碱式氯化镁5Mg(OH)2·MgCl2·3H2O的制备与表征

以氨水和盐湖盛产的水氯镁石为原料经过两步反应制备碱式氯化镁。第一步,水氯镁石和氨水反应制备氢氧化镁;第二步,利用氢氧化镁和水氯镁石,通过水热反应得到了具有纤维形貌、结晶较好的碱式氯化镁。应用化学分析、XRD、SEM和FIIR等手段对产物进行测试与表征。化学分析结果表明产物组成为5Mg(OH)₂·MgCl₂·3H₂O。将得到的5Mg(OH)₂·MgCl₂·3H₂O和碱式氯化镁系列标准XRD图对照,未有较好的匹配,且结合化学分析和已报道碱式硫酸镁具有5Mg(OH)₂·MgSO₄·3H₂O物相,因而推测其为新物相;SEM图中5Mg(OH)₂·MgCl₂·3H₂O纤维直径约为0.4 μm,平均长度大于24 μm,长径比大于60;FTIR图谱中3 419 cm^-1附近出现了氢键的O-H伸缩振动吸收峰,1 635 cm^-1附近出现了游离水中H-O-H的弯曲振动吸收峰。水热合成的5Mg(OH)₂·MgCl₂·3H₂O和常压下的产物相比直径较小,晶形更完整,强度更高。     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Mg(OH)2· 2MgSO4· 2H2O晶体的水热生长过程

对 MgSO4- NaOH- H2O四元交互体系在 160 ℃水热条件下 ,相同物料配比 ,不同反应时间的晶体生长过程进行了研究 ,得到 5Mg(OH)2@ MgSO4@ 2H2O(简称 MOS)晶须和 Mg(OH)2@ 2MgSO4@ 2H2O棒状晶体两种硫氧镁化合物 .通过化学分析、 X- ray粉末衍射、 FT- IR光谱和 SEM对反应产物进行了表征 .前者是该体系水热条件下介稳产物 ,而新的硫氧镁化合物 Mg(OH)2@ 2MgSO4@ 2H2O是该体系的稳定相.     

Mg(OH)2•2MgSO4•2H2O晶体的水热生长过程

对MgSO4-NaOH-H2O四元交互体系在160 ℃水热条件下,相同物料配比,不同反应时间的晶体生长过程进行了研究,得到5Mg(OH)2•MgSO4•2H2O(简称MOS)晶须和Mg(OH)2•2MgSO4•2H2O棒状晶体两种硫氧镁化合物.通过化学分析、X-ray粉末衍射、FT-IR光谱和SEM对反应产物进行了表征.前者是该体系水热条件下介稳产物,而新的硫氧镁化合物Mg(OH)2•2MgSO4•2H2O是该体系的稳定相.     

X射线内标法测定氯氧镁水泥中的相含量

1引言 氯氧镁水泥(以下简称镁水泥),又称索瑞尔水泥(Sorel)[1],是由活性MgO、MgCl2和水形成的气硬性材料.镁水泥初期的相主要是相5(5Mg(OH)2·MgCl2·8H2O)和相3(3Mg(OH)2·MgCl2·8H2O).这两种相均不很稳定,受大气中CO2的作用而碳化为新相2(2MgCO3·Mg(OH)2·MgCl2·6H2O)[2].中期的镁水泥样品中会出现相2.在室外的镁水泥样品会受到CO2和水的双重作用.CO2的碳化和水的溶解浸蚀协同作用会使相2继续发生转化,最终会生成稳定相4(4MgCO3·Mg(OH)2·4H2O),即水菱镁矿[3],也可能有MgCO3生成(相1).所以后期的镁水泥室外样品是含有相4和相1这两种稳定相的.     

过渡金属离子掺杂Zn3(OH)2V2O7·2H2O的合成及其光催化性质

利用水热法合成了3d过渡金属离子掺杂Zn3(OH)2V2O7·2H2O的微米花结构,其分子式可表达为Zn3-3xM3x(OH)2V2O7·2H2O(其中M=Cu,Co,Ni,Mn;0.001≤x≤0.20)。应用XRD、SEM、TEM、UV-Vis DRS、EDX和BET等分析测试技术对产物进行了表征。结构和形貌分析结果显示过渡金属离子掺杂后产物仍保持Zn3(OH)2V2O7·2H2O的六方晶体结构,微米花由主晶面为(0001)的纳米片组装而成。紫外-可见漫反射光谱显示过渡金属离子掺杂后带边吸收红移,其中以Cu的掺杂产物Zn3-3xCu3x(OH)2V2O7·2H2O最为明显,带边吸收扩展到可见光区。首次对Zn3(OH)2V2O7·2H2O及其不同金属离子掺杂产物Zn3-3xM3x(OH)2V2O7·2H2O进行了可见光催化降解有机污染物的研究,结果显示与其它产物相比掺0.1at%Cu的Zn2.997Cu0.003(OH)2V2O7·2H2O对亚甲基蓝(MB)的可见光催化降解效果最好。对掺杂离子种类、掺杂离子浓度对产物可见光催化性质的影响也进行了考察。     

Al(Ⅲ)盐水解聚合过程中Al5和Al9的制备及初步表征

采用铝粉、水合氯化铝和水为原料,通过调整反应温度、原料配比及溶液碱化度,经蒸发、结晶制备了铝盐水解聚合产物中的2种中间产物,即水合氯化五聚铝AlCl3·4Al(OH)3·7.5H2O和水合氯化九聚铝2AlCl3·7Al(OH)3·18H2O分别采用粉末XRD物相分析、化学分析和IR光谱对其进行了表征. 以化学分析为主要监测手段,对AlCl3·4Al(OH)3·7.5H2O和2AlCl3·7Al(OH)3·18H2O的形成过程进行了研究. 结果表明,随温度的变化反应基本上是一个可逆的过程,75 ℃是AlCl3·4Al(OH)3·7.5H2O和2AlCl3·7Al(OH)3·18H2O析出的最佳温度,该温度下产物的结晶状态良好,其纯度分别可达99.57%和88.68%.     

Na~+,K~+,Mg~(2+)∥Cl~-,SO_4~(2-)-H_2O五元体系35℃介稳相图研究

研究得出 (Na+ ,K+ ,Mg2 +∥ Cl-,SO2 -4 -H2 O)五元体系 3 5℃时的介稳溶解度数据 ,绘制了该体系 3 5℃的介稳相图 ,共有 9个为氯化钠所饱和的结晶区域 :氯化钾、钾芒硝 (3 K2 SO4 · Na2 SO4 )、钾镁矾 (K2 SO4· Mg SO4 · 4 H2 O)、钾盐镁矾 (KCl· Mg SO4 · 2 .75H2 O)、光卤石 (KCl· Mg Cl2 · 6H2 O)、白钠镁矾 (Na2 SO4· Mg SO4 · 4 H2 O)、硫酸钠、六水硫酸镁 (Mg SO4 · 6H2 O)和水氯镁石 (Mg Cl2 · 6H2 O) .所得 3 5℃介稳相图与 Van t Hoff2 5℃稳定相图比较有较大区别 :软钾镁矾 (K2 SO4 · Mg SO4 · 6H2 O)、七水硫酸镁、五水硫酸镁及四水硫酸镁结晶区域消失 ,钾镁矾和钾盐镁矾结晶区域显著扩大 .所得 3 5℃介稳相图与 2 5℃介稳相图区别很大 :软钾镁矾和七水硫酸镁结晶区域消失 ,同时出现了钾镁矾和钾盐镁矾的结晶区域 .在该五元体系 3 5℃介稳相平衡研究中发现析出的是钾盐镁矾的低水化合物 (KCl·Mg SO4 · 2 .75H2 O)     

2MgO·2B2O3·MgCl2·14H2O-H2O体系在沸点温度的相转化研究

2MgO·2B2O3·MgCl2·14H2O(氯柱硼镁石)是从天然浓缩盐卤中得到的一种新硼酸镁盐[1].已报道过在实验室中模拟合成盐卤对该复盐的合成条件[2].为了探讨该复盐在盐湖沉积过程中的形成和转化条件,对其在10～60℃水中溶解及相转化动力学过程做过研究,其中10～50℃时的最终溶解转化产物是2MgO·3B2O3·15H2O(多水硼镁石)[3],60℃是MgO.B2O3.H2O(柱硼镁石)[4].     

298.16K下K+,Mg2+//Cl-,NO-3-H2O体系液固相平衡

采用等温溶解平衡法研究298.16K时四元体系K+,Mg2+//Cl-,NO-3-H2O的液固相平衡关系,测定了溶解度数据,并绘制出平衡相图.研究表明,在298.16K时,该体系相图有5个单盐结晶区、6条单变量溶解度曲线和3个零变量点.5个单盐结晶区分别对应于KNO3、KCl、Mg(NO3)2·6H2O、MgCl2O和复盐KCI·MgCl2·6H2O,其中KNO3的结晶区最大,MgCl2·6H2O的结晶区最小.     

Chemistry of borate in salt lake brine (XXXIV) ——Phase diagram of thermodynamic nonequilibrium state of MgO-B_2O_3-18%MgCl_2-H_2O system at 20℃

The crystallization processes of hydrated Mg-borates, boric, magnesium hydroxide and Mg-oxychloride from MgO-B2O3-18%MgCl2-H2O supersaturated solution at 20℃ have been studied by kinetic method. The crystallization solid phases were characterized by X-ray powder diffraction, IR spectra, thermal analysis and chemical analysis. The liquid-solid phase diagram of ther-modynamic nonequilibrium state has been given. In this phase diagram, there exist eight crystallization fields, boric acid(H3BO3), trigomagneborite(MgO · 3B2O3 · 7.5H2O, MgO · 3B2O3 · 7H2O), hungchaoite(MgO ·2B2O3 ·9H2O), inderite(2MgO ·3B2O3 · 15H2O), chloropinnoite(2MgO ·2B2O3 · MgCl2 · 14H2O), magnesium hydroxide(Mg(OH)2) and magnesium oxychloride (5Mg(OH)2 · MgCl2·8H2O).     

A new approach to studying aqueous reactions using diffuse reflectance infrared Fourier transform spectrometry: application to the uptake and oxidation of SO2 on OH-processed model sea salt aerosol

Diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) is a powerful technique for analyzing solid powders and for following their reactions in real time. We demonstrate that it can also be applied to studying the uptake and reactions of gases in liquid films. Within the DRIFTS cell, a 10%(w/w) mixture of MgCl(2) x 6H(2)O in NaCl was equilibrated with air at 50% RH, which is above the deliquescence point of the magnesium salt but below that of NaCl. This mixture of NaCl coated with an aqueous magnesium chloride solution was then reacted with gas phase OH to generate hydroxide ions via a previously identified interface reaction. This treatment, hereafter referred to as OH-processing, was sufficient to convert some of the magnesium chloride to Mg(OH)(2) and Mg(2)(OH)(3)Cl x 4H(2)O, making the aqueous film basic and providing a reservoir of alkalinity. Subsequent addition of SO(2) to the basic processed mixture resulted in its uptake and conversion to sulfite which was measured by FTIR. The sulfite was simultaneously oxidized to sulfate by HOCl/OCl(-) that was formed in the initial OH-processing of the salt. Further uptake and oxidation of SO(2) in the aqueous film took place when the salt was subsequently exposed to O(3). These studies demonstrate that DRIFTS can be used to study the chemistry in liquid films in real time, and are consistent with the hypothesis that the reaction of gaseous OH with chloride ions generates alkalinity that enhances the uptake and oxidation of SO(2) under these laboratory conditions.     

Synthesis of Mg5(CO3)4(OH)2·4H2O with Flower-like Microstructure and Its Catalytic Activity for Transesterification of Dimethyl Carbonate with Phenol

A novel flower-like hydrated magnesium carbonate hydroxide, Mg5(CO3)4(OH)2 · 4H2O, with micro-structure composed of individual thin nano-sheets was synthesized using a facile solution route without the use of template or organic surfactant. Reaction time has an important effect on the final morphology of the product. The micro-structure and morphology of Mg5(CO3)4(OH)2·4H2O were characterized by means of X-ray diffractometry ( XRD), fieldemission scanning electron microscopy(FE-SEM). Brunauer-Emmett-Teller(BET) surface areas of the samples were also measured. The probable formation mechanism of flower-like micro-structure was discussed. It was found that Mg5(CO3)4(OH)2·4H2O with flower-like micro-strucure was a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate (DMC) with phenol.     

玫瑰花状多孔碱式碳酸镁微球的合成

介绍了一种便利的玫瑰花状多孔碱式碳酸镁(4MgCO₃·Mg(OH)₂·4H₂O)微球的合成方法,该方法分为三水碳酸镁(MgCO₃·3H₂O)前驱物合成与其在水中的热解制备过程。采用搅拌诱导结晶辅助陈化的方法合成前驱物,得到长约115 μm,长径比约10.4的均一微棒,将微棒在353.2 K的水中热解,即可得到由弯曲的纳米片组成的具有“卡片箱”结构（house of cards）的玫瑰花状多孔碱式碳酸镁微球,微球直径为30~60 μm,平均约40 μm,具有良好分散性。研究了热解过程中的形貌转变和相转移过程,采用XRD,FTIR及SEM表征样品的结构和形貌。结果表明：MgCO₃·3H₂O在较高温度下因不稳定而溶解,形成局部过饱和,生成无定形颗粒,并在微棒上成核结晶为4MgCO₃·Mg(OH)₂·4H₂O纳米片。纳米片由与微棒附着部位向外生长,形成玫瑰花状微球,微球长大伴随微棒的消溶,生长在棒上不同部位的颗粒在微观结构上将留有不同痕迹。分析认为热解转变过程是(MgCO₃·3H₂O)溶解－无定形物生成-(4MgCO₃·Mg(OH)₂·4H₂O)结晶的过程。     

棒状氢氧化镁的合成

以氯化镁和氢氧化钠为原料合成了棒状氢氧化镁粉体。考察了氢氧化钠浓度、陈化温度、陈化时间对氢氧化镁形貌的影响。采用SEM、HRTEM、XRD、TG等对所得氢氧化镁颗粒的形貌、颗粒大小、晶习及热稳定性进行了表征。结果表明,当陈化温度为90℃时,所得棒状氢氧化镁随氢氧化钠浓度的升高及陈化时间的增加,晶形更加完整;当陈化温度在120℃时,所得氢氧化镁颗粒的形貌为片状,不能得到棒状氢氧化镁。     

酸蒸气水热法合成钒取代水合碱式钨钼酸锆纳米晶体及热收缩Zr(WMo)0.93V0.14O7.93化合物

研究了酸蒸气水热法(ASH)合成VWMo.H2O时,酸蒸气源溶液的浓度,反应温度,填满度与反应时间等4个因素对晶体成核和生长两个阶段的影响。确定了以上4个影响因素的优化匹配条件,制备了VWMo.H2O纳米晶棒,并且对产物进行了表征。HCl-ASH法和HNO3-ASH法合成的VWMo.H2O化学式分别为Zr(WMo)0.93V0.14O6.93(OH0.92Cl0.08)2.(H2O)2和Zr(WMo)0.93V0.14O6.93(OH)2.(H2O)1.64;两者都与ZrMo2O7(OH)2.(H2O)2为同构化合物。以VWMo.H2O为前驱物在773K合成了立方热收缩化合物β-Zr(WMo)0.93V0.14O7.93。     

The synthesis and spectroscopic characterisation of hydrotalcite formed from aluminate solutions

Raman spectroscopy has been used to characterise nine hydrotalcites prepared from aluminate and magnesium solutions (magnesium chloride and seawater). The aluminate hydrotalcites are proposed to have the following formula Mg(6)Al(2)(OH)(16)(CO(3)(2-))·xH(2)O, Mg(6)Al(2)(OH)(16)(CO(3)(2-),SO(4)(2-))·xH(2)O, and Mg(6)Al(2)(OH)(16)(SO(4)(2-))·xH(2)O. The synthesis of these hydrotalcites using seawater results in the intercalation of sulfate anions into the hydrotalcite interlayer. The spectra have been used to assess the molecular assembly of the cations and anions in the hydrotalcite structures. The spectra have been conveniently subdivided into spectral features based upon the carbonate anion, the hydroxyl units and water units. This investigation has shown the ideal conditions to form hydrotalcite from aluminate solutions is at pH 14 using a magnesium chloride solution at a volumetric ratio of 1:1. Changes in synthesis conditions resulted in the formation of impurity products aragonite, thenardite, and gypsum.     

MgSO_4·5Mg(OH)_2·3H_2O的水热合成及反应时间对其形貌的影响(英文)

０IntroductionWhiskerswithhighaspectratiohavebeenexten－sivelyusedascompositematerialsinalloys，ceramics，cementandplastic犤１～５犦，sincetheyhavespecificdesirepropertiessuchashighmeltingpoint，lowdensityandhighmodulus犤６犦．Magnesiumoxysulfate（MOS）com－poundshowsthehighcrystallinityandaspectratiotomakeitapotentialreinforcingmaterialforplastics，resinandrubber犤７，８犦．Inpastyears，MgSO４·５Mg（OH）２·３H２Ohasbeensynthesizedbyhydrothermalreactionusingmagnesiumhydroxideandmagnesium…     

MgSO4·5Mg(OH)2·3H2O的水热合成及反应时间对其形貌的影响

Both whisker and nanometer MgSO₄·5Mg(OH)₂·3H₂O(MOS) were prepared by hydrothermal method at 140℃ for different times， using NaOH and MgSO₄·7H₂O as raw materials. The MgSO₄·5Mg(OH)₂·3H₂O part- icles were characterized by powder X-ray diffraction(XRD)，thermal analysis(TGA-DSC)， infrared spectroscopy(FT-IR)，transmission electron microscopy(SEM) and scanning electron microscopy(TEM). The size distribution in whisker-like and nanocrystalline materials are in the range of 10～50μm and 10～20nm respectively. The whisker MOS is metastable phase in MgSO₄-NaOH-H₂O system at 140℃，whereas nanometer MOS is stable phase.