氧化铝熟料溶出过程中SiO2的行为

对烧结法生产氧化铝熟料溶出过程中的主要相关二次反应进行了热力学分析,研究了溶出过程中SiO2的行为. 结果表明,b-2CaO×SiO2在铝酸钠3种溶液成分中的热力学稳定性次序为NaOH>>NaAl(OH)4>Na2CO3,即NaOH非常难以分解2CaO×SiO2,后两者则明显容易得多;提高溶出温度,只有Na2CO3与2CaO×SiO2的作用有助于溶液中SiO2浓度的增加;NaAl(OH)4和Na2CO3对二次反应的发生起重要作用,而NaOH作用较小;增加游离Na2Ok浓度,溶出液中SiO2浓度逐渐降低;铝酸钠溶液体系中的碳酸钠与水化石榴石的作用较弱.     

腐植酸(钠)在溶出、沉降分离工艺中适宜的添加量及在不同溶出温度下对经济指标的影响

本文对腐植酸(钠)在氧化铝生产溶出工艺中适宜的添加量及腐植酸(钠)在不同溶出温度下对经济指标Al_2O_3、Na_2O溶出率的影响进行了探讨。认为适宜的腐植酸(钠)添加量应是溶出熟料量的0.1～0.2％;在现生产溶出温度变化范围内腐植酸(钠)均有较高的适应性,并皆能提高NaAlO_2溶液的稳定性,尤以在较高溶出温度下对提高经济指标Al_2O_3、Na_2O的溶出率有较大影响。     

长石在压蒸条件下的碱溶出

测试了压蒸条件下两种天然长石在水及饱和Ca(OH) 2 溶液中碱溶出情况。结果表明 :长石在水中碱溶出量比较少 ,溶出的碱主要是钠碱。长石在饱和Ca(OH) 2 溶液中碱溶出量比较多 ,溶出的碱包括钠碱和钾碱。集料碱溶出对混凝土碱含量影响比较小     

硬化水泥浆体孔隙中液相的分离和研究

用压滤法分离了龄期分别为半年和一年的硅酸盐水泥和低碱度水泥硬化浆体孔隙中的液相。溶液中钙的可能存在形态为Ca~(2 )、Ca(OH)~ 和Ca(OH)_2,它们之间的含量比例取决于溶液的OH~-浓度。对玻璃起侵蚀作用的主要为Ca(OH)~ ,而Ca~(2 )和Ca(OH)_2不起明显的侵蚀作用。28d后,中碱玻璃中钠的溶出百分率为抗碱玻璃的3～4倍;而在低碱度水泥浆体中,两种玻璃中钠的溶出量都不大,中碱玻璃中钠在180d内的溶出百分率也只有在硅酸盐水泥浆体中同龄期溶出率的1/12。对硅酸盐水泥浆体孔隙溶液中钙的饱和状况作了进一步的讨论,所得的结论与Diamond的不同,孔隙溶液一直为Ca(OH)_2所饱和,而不是在60～90d后钙从溶液中消失。     

吸附污水钙镁离子及增粘效果

大庆油田某区块采出污水富含高浓度钙镁离子,研究钙镁离子对回注水配制聚合物溶液粘度的影响。利用草炭与NaOH配制腐殖酸钠混合液络合采出污水中的钙镁离子,降低钙镁离子对聚合物溶液粘度的影响,使采出污水达到油田回注粘度标准。研究表明,Ca⁽²⁺⁾、Mg(2+)、Mg⁽²⁺⁾含量在0(2+)含量在0²00mg/L时聚合物溶液粘度严重损失,粘度损失率分别达到最大值63.2%和70.7%;采用腐殖酸钠络合钙镁离子时,腐殖酸钠溶液用量为8.0mL时对钙离子的吸附率达到77.50%,腐殖酸钠混合液用量为6.0mL时对镁离子的吸附率达到83.60%,说明腐殖酸钠对钙、镁离子吸附效果良好。室内实验结果证实了利用腐殖酸钠络合钙镁离子防止聚合物溶液粘度降低的可行性,为现场试验提供参考。     

吸附污水钙镁离子及增粘效果

大庆油田某区块采出污水富含高浓度钙镁离子,研究钙镁离子对回注水配制聚合物溶液粘度的影响。利用草炭与NaOH配制腐殖酸钠混合液络合采出污水中的钙镁离子,降低钙镁离子对聚合物溶液粘度的影响,使采出污水达到油田回注粘度标准。研究表明,Ca~(2+)、Mg~(2+)含量在0~200mg/L时聚合物溶液粘度严重损失,粘度损失率分别达到最大值63.2%和70.7%;采用腐殖酸钠络合钙镁离子时,腐殖酸钠溶液用量为8.0mL时对钙离子的吸附率达到77.50%,腐殖酸钠混合液用量为6.0mL时对镁离子的吸附率达到83.60%,说明腐殖酸钠对钙、镁离子吸附效果良好。室内实验结果证实了利用腐殖酸钠络合钙镁离子防止聚合物溶液粘度降低的可行性,为现场试验提供参考。     

钒渣钠化焙烧熟料浸出液除磷工艺研究

以钒渣钠化焙烧熟料浸出后得到的含钒溶液为原料,分析了二水硫酸钙在碱性条件下对含钒溶液中磷的去除机制,研究了二水硫酸钙用量、溶液pH、反应时间、反应温度等因素对磷去除率、钒损失率以及溶液中五氧化二钒与磷质量浓度比的影响。研究结果表明：在弱碱性条件下,二水硫酸钙可有效去除含钒溶液中的磷,磷去除率达到70%以上、钒损失率小于1%、五氧化二钒与磷质量浓度比大于2 300,满足后续沉钒的要求。确定的除磷工艺条件：二水硫酸钙与磷物质的量比为5.3,溶液pH为9.0,反应时间为30 min,反应温度为25 ℃。除磷后的含钒溶液经沉钒、洗涤、煅烧得到五氧化二钒产品,沉钒率大于99%,五氧化二钒产品质量满足YB/T 5304—2011《五氧化二钒》中99级的要求。     

粉煤灰中SiO_2在不同碱性条件下的溶出量及与火山灰活性指数的关系

采用沸煮法,对Ca(OH)2+NaOH溶液的pH值对粉煤灰的SiO2溶出量的影响进行了研究;同时探讨了粉煤灰的可溶性SiO2量与其火山灰活性指数的关系.结果表明:碱激发溶液的pH值越高,粉煤灰的SiO2溶出量越大;粉煤灰的SiO2溶出量在碱溶液的pH值超过某一特定值后显著增加,表现出较高的活性.采用Ca(OH)2+NaOH混合溶液测定粉煤灰的SiO2溶出量,与实际情况较为吻合.粉煤灰的总SiO2含量越高,SiO2溶出量越高,反之越低;SiO2溶出率与总SiO2含量无关.粉煤灰的可溶性SiO2量和SiO2溶出率与其火山灰活性指数之间没有相关性.     

煤矸石提取氧化铝冷却制度的探讨

煤矸石是煤炭开采过程副产的一种伴生矿,反应活性较低,但是易于活化。因此,煤矸石利用之前必须进行活化,使微粒之间产生剧烈运动来破坏煤矸石稳定状态晶相,提高了煤矸石反应活性。当熟料冷却制度控制不当时,会使大量高活性的硅酸二钙存在,溶出时由于二次反应降低氧化铝溶出率。为了提高氧化铝的溶出率,减少高活性的硅酸二钙含量,用两段冷却保温制度。实验表明,熟料采用自然到1140℃保温15 min,再冷却到550℃保温20 min时,获得熟料氧化铝溶出率高达89.5%。     

钙、镁离子对磷灰石与白云石浮选行为的影响

在碱性条件下,以油酸钠为捕收剂,考察了Ca2+、Mg2+对磷灰石和白云石浮选行为的影响及机理.结果表明,Ca2+的加入使糊精对磷灰石和白云石的抑制作用增强;Mg2+的加入减弱了糊精对磷灰石的抑制,在pH7～10的范围内增强了糊精对白云石的抑制.溶液化学计算分析表明,以羟基化合物形式存在的Ca2+、Mg2+吸附在矿物表面...     

绿僵菌几丁质酶的分离纯化及性质

从自然罹病死亡的金龟子体内分离到一株金龟子绿僵菌（Metarhizium anisopliae）,它在几丁质的诱导下能产生较高活性的几丁质酶.发酵液经硫酸铵盐析、DEAE纤维素柱层析、Phenyl Sepharose^TM 6 Fast Flow疏水柱层析等方法,得到电泳纯的几丁质酶.用SDS-PAGE测得该酶相对分子质量为61.5 kD,而经质谱分析为57.14 kD.最适反应温度为55 ℃,最适反应pH值为6.0,酶的等电点pI为4.02,其N末端序列为VIGPAAPL,用硫酸-酚法测得其含糖量为56.2%.水解几丁质的K_m为14.5 μmol•L^-1.该酶在45 ℃,pH值3.0～9.5较为稳定.Zn²⁺、Ca²⁺、Ba²⁺和Mn²⁺离子对几丁质酶活性有明显的促进作用,而Hg²⁺、Co²⁺和Fe²⁺离子完全抑制几丁质酶的活性.此酶还可被EDTA所抑制,表明金属离子为其活性所必需.PMSF试剂对几丁质酶的活力影响比较大,丝氨酸可能是酶活力的必需基团.     

Formation and Local Structure Analysis of High‐Valence Chromium Ion in Dicalcium Silicate

Dicalcium silicate (2CaO·SiO₂) is a typical silicate compound that exists even at elevated temperatures. Different types of elements can be dispersed in dicalcium silicate to form a solid solution phase. However, the dispersion behavior of transition elements that can display different ionic valences is not well understood. Herein, we investigate the local structure of chromium ions dispersed in dicalcium silicate of different phase states under inert and air atmospheres using Cr K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy and first‐principle calculations. The measured XANES spectra indicated that Cr ions exist as high‐valence states when dispersed in dicalcium silicate in air atmosphere. Specifically, Cr⁶⁺ ions were detected in γ‐dicalcium silicate, which was prepared by annealing a mixture of 2CaO·SiO₂ and Cr₂O₃ at 973 K in air atmosphere. In addition, the XANES spectra obtained via first‐principle calculations revealed that Cr ions, with high‐valence states between Cr⁴⁺ and Cr⁶⁺, in dicalcium silicate, occupy the tetrahedral Si⁴⁺ sites.     

Humic acid fouling in the membrane distillation process

This work investigates the extent of humic acid fouling during the membrane distillation process for water treatment. The effects of pH, ionic strength, and divalent ion on fouling were studied. The experiments were performed with a 0.22-μm PVDF flat-sheet membrane in a direct contact membrane distillation unit. Flux declines were negligible (less than 6%) for the ranges of humic acid concentration, ionic strength, and pH studied. The examination of the membrane surface by SEM revealed a thin deposit layer. The addition of divalent cations (Ca²⁺) into the solution considerably reduced flux when Ca²⁺ concentration exceeded the critical coagulation concentration. Ca²⁺ affected flux by forming complexes with humic acids and resulted in coagulation on the membrane surface. The normalized flux, J/J₀, was 0.57 after 18 h of operation when the CaCl₂ concentration was 3.775 mM. However, the deposit of humic acid coagulate on the membrane surface was loosely packed, and was rather easily removed. Rinsing of the fouled membrane with clean water and a 0.1 M NaOH solution gave 100% of flux recovery.     

Solubility and availability to sugarcane (Saccharum Spp.) of two silicate materials

Silicate materials, dicalcium orthosilicate (Ca₂SiO₄), calcium metasilicate (CaSiO₃), and mini-granulated CaSiO₃, were incorporated into three highly weathered, low-Si soils. The mixtures were moistened to field moisture-holding capacity and incubated in plastic bags for 60 days at approximately 25°C, after which Si was extracted. Application rates of silicate materials were 0, 460, 920, and 1380 mg Si per kg soil. Two ranges of particles sizes, 0.25 to 0.84 mm and 0.074 to 0.15 mm CaSiO₃ and Ca₂SiO₄ were compared. The soils were a Typic Gibbsiorthox, pH 4.6; a Humoxic Tropohumult, pH 4.2; and a Typic Hydrandept, pH 5.0. Materials were evaluated by four extraction procedures: shaking in water, water displacement from saturated soil, shaking in ammonium acetate solution, and biologically by roots of sugarcane (Saccharum Spp. hybrid). Silicate from the CaSiO₃ materials were generally more readily extracted chemically and biologically than silicate from the Ca₂SiO₄. Solubility and availability of Si usually increased as primary particle size of the silicate materials decreased. The exceptions were associated with the most acid (pH 4.2) Ultisol. Mini-granulation did not reduce the effectiveness of CaSiO₃ thus confirming agronomic feasibility of mini-granulation. Plant uptake of Si was most closely related to water-extractable soil Si, followed by Si in saturation extracts and then by NH₄ OAc-extractable Si.Part of a MS thesis submitted to the University of Hawaii by the first author.     

Adsorption of humic acid onto pillared bentonite

Pillared bentonite, a clean and cost-effective adsorbent with high specific areas of 111.3 m²/g and high basalspacing of 1.98 nm, was prepared for the removal of humic acid from water. It is effective for the removal of humic acid with a high adsorption capacity of 537 mg/g, and adsorption is favored under acid conditions. Adsorption is dependent on ionic strength and dissolved NaCl enhanced adsorption. Over 97% removal was observed under natural pH conditions from humic acid solutions containing 10 mg/L Ca²⁺ or Mg²⁺, which suggests that pillared bentonite can be an effective adsorbent for the removal of humic acid for drinking water purification. Pillared bentonite can be regenerated with NaOH, and the regeneration efficiency reaches 83% and 85% when the concentration of NaOH reaches 0.025 and 0.05 mol/L. The mechanism for adsorption of humic acid to pillared bentonite is discussed.     

微乳液的增溶、相态及微乳液/中空纤维膜萃取钕

通过考察非离子型微乳液体系（OP-4+OP-7）/ 苯甲醇/D2EHPA/煤油/盐酸中的混合表面活性剂OP-4［壬基酚聚氧乙烯（4）醚］和OP-7［壬基酚聚氧乙烯（7）醚］配比、盐酸浓度、温度和NaCl对盐酸增溶量的影响以及D2EHPA［二（2-乙基己基）磷酸］和盐酸浓度对体系相态的影响,制备了适合作为液膜分离介质的微乳液体系,同时提出了新的膜萃取过程：微乳液/中空纤维膜萃取,并用于稀土钕的萃取.结果表明,微乳液中盐酸的增溶量随混合表面活性剂HLB值以及盐酸浓度的增大而增大,随温度的升高、NaCl浓度的增大而减小;D2EHPA的加入有利于WinsorⅡ体系的形成;盐酸浓度小于6 mol•dm^-3时也可形成WinsorⅡ体系,而盐酸浓度为7 mol•dm^-3和8 mol•dm^-3时则分别形成WinsorⅢ体系或WinsorⅠ体系;将W/O非离子型微乳液通过中空纤维膜从浓度为300 mg•dm^-3的料液中萃取钕时,采用3个中空纤维膜器串连一次萃取即可使萃取率达95.3%,内相富集倍数18.1.该新膜萃取体系同时具有液膜与固膜萃取的优点,不需进行反萃操作.     

转炉渣中含磷固溶体相的形成行为研究

本工作在1400℃下,将平均尺寸约450 μm的硅酸二钙颗粒加入到CaO-FeO-SiO2-P2O5体系转炉渣,研究了硅酸二钙的溶解及含磷固溶体相的形成行为。结果表明,硅酸二钙颗粒在FeO-SiO2-P2O5体系转炉渣中溶解时,沿硅酸二钙颗粒周围形成3个区域：未熔硅酸二钙区域(边缘区域渗透高FeO含量的液态渣)、液相和固相(2CaO?SiO2固相和2CaO?SiO2-3CaO?P2O5固溶体)共存区域以及基体渣层;转炉渣中含磷固溶体相的形成方式为析出机制和扩散机制共存,通过析出机制形成的固溶体中的磷含量较高、其他元素含量较低;通过扩散机制形成的固溶体中的磷含量相对较低、其他元素含量相对较高。     

Calcium silicate hydrates investigated by solid‐state high resolution H and Si nuclear magnetic resonance

This work focuses on phases formed during cement hydration under high pressure and temperature: portlandite Ca(OH)₂ (CH); hillebrandite Ca₂(SiO₃)(OH)₂ (β‐dicalcium silicate hydrate); calcium silicate hydrate (C-S-H); jaffeite Ca₆(Si₂O₇)(OH)₆ (tricalcium silicate hydrate); α‐C₂SH Ca₂(SiO₃)(OH)₂ (α‐dicalcium silicate hydrate); xonotlite Ca₆(Si₆O₁₇)(OH)₂ and kilchoanite Ca₆(SiO₄)(Si₃O₁₀). Portlandite and hillebrandite were synthesized and characterised by high resolution solid‐state ¹H and ²⁹Si Nuclear Magnetic Resonance. In addition, information from the literature concerning the last five phases was gathered. In certain cases, a schematic 3D‐structure could be determined. These data allow identification of the other phases present in a mixture. Their morphology was also observed by Scanning Electron Microscopy.     

Adsorption of Lead and Cadmium on Ca-Deficient Hydroxyapatite

A Ca-deficient hydroxyapatite(d-HAp) has been used to remove lead and cadmium from their mixed ions solution. The effect of pH, coexistent calcium and magnesium ions, and humic acid on the adsorption efficiency were investigated. The results showed that this d-HAp adsorbed both Cd²⁺ and Pb²⁺ efficiently within a wide pH range. The existence of humic acid reduced the removal efficiency of Cd²⁺ and Pb²⁺. The addition of Ca²⁺ and Mg²⁺ with a concentration of 500 mg/L only slightly reduced the removal efficiency. The adsorption kinetics was described by pseudo-second-order reaction model and the adsorption isotherm followed the Langmuir model.     

邻苯二酚2，3-双加氧酶在恶臭假单胞杆菌整细胞催化中的酶活检测方法

为了定量了解整细胞催化过程中关键酶酶活的变化,以恶臭假单胞菌mt-2为模式菌株,研究其在芳香族化合物降解途径中的关键酶——邻苯二酚2,3-双加氧酶（C23O）的简易检测方法。首先确立了以苯甲酸钠为唯一碳源的培养基,在优化培养条件下,达到了细胞培养和C23O同时诱导表达的目的。进而通过用磷酸缓冲溶液重悬细胞,并用分光光度法监测产物的生成速率（375 nm）,实现在整细胞的条件下,对C23O酶活进行快速准确的测量。在整细胞条件下,C23O的最适温度为35 ℃,最适pH 7.5,而在最适温度和pH下,酶与底物的动力学参数为Km=34.67 μmol•L^-1,Vmax=0.29 μmol•min^-1 •mg干细胞^-1。这些动力学参数与纯酶的相差两到三个数量级。另外通过在细胞悬液中加入0.1 g•L^-1 阳离子表面活性剂（DTAB）作用30 min后,能有效的消除细胞膜的空间障碍,增加细胞膜的通透性,从而使测量的酶活更接近于最大酶活。本研究为整细胞催化及微生物的环境修复过程中酶活的快速检测提出了简易可行的方法。