水合氧化铁的制备及其吸附性能研究

采用恒pH沉淀法,以NaOH溶液为沉淀剂,在溶液pH为3~9的范围内制得4种水合氧化铁(即水铁矿,Fh)。通过XRD、表面零电荷时pH(pHPZC)的测定、N2吸附-脱附对其进行了表征。研究了溶液pH对Fh的甲基橙去除率的影响。表征结果显示:4种Fh均为2-线Fh;它们的pHPZC为6.7~7.9;溶液pH为5,7,9时制备的Fh(Fh5,Fh7,Fh9)的N2吸附-脱附曲线均为IUPAC定义的第Ⅲ种类型。实验结果表明:4种Fh均在溶液pH为4时对甲基橙去除率最高;当甲基橙初始质量浓度为30 mg/L时,Fh5对甲基橙的去除率最高,为92.8%。Langmuir方程更适合描述Fh5对甲基橙的吸附行为,甲基橙在Fh5上产生单分子层吸附,该吸附是自发、放热的物理吸附过程。     

集对分析法在尾矿坝稳定性安全评价中的应用

本文运用相关性分析,将与尾矿坝稳定有关的参数和设计指标进行分类,建立了相互独立指标的尾矿坝稳定性评价指标体系,并应用集对理论建立了尾矿坝稳定性评价模型。随后通过国内尾矿库专家系统对体系各指标进行的评估,结合层次分析法,得到了各指标的权重;根据集对分析法,并将指标分成3个级别,由于归一化联系数μ的取值范围[-1,1],按照"均分原则",从而提出尾矿库运行期稳定等级的划分方法。最后,应用尾矿坝稳定性评价模型对某尾矿坝稳定性进行计算分析,实例分析表明,本文建立的尾矿坝稳定性评价指标体系和安全评价模型,可以用于评估尾矿库运行期稳定性的状况。     

Comparison of criteria for prediction of runaway reactions in the sulphuric acid catalyzed esterification of acetic anhydride and methanol

Loss of temperature control is one of the major reasons that can lead to runaway reaction. This occurrence is commonly named thermal runway. The aim of this paper is the application of thermal runaway criteria in order to predict the onset of runaway phenomena and define the range of stability related to operating conditions in the reactor, with specific reference to the esterification of acetic anhydride and methanol catalysed by sulphuric acid tested in isoperibolic conditions. The isoperibolic calorimeter has also been used to obtain thermodynamic, kinetic and physical chemistry data necessary to develop a model for the reaction. Some runaway criteria applied in this work require a model for the process, so a model for the analyzed system been developed.Because of the modest reaction enthalpy and low activation energy this reacting system provide a severe test to the runaway criteria.In this work, various runaway criteria have been applied to the experimental and simulated data and the results obtained have been compared.     

4种硝酸酯热安定性的绝热试验研究

利用绝热加速量热仪(ARC)对硝酸正丙酯(NPN)、硝酸异丙酯(IPN)、太根(TEGDN)、敌根(DEGDN)4种硝酸酯的热稳定性进行了绝热试验研究,得到绝热放热曲线和热分解特征参数。分析了4种物质分解过程的特点,对测试结果进行了修正。计算得到动力学参数和自加速分解温度SADT,以此作为评估热安定性的判据。结果表明,4种硝酸酯在外界热作用下容易发生分解,反应速度较快,伴随明显的热效应和压力效应。4种硝酸酯的热安定性由好到差排序为:IPN、NPN、TEGDN、DEGDN。     

沿空留巷直接顶稳定性突变分析及其控制

保持直接顶稳定,降低其突变所引起的危害是沿空留巷顶板控制的关键。基于沿空留巷直接顶力学模型,采用能量平衡分析法,建立直接顶突变的燕尾突变模型。结合某工程实例,阐述沿空留巷直接顶稳定性突变机理,分析巷帮煤体支撑力、巷内支护阻力、充填体支撑力对直接顶稳定性突变的影响。实践表明,增加工作面超前加固范围,巷内支护采用高预应力强力锚杆与锚索等主动支护,巷旁采用膏体充填,能够提高充填体早期强度,延缓直接顶稳定性突变的发生和减轻突变发生的烈度。     

基于UAHP的采空区稳定性模糊综合评判

为准确评判矿山采空区稳定性等级,通过分析采空区稳定性各影响因素,确定地质、水文、采空区几何参数、环境等4个2级指标为影响其稳定性的主要因素。运用层次分析法(AHP)并结合模糊数学理论,建立采空区稳定性2级模糊综合评判模型。用区间数表示评判结果,分析处理评判矩阵得到专家评判的相似度和差异度,进而获取专家评判的可信度,建立基于不确定型层次分析法(UAHP)的采空区稳定性模糊评判方法。实例计算结果表明:在Ⅰ级评判指标中,地质构造、周围开采影响、地下水活动程度、跨度对采空区稳定性影响较大;用该采空区的稳定性等级为Ⅱ级。用该方法能得出各影响因素的综合权重,准确评判采空区稳定性等级。     

富勒烯甘氨酸铜盐的制备及表征

以富勒烯和甘氨酸为原料合成富勒烯甘氨酸,再与硝酸铜反应得到富勒烯甘氨酸铜盐。通过单因素方法探讨了反应温度、反应时间、反应物物料比对目标物富勒烯甘氨酸铜盐中铜质量分数的影响。获得最佳工艺条件为:富勒烯甘氨酸和硝酸铜的摩尔比1∶5,反应时间2.0 h,反应温度35℃。此时富勒烯甘氨酸铜盐中铜质量分数为17.8%。同时用FT-IR、MS、元素分析及原子吸收等方法表征了产物的结构。用差热仪测试了富勒烯甘氨酸铜盐的热稳定性,表明产物具有良好的热稳定性。     

用有限元强度折减法求解坝坡抗滑稳定安全系数

通过对有限元强度折减法的理论研究,将此法应用到尾矿坝的静力稳定计算中.采用有限元强度折减法和极限平衡法对某尾矿坝进行了坝坡抗滑稳定安全系数的计算,计算结果表明,在应用有限元强度折减法时,采用不同的D-P准则计算出的滑动面基本相同且与传统方法相近,其中D-P3准则计算的安全系数更加接近瑞典圆弧法.因此应用有限元强度折减法求解尾矿坝静力稳定安全系数是可行的,同时说明有限元法可以较好的模拟实际工程中的复杂几何断面形状和材料非线性等问题.     

Potentiometric studies of mixed complexes of cobalt(II) and copper(II) with l‐Asparagine and adenine

A potentiometric titration technique has been used to determine the stability constants for the various complexes of Co(II) and Cu(II) with L‐asparagine and from DNA base, e.g. adenine. Stability constants of ternary systems have been evaluated by the method suggested by Irwing‐Rossotti. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed‐ligand complex formation constants in a determined pH region. Furthermore, the molar fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed‐ligand complexes at 25°C are as follows: log K= 5.25 for Co(II)‐L‐asparagine‐adenine; log K= 9.30 for Cu(II)‐L‐asparagine‐adenine. The ionic strength was kept constant at I = 0.20 with NaClO₄.     

Polarographic investigations on the complexation of cadmium and zinc by thiol peptides

Complex formation of Cd²⁺ and Zn²⁺ with thiol derivatives has been investigated by differential pulse polarography. The binding of Cd²⁺ and Zn²⁺ with cysteine (CySH), glutathione (GSH) and the model peptide N‐acetyl‐cysteine‐methylamide (ASH) reveals different stoichiometry. Thus, Cd²⁺ forms 1:1 and 1:2 complexes with CySH while 1:2 and 1:4 complexes have been observed with GSH and ASH, respectively. Overall formation constants of Cd²⁺ with CySH (Iogβ ₂ 15.3) and with GSH (Iogβ5₂ 14.4) have been estimated using competitive complexation with nitrilotriacetic acid (NTA). Investigation of competition between Zn²⁺ and Cd²⁺ for the thiol complexation has underlined the role played by the amino group in CySH for the stabilization of Zn complexes in contrary to Cd complexes.