【作者】 毛善成；

【导师】 高庆宇；

【作者基本信息】 中国矿业大学 ， 矿物加工工程， 2009， 博士

【摘要】 溴酸钠和亚氯酸钠氧化硫化钠的反应,能呈现氢离子自催化、双稳态和持续pH振荡与Pt电位振荡,计算机可以有效模拟氧化过程的复杂动力学行为。有关的原理和方法有可能应用于有硫化钠的无捕收剂浮选的pH控制过程。1.溴酸盐氧化硫化钠在封闭反应器的碱性溶液中,溴酸盐和硫化钠的氧化反应,有一个大幅度的pH（2.5 pH单位）变化和铂电极电位（250 mV）变化,并在开放体系中观察到pH双稳态的存在。在pH大于7的碱性或中性介质中,体系的pH从大约7.9上升到9.3,然后下降到6.5。笔者认为存在两个主要的反应过程:BrO₃^-氧化HS^-/H₂S到零价S（0）,并有H⁺的消耗,是系统pH上升的本质原因,零价S（0）被BrO₃^-进一步氧化为S₂O₃^2-并产生H⁺,这个反应的速率方程可表示为r=k[S₈][BrO₃^-][OH^-]。毛细管电泳测定表明S₂O₃^2-的存在,并为最终产物。作者用3组含有HS^-和S^2-、HS^-和H₂S、H⁺和OH^-的质子和去质子平衡反应以及HS^-/H₂S被BrO₃^-氧化为零价S（0）和S₂O₃^2-的化学反应模型成功地模拟了实验测量的pH动力学曲线。在封闭反应器的酸性溶液中,体系pH从7.8快速下降到7.0,经过一个诱导期平台后再次下降到另一个平台（pH = 5.0）。这样的动力学行为可以用两个氧化过程来表示:BrO₃^-氧化HS^-/H₂S产生零价S（0）,并有H⁺的消耗,是系统pH上升的本质原因,和零价S（0）被BrO₃^-进一步氧化为SO₃^2-并产生H⁺,HSO₃^-被BrO₃^-进一步氧化为SO₄^2-并释放H⁺,是H⁺自催化反应。可用4组含有S^2-和HS^-、HS^-和H₂S、H⁺和OH-、HSO₃^-和SO₃^2-的质子和去质子平衡反应以及HS^-/H₂S被BrO₃^-氧化为零价硫（S8）、HSO₃^-和SO₄^2-的化学反应模型成功地模拟了酸性介质中实验测量的pH动力学和开放体系的pH双稳态行为。2.亚氯酸盐氧化硫化钠在开放体系的亚氯酸盐氧化硫化钠的硫酸介质（pH = 5～6）中,发现了一个持续的pH振荡和氧化还原Pt电位振荡。振荡波的周期约50 min,振荡频率与摄氏温度（℃）成正比关系,振荡反应的动力学行为符合阿仑尼斯关系,测得振荡反应的活化能Ea = 87.3 kJ·mol^-1。H₂S/HS^-被ClO₂^-氧化为零价硫,是消耗H⁺的负反馈过程,S（0）被ClO₂^-/OCl-进一步氧化为S₂O₃^2-,而S₂O₃^2-被进一步氧化为SO₃^2-,形成的HSO₃^-和ClO₂^-反应产生SO₄^2-和H⁺,是和硫价态变化有关的H⁺自催化反应,是主要的H⁺正反馈过程,正、负反馈过程组成一个新的、完全由硫价态变化趋动的pH振荡器。论文建立一个含有S^2-和HS^-, HS^-和H₂S、SO₃^2-和HSO₃^-、OCl-和HOCl、H⁺和HO-的5组质子—去质子平衡反应和9个氧化还原反应组成的非线性动力学模型,来模拟亚氯酸盐氧化硫化钠的pH振荡行为,模型涉及11种物质:HS^-、H₂S、S8、S₂O₃^2-、SO₃^2-、HSO₃^-、OCl-、HOCl、ClO₂^-、H⁺和OH,其中,S₂O₃^2-的存在已被毛细管电泳测定所证实,是一个重要的中间产物,这是H₂O₂氧化S^2-的振荡反应中没有考虑到的中间物。模拟结果和观察到的pH振荡行为完全一致。3.碳酸钙调控系统pH变化的研究石块的颗粒小,对系统pH变化的影响大;搅拌速率高对系统pH变化影响大。该项的研究,对于提高硫化钠在浮选中的利用效率有重要的参考价值。更多还原

【Abstract】 In the thesis, we studied the complex dynamics of the oxidation of sulfide by the bromate and chlorite in aqueous solution in a batch reactor and a continuous - flow stirring tank reactor. The oxidation reactions of sulfide by the bromate and chlorite can exhibit autocatalytic production of pH clock, bistability, and sustained oscillations in pH and redox potential. Computer can simulate the complex dynamics behavior observed during the experiment. Their application of ore flotation has been studied.1. The oxidation of sulfide by the bromate Large-amplitude changes in pH （2.5 pH units） and potential （250 mV） of a platium electrode has been measured during the oxidation of sulfide by bromate ion in in a batch reactor. In basic medium, there is an initial rise in pH followed by a drop. The source of the oscillation in this simple chemical reaction is a two-way oxidation of HS^-/H₂S by the BrO₃^-: a hydrogen ion consumption by oxidation to sulfur （0）, and a hydrogen ion production by oxidation of sulfur （0） to S₂O₃^2-, which is shown here by capillary electrophoresis to be an important final oxidizing product of oxidation of S （ 0 ） by BrO₃^-. A simple reaction scheme, consisting of the protonation equilibria of HS^-and S^2-, HS^- and H₂S, H⁺and OH- , the oxidation of HS^-/H₂S by the BrO₃^- to S （0）, the oxidation of S （0） to S₂O₃^2-（Ⅱ） has successfully been used to simulate the observed dynamical behavior.In acidic medium, there is an initial drop in pH followed by an induction period and by an autocatalytic drop. The source of the oscillation in this simple chemical reaction is a two-way oxidation of HS^-/H₂S by the BrO₃^-: a hydrogen ion consumption by oxidation to sulfur（0）, and a hydrogen ion production by oxidation of sulfur（0） to SO₃^2-, while oxidation of HSO₃^- to SO₄^2- produces H⁺ in an autocatalytic manner. A simple reaction scheme, consisting of the protonation equilibria of HS^-and S^2-, HS^- and H₂S, SO₃^2- and HSO₃^-, H⁺ and OH- , the oxidation of HS^-/H₂S by the BrO₃^- to S （0）, the oxidation of S （0） to SO₃^2-（Ⅳ） , and oxidation of HSO₃^- to SO₄^2- has successfully been used to simulate the observed clock behavior and bistability in acidic medium.2. The oxidation of sulfide by chlorite Sustained oscillations in pH and redox potential are obtained in the chlorite-sulfide system in a continuous-flow stirred tank reactor （CSTR）. The source of the oscillation in this simple chemical reaction is a two-way oxidation of HS^-/H₂S by the ClO₂^-: a hydrogen ion consumption by oxidation to sulfur （0）, and a hydrogen ion production by oxidation of sulfur （0） by OCl-/ClO₂^- to S₂O₃^2-, and oxidation of S₂O₃^2- by ClO₂^- to SO₃^2-（Ⅳ）, while oxidation of HSO₃^- to SO₄^2- produces H⁺ in an autocatalytic manner. A simple reaction scheme, consisting of the protonation equilibria of HS^-and S^2-, HS^- and H₂S, SO₃^2- and HSO₃^-, OCl- and HOCl, H⁺ and OH- , the oxidation of HS^-/H₂S by the ClO₂^- to S₈（0）, the oxidation of S₈（0） to S₂O₃^2-（Ⅳ） , and oxidation of S₂O₃^2-（Ⅳ） by ClO₂^- to SO₃^2- , and oxidation of HSO₃^- to SO₄^2- has successfully been used to simulate the pH oscillatory behavior observed in a CSTR. Temperature is found to have a significant effect on the oscillatory behavior and shows Arrhhenius-like behavior. The value of Ea=87.3 kJ·mol^-1 was obtained for the apparent energy of the oscillations.Autocatalytic oxidation of HSO₃^- by ClO₂^- is the major source of positive feedback of hydrogen ions. The reaction between H₂S and ClO₂^- formation S8, which consumes H⁺, is an important source of negative feedback. A mechanistic model consisting of 5 protonation-deprotonation equilibria and 9 redox reactions is proposed for the oscillatory reaction between S^2- and ClO₂^-. The 11 species included are HS^-, H₂S, S8, S₂O₃^2-, SO₃^2-, HSO₃^-,OCl^-, HOCl, ClO₂^-, H⁺ and OH-. In contrast to the H₂O₂–S^2- oscillation reactions, S₂O₃^2- is shown here by capillary electrophoresis to be an important intermediate. Simulations give excellent qualitative agreement with the pH oscillatory behavior observed in a CSTR .3. pH– Control by Using marble The shape, the periodic time, the region of pH changes can be controlled by using different amounts and grade size of solid granular or lumpy marble. The shape, the periodic time, the region of pH changes can be controlled by using a magnetic stirrer bar with different rpm . The smaller of grade size of solid granular or lumpy marble , the larger of pH changes in region. The larger of the stirring rate, the larger of pH changes in region. Solid granular or lumpy marble used by removal of the H⁺ from the oxidation of sulfide by the bromate ion in the CSTR. A possibility of the new technology of the pH-control has been recognized in ore flotation.更多还原