种硼物种B(OH)4-,模型II假设溶液中有4种硼物种,分别对应于B(OH)3、B(OH)4-、B3O3(OH)4-和B4O5(OH)42-。模型I与模型II的溶解度计算结果接近,且与实验值吻合较好。采用模型II计算了上述体系溶液中的硼物种和OH-的浓度。各硼物种的浓度主要受溶液中总硼浓度的影响,而很少受KCl和K2SO4的影响。计算结果说明在计算偏硼酸钾溶液体系溶解度时,可近似认为溶液中硼物种只有B(OH)4-。模型II可用于计算含偏硼酸钾体系的pH值。本文的计算结果可为复杂偏硼酸钾体系模型的构建提供理论基础。 相似文献
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采用物种分布图和核磁共振实验研究了五硼酸钾溶液中含硼物种的类型、含量和溶液浓度间关系。研究表明五硼酸钾在稀溶液中几乎全部水解为B(OH)3和B(OH)4-;在较浓溶液中主要物种为B3O3(OH)4-和B(OH)3,而B5O6(OH)4-和[B4O5(OH)42-]的含量较小。核磁共振实验研究给出了B(OH)4-, B3O3(OH)4-和B5O6(OH)4-的生成常数K1, K3, K5,研究得出B5O6(OH)4-含量很少的原因是其解聚为其它类型硼酸根离子。外加离子促进五硼酸根离子的生成,而高温条件促进B5O6(OH)4-发生解聚反应。 相似文献
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不同溶液体系中硼的赋存形态及其化学分布规律一直以来是研究者关注的重点,它对深入开展硼酸盐溶液结构化学、过饱和非平衡态以及硼酸盐矿物沉积机制等研究具有重要的指导意义。针对目前拉曼光谱仪对溶液中硼氧配阴离子官能团响应信号弱、灵敏度低,不利于定量化视角阐述硼氧配阴离子间的作用机理等问题,研究了拉曼积分球光谱仪对硼酸溶液的定量分析方法,运用 DOE部分因子实验设计,阐述了 NaCl、MgCl2、KCl和 MgSO4等共存盐类之间的交互作用对 B(OH)3拉曼定量分析的影响规律,建立了盐水溶液中 B(OH)3的 Raman回归模型。结果表明,拉曼积分球光谱仪可显著增大硼酸溶液的拉曼光谱强度,提高信噪比,检出限为常规拉曼光谱的 70倍,在 0～6g·L-1硼酸线性范围内相关系数为 0.9991,测定相对误差为 -2.5%;盐水溶液中 B(OH)3含量经回归方程校正后相对误差绝对值小于 3%,可用于低浓度硼酸的准确定量分析,也为定量化探究盐卤复杂体系中多硼物种化学形态分布规律提供一定借鉴。 相似文献
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利用牛顿迭代方法计算给出硼酸钾溶液中硼酸根离子的物种分布图。研究给出溶液中硼酸根离子的类型、含量以及各硼酸根离子间相互转化方程式,并简单谈论了温度和浓度对硼酸根离子类型和含量的影响。在五硼酸钾溶液中主要硼酸根离子物种为B3O3(OH)4-,B4O5(OH)42-和B(OH)3,而B5O6(OH)4-含量非常低,可以忽略不计;偏硼酸钾溶液中主要离子为B(OH)4-;在高浓四硼酸钾溶液中主要物种为B3O3(OH)4-,B4O5(OH)42-和B(OH)4-。最后用Otakar和Casteel-Amis经验方程式分别研究了硼酸钾溶液的密度和电导率。 相似文献
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与多羟基化合物络合是去除和分离溶液中微量硼的有效手段,但我们对多羟基化合物与硼酸盐的反应缺乏深入认识。本文通过测定硼酸/硼砂与木糖醇、D-果糖、D-山梨醇和D-甘露醇在水溶液中反应的pH、电导率及Raman光谱,综合对比研究了硼酸/硼砂与四种多羟基化合物的络合反应。对于多羟基化合物/硼酸水溶液,随着多羟基化合物浓度的增加,溶液的pH值降低,电导率显著增加。对于多羟基化合物/硼砂水溶液,随着多羟基化合物浓度的增加,溶液的pH值和电导率都是首先明显降低,之后缓慢降低。为使硼酸/硼砂络合完全,多羟基化合物与硼酸的物质量的比要大于2。四种多羟基化合物与硼酸反应后,都出现了新的Raman峰,D-甘露醇与硼酸在溶液中反应后,在1 207 cm~(-1)处出现了较强的Raman峰。在四种多羟基化合物中,D-甘露醇与硼酸/硼砂的反应效果更好。 相似文献
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The crystal structure of metal borates has been extensively investigated by X-ray and neutron diffraction,but,the structure of aqueous polyborate solutions are still largely unknown.Over the last decade,our group has focused on studying the structure of complex aqueous polyborate solutions of Li,Na,K,Rb,Cs,and Mg using synchrotron radiation X-ray scattering(XRS),EXAFS,Raman,NMR,and DFT,as well as determining the density,conductivity and pH of such solutions.Polyborate species distributions were calculated using pH measurements,and the main species in the solution have been confirmed by NMR and Raman spectra.For alkali-metal metaborates,the dominant species is always B(OH)-4in a wide range of concentration,while the presence of others species is negligible.For alkali metal tetraborates,when concentration is in the extreme low range,only B(OH)3 and B(OH)-4 are present in these solutions.As the total boron concentration increases,B(OH)3 and B(OH)-4 polycondensated to form more complex oligomers.Of them,while B4O5(OH)2-4 in the tetraborate solutions is the main species,B(OH)3,B(OH)-4,and B3O3(OH)-4 are minor species,and B3O3(OH)2-5 and B5O6OH)-4 are present only in negligible amounts.As solution continues to concentrate,B4O5(OH)2-4 eventually becomes the dominant species,which is consistent with the congruent compound M2B4O7·nH2O(M=Li,Na,K,Rb,Cs) in the system M2O-B2O3-H2O(M=Li,Na,K,Rb,Cs).For alkali metal pentaborates,B(OH)3 and B(OH)-4 are the main species at low concentrations.The species distribution,Raman and NMR spectroscopy results verified that the dominant species in concentrated pentaborate solutions with Li and Na is pentaborate B5O6OH)-4,but it is surprising that the main species with K,Rb,and Cs is always the triborate monoanion B3O3(OH)-4.Although all M[B5O6OH)4]·nH2O(M=Li,Na,K,Rb,Cs) are all congruent compounds in the system M2O-B2O3-H2O(M=Li,Na,K,Rb,Cs) ,the main species in aqueous solutions are quite different because of various cation hydration distance(d),hydration number(CN),and configuration,especially charge(Z).For bivalent Mg2+,three borate minerals,namely,Inderite(2MgO·3B2O3·15H2O),Hungchaoite(MgO·2B2O3·9H2O),and Mcallisterite(MgO·3B2O3·7.5H2O),exist in the system MgO-B2O3-H2O at 298K.Inderite is a congruent compound,but Hungchaoite and Mcallisterite are incongruent compounds.The species distribution and Raman spectra demonstrat that the predominant species in all the solutions with magnesium borates is bivalent triborate B3O3(OH)2-5,while the subordinate species are B(OH)-4 at a low B2O3/MgO ratio and B(OH)3at a high B2O3/MgO ratio,and the other anions are negligible,as the high Z of the borate anion must match that of Mg2+.The disappearance of divalent B4O5(OH)2-4 is in agreement with its incongruent nature.The DFT and XRS results showed that tetrahedral Li(H2O)+4(d=0.20 nm,CN=4),octahedral Na(H2O)6+(d=0.236 nm,CN=6),and Mg(H2O)2+6(d=0.210 nm,CN=6) in the first hydration shell belong to Platonic polyhedra.However,K(H2O)+8(d=0.28 nm,CN=8,XRS and DFT),Rb(H2O)+8(d=0.293 nm,CN=7.7-8.2,EXAFS),and Cs(H2O)+8(d=0.320-0.326 nm,CN=7.6-7.9,EXAFS) are inclined Voronoi polyhedra.Therefore,the effects of cation Z and d on the structure of polyborates in aqueous solutions are deterministic,while the effect of hydrated-cation symmetry is secondary.Their hydrolysis order was:Mg＞Li＞Na＞K＞Rb＞Cs,in step with hydration power.Among them,Mg2+ and Li+have a strong tendency towards hydrolysis,but Na+ scarcely hydrolyzes,especially Rb+ and Cs+ have a little protonation.X-ray scattering of aqueous alkaline sodium borohydride solutions confirmed that dihydrogen bonds exist in an aqueous solution.The four distinct features of dihydrogen bonds in aqueous solution-unidirectionality,divaricativity,multicentricity,and multidentativity have been also described here in brief. 相似文献
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Boron resources are abundant in Da Qaidam salt lake of Qaidamu Basin. It has been given great attention for the polyborate species present in brine. In this study, the Raman spectroscopy was applied to investigate the existing-form of boron in brine during evaporation. The prepared solutions of MgO·2B2O3-H2O, MgO·2B2O3-MgCl2 -H2O, and MgO·2B2O3-MgSO4-H2O was also evaporated and recorded to study the influence of boron concentration, pH, and electrolytes on the borate speciation in brine. The mononborates of B(OH)3 and B(OH)4- were found to be the only forms present in the original salt lake brine. Brine evaporation promotes the formation of polyborate anions B3O3(OH)4-, B5O6(OH)4-, and B6O7(OH)62- and also disappearance of the B(OH)4- ion in brine with boron concentration of more than 11 g/L in B2O3. The pentaborate ion of B5O6(OH)4- was sensitive to the solution pH and found to be appeared under the pH value of 8.0. While the hexaborate ion of B6O7(OH)62- was observed more dependent on the electrolyte of magnesium chloride due to its special properties, such as promoting boron accumulation, lowering solution pH, and also the strong af?nity for water molecules, which is beneficial to the polymerization of borate ions in brine. The interaction mechanisms among polyborate anions during evaporation had also been proposed. 相似文献
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硫酸镁亚型盐湖老卤是MgCl2、MgSO4的饱和溶液体系,富集了Mg、B、Li等元素。本文针对含硼水盐体系热力学难以表达的问题,开展了硼在水盐体系存在形态及其平衡关系的研究。利用易于水解的Mg(BO2)2作为硼源,借助拉曼光谱和X射线衍射(XRD)为检测手段,定量研究Mg(BO2)2在MgSO4-H2O、MgSO4-MgCl2-H2O体系中水解硼物种转化规律。结果表明:(1)Mg(BO2)2在MgSO4溶液中的水解固相为MgB2O(OH)6、MgB4O7·9H2O和Mg(OH)2;在MgSO4-MgCl2-H2O溶液中水解固相为Mg2B6O11·15H2O、MgB4O7·9H2O、Mg2Cl(OH)3·4H2O。(2)Mg(BO2)2在MgSO4溶液中水解,液相硼物种主要有B3O3(OH)-4、B3O3(OH)52-、B(OH)-4、B4O5(OH)42-、H3BO3,其分布受MgSO4浓度影响很大,MgSO4浓度从0增加至饱和,B3O3(OH)-4始终占总硼量的50.07%以上,B3O3(OH)52-占液相总硼从4.77%上升至37.16%为第2化学物种。(3)在MgSO4-MgCl2-H2O溶液中,硼物种的主要形态有B3O3(OH)-4、B3O3(OH)52-、B(OH)-4,其分布 随[Cl22-]/([Cl22-]+[SO42-])变化很大,在MgCl2和MgSO4的共饱溶液中,分别占液相总硼量的58.91%,14.62%和12.81%。(4)液相硼物种之间平衡关系的活度商lnQ,不仅与溶液pH、水活度有关,还与MgSO4、MgCl2摩尔浓度呈二元线性关系,这样就可将硼在H3BO3-NaOH体系物种分布关系的lnQ扩展到 (MgSO4,MgCl2,MgSO4-MgCl2)水溶液的多元体系。由此获得硼物种的量化关系,可为推算硼在水盐体系的物种分布,进而计算含硼电解质溶液热力学性质提供依据。 相似文献
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本文对AmberliteIRA743硼特效树脂交换分离础的特性及其影响因素进行了研究.它适用于各种地质作品中硼的分离提取，特别是在硼同位素地球化学研究时。必须进行础纯化的场合。 相似文献
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研究了用2-乙基己醇作萃取剂从高浓度氯化镁卤水中萃取硼的工艺。先用分液漏斗通过单因素和正交实验优化了萃取与反萃取的工艺条件,作出了萃取与反萃等温线。结果表明,萃取最佳条件:pH=1.8,盐(MgCl_2)浓度28%以上;反萃pH大于2.3。由McCabe-Thiele图解法得到逆流萃取和反萃取级数分别为3和4级。然后用8台Ф20 mm离心萃取器进行了连续逆流萃取与反萃取硼的实验。结果表明,离心萃取器在较大的流比和转速范围内级效率达到99%以上;用4台离心萃取器进行连续逆流萃取,硼的总萃取率达到96.9%;负载有机相用4台离心萃取器进行连续逆流反萃取,硼的总反萃取率达到99.8%。 相似文献