【作者】 刘畅；

【导师】 陆小华；

【作者基本信息】 南京工业大学 ， 化学工程， 2003， 博士

【摘要】 随着科学技术发展的需要，各种具有特定结构和功能的微米至纳米材料已被材料科学家在实验室里不断研制出来，但都面临着规模化降低成本的问题，而这正是化学工程的强项。然而从化学工程的角度来说，以往它的研究对象主要是流体，过程的控制指标一般为温度、压力以及溶液组成等。若用传统的化工方法能否解决制备这些结构复杂的固相高新技术材料时出现的问题?工艺过程中控制指标将发生什么变化?如何找到宏观控制指标与产品微观结构之间的关系?这些都已成为化学工程研究的前沿课题。 钛基晶须（K₂O·nTiO₂）是一种尺寸在微米级，具有复杂结构的高性能先进材料。要实现钛基晶须规模化制备的关键和难点所在是其水合过程，这是一个复杂的、影响因素繁多的固液离子交换过程，随水合工艺条件的改变，将得到一系列组成、结构和性能各不相同的衍生物如K₂Ti₄O₉、K₂Ti₆O₁₃、K₂Ti₈O₁₇和H₂Ti₄O₉晶须。本课题组以前的工作中，已经发现这种微米级固体的组成和结构与宏观的溶液组成之间存在对应关系，而且固相的组成与结构，可通过控制溶液组成来实现。但固相组成结构与溶液组成之间的这种对应关系能否转变为化工过程的可操作量，以及这种对应关系是否存在现实可操作性，尚未进行研究。 针对上述问题，本文建立了钛基晶须水合过程的热力学和动力学模型，对水合过程进行了定量描述。 对于水合过程的热力学研究，本文从化工角度出发，采用相平衡的概念，将水合过程视为由固相热力学平衡及固液间物料平衡所构成的固液相平衡过程。 在本课题组以前的工作中，已建立了钛基晶须固相热力学平衡模型。但由于缺乏固液相间的物料平衡计算模型，对溶液组成的控制无法转变为化工过程的易控指标。经本文研究发现，固液相间的物料平衡与化工无机盐结晶过程具有相似性，因此，若将本课题组建立的计算无机盐结晶过程的最新成果——固液平衡级算法用于水合过程有望解决这一难题。 本文在严格验证固液平衡级算法的正确性基础上，将其与钛基晶须固相热力学平衡模型结合，建立了完整的水合过程热力学模型，对水合热力学平衡规律进行了完整描述。通过对模型的分析，发现可用化工易控的溶液的pH值和水量来准确控制水合过程，其中溶液的pH值对水合过程的影响更大。初始水合原料中的TiO₂／K₂O摩尔比对最优水合工艺指标影响不大，而滴加盐酸的浓度以0.1M为宜。制备99％的K₂Ti₆O₁₃和K₂Ti₈O₁₇晶须的最优工艺指标为pH=9.3-9.9、水量 摘要为 10mUg和 pH－6石J刀、水量为 10mVg。在上述建立的模型基础上，本文进一步建立了自然浸出条件下的水合热力学模型，计算得到自然浸出制备纯KZTi4Og晶须的条件为 0．ZM的 KOH溶液 10lUg。并建立了 HZTi4Og和 KZTi6O13晶须联产的工艺。 对于水合过程的动力学，本文利用钾离子选择性电极和统计速率理论对其进行了实验测定和理论分析。 通过钾离子选择性电极在线测定了KZSO4晶体的溶解动力学，并用统计速率理论进行关联和解释，表明该实验方法和理论模型可用于表达钾离子在固液界面的传质过程。 钛基晶须水合动力学实验数据和理论分析表明，该过程的控制步骤是固相表面反应过程，酸性溶液中的水合速率比碱性溶液中的要快；减小溶液的pH值和增大初始水量比都可使水合反应速率增加，但pH值的影响比水量比的影响大得多。 pH值是控制钛基晶须团相组成（TIO。／KZO摩尔比）的敏感变量，在 pH值较低的区域水合反应速率远高于 pH值较高区域，因相 TIOZ／KO摩尔比组成变化剧烈；而将溶液pH值控制在水含热力学平衡区域时，因相组成的变化较为平缓，有利于化工过程的控制。因此水合制备KZTi6O13和KZTi8O；，晶须过程中，溶液的pH值应采用经上述热力学计算得出的指标(分别为pH－9．3习．3和pH功石河对人初始水量比则可根据最小废液量和尽量短的水合时间，根据实际需要来选取门—100mUg的范围人这样既可使水合过程能在对时间不敏感，化工易控的区域内进行，又可有效缩短水合时间。 因此，通过对钛基晶须水合热力学和动力学过程的分析表明，为了实现钛基晶须的低成本规模化制备，应将溶液的pH值控制在热力学计算得到的区域，而水量则应根据动力学关系按照操作时间和生产成本来优化选取。 为实现钛基晶须的低成本的快速合成，本文初步研究了微波条件下钛基晶须的合成及其晶须生长机理。通过对微波加热介质、加热时间和起始物料TIOZ／KZO比对产物结构和形貌的分析，表明利用微波固相合成法可快速出各种钛酸钾晶须，微波场下晶须的生长仍符合常规烧结过程的“熔体诱导生长模型”。更多还原

【Abstract】 With the development of science and technology, different nano and micron scale materials with special constructions and functions were developed by scientist, but the biggest problem is how to produce these new materials in large quantity, this make the chemical engineering important. However, from the point of view of chemical engineering, fluid is the main object in previous research and the control variables are temperature, pressure, composition etc. So it is a great challenge for traditional chemical engineering to deal with the new solid materials. This naturally becomes a hot spot in recent chemical engineering researches.Titanium dioxide whisker is a kind of high performance material, which is in micron scale and takes on complex structure. The hydration process is most important part for the large scale preparation of titanium dioxide whisker, generally, it is also most difficult, because it is a complex, multifactor induced solid-liquid ion exchange process. Under different conditions of hydration, different whiskers can be obtained, such as K2Ti4O9, K2Ti6O13, K2Ti8O17 and H2TiO9 In the previous work in our group, it is found that there is a relationship between the consistence and structure of whisker and the consistence of solution, so it is available to control the structure and consistence of the solid by controlling the consistence of the solution. Based on this knowledge, the remaining problem is to find the suitable operation variable in industry process.In this thesis, a thermodynamics model and a kinetics model are established to describe the hydration progress quantitatively.Based on the phase equilibrium theory, the hydration process is regard as a solid-liquid phase equilibrium progress consisting of a solid-phase thermodynamics equilibrium and a mass equilibrium between the solid and liquid phase.The solid-phase thermodynamics equilibrium of titanium dioxide whisker is worked out by previous researchers in our group. However, the operation variable in industry process is hard to find for the lack of the solid-liquid mass balance model. Via the study in this thesis, it is found the solid-liquid equilibrium stage algorithm is a useful tool for this problem.In this thesis, an integrated thermodynamics model for hydration process, which can be used in the description of the process in hydration thermodynamics equilibrium, is established by combing the solid-liquid equilibrium stage algorithm and the model of solid phase thermodynamics equilibrium for titanium dioxide whisker. Based on this model, the pH value and the quantity of water are choused as the control variables and it is also found the influence of pH is bigger. The mole ratio of TiO2/K2O in initial raw materials has not remarkable influence for the product quantity of hydration andthe proper chlorhydraic acid concentration is 0.1M. The optimal condition for 99% K2Ti6O13 and K2Ti8O17 are respectively pH 9.3-9.9, water usage 10ml/g and pH 6.6-7.0, water usage lOml/g. A revised model for hydration thermodynamics under natural leaching-out condition is also given in this thesis. The optimal condition for pure K2Ti4O9 whisker is 10ml/g KOH solution (0.2M). The coupled methodology of H2Ti4O9 whisker and K2Ti6O13 whisker is established in this thesis.Because the online measurement by general spectrophotography is difficult, a new method based on the online measurement of K2SO4 crystal dissolution kinetics by ion selective electrode is established. The statistical velocity theory is also used in this method.The results in this thesis show that, the control step of hydration of titanium dioxide whisker is the surface reaction process in solid phase, the hydration velocity in acid solution is quicker than that in alkaline solution. The reaction velocity increased with the decrease of pH or the increase of initial water usage, but the influence of pH is rather larger.In the preparation of K2Ti6O13 and K2Ti8O17 whiskers, the pH of solution must be calculated by the method above to control the whole hydration progress, a更多还原