新疆柯尔碱膨润土的表征、及其热活化过程和反应动力学研究

发布时间：2019-06-12 08:49

【摘要】：膨润土是以蒙脱石为主要矿物成分的非金属矿,蒙脱石是含水铝硅酸盐层状矿物。膨润土以其优良的物理和化学性能被广泛地应用于工业、农业、医药和科学研究等领域。尽管人们对膨润土已经进行了广泛而深入的研究,但是,由于膨润土具有很强的吸附性、离子交换性和吸湿性,不同产地的膨润土的性质具有较大的差异性。本文以新疆柯尔碱膨润土为研究对象,对其成分、结构、物化性质进行表征,对其所含蒙脱石的热活化过程及其热分解动力学进行了研究。所做工作对理解该种膨润土的物理化学行为具有重要的理论和实际意义。本文首先根据膨润土的化学成分推算出其主要矿物成分蒙脱石的化学结构式为:[(Na,Ca,Mg,K)0.4](Al3+1.58(Fe3+,Fe2+)0.07Mg0.31)Si4O10(OH)2·nH2O。采用比表面积测定仪(BET)、电位测定仪(Zeta电位)、X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、红外光谱仪(FTIR)和热重-差热分析仪(TG-DSC)等测试手段对膨润土原矿进行了结构表征和性质测定。然后,采用综合热分析仪在动态空气气氛条件下,对新疆柯尔碱膨润土的热分解过程进行了研究。研究表明,当热处理温度达到98℃左右时,蒙脱石开始脱去层间水,直至450℃该过程才完全结束;当温度达到500℃左右时,蒙脱石八面体片中的羟基开始脱失,直到750℃该过程完全结束。最后,根据综合热分析数据,采用等转化率法,通过迭代计算获得了准确活化能,再将得到的活化能应用于Malek方法之中,从而推测热分解的反应机理,进一步计算求得指前因子A。结果发现:蒙脱石在98~450℃析出层间水期间,遵循反应模型得的微分和积分表达式分别为:nnf))1(1(-14)(n)(--=ααα,n)-1-1)(Gn=αα)(((式中:α为转化率,反应级数n=1/2),表观活化能为32.81kJ/mol,指前因子lg A的范围为:4.876~4.8821s-。蒙脱石在500~750℃脱去结构羟基水,发生非晶质化,这个过程遵循化学反应模型的微分和积分表达式分别为:f(α)=(1-α)n和G(α)=(1-(1-α)1-n)/(1-n)(式中:α为转化率,反应级数n=2.1),表观活化能为201.85 kJ/mol,指前因子lgA的范围为:11.210~11.2311s-
[Abstract]:Bentonite is a non-metallic mineral with montmorillonite as the main mineral composition. Montmorillonite is a layered mineral of aluminosilicate. Bentonites are widely used in industry, agriculture, medicine and scientific research because of their excellent physical and chemical properties. Although bentonites have been widely and deeply studied, the properties of bentonites from different producing areas are quite different because of their strong adsorption, ion exchange and hygroscopicity. In this paper, the composition, structure and physicochemical properties of Xinjiang Kerr base bentonite were characterized, and the thermal activation process and thermal decomposition kinetics of montmorillonite contained in it were studied. The work done is of great theoretical and practical significance to understand the physical and chemical behavior of the bentonite. In this paper, the chemical structure formula of montmorillonite, which is the main mineral component of bentonite, is calculated according to the chemical composition of bentone. the chemical structure formula of montmorillonite is [(Na,Ca,Mg,K) 0.4] (Al3 1.58 (Fe3, Fe2) 0.07Mg0.31) Si4O10 (OH) 2 路nH2O.. The structure and properties of bentonite raw ore were characterized by specific surface area tester (BET), potentiometer (Zeta potential), X-ray diffractometer (XRD), scanning electron microscope (SEM), infrared spectrometer (FTIR) and thermogravimetric differential thermal analyzer (TG-DSC). Then, the thermal decomposition process of Kal alkali bentonite in Xinjiang was studied by using a comprehensive thermal analyzer under the condition of dynamic air atmosphere. The results show that when the heat treatment temperature reaches about 98 鈩，

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