Development of pollution-free fining agent ; mechanism of fining reaction and redox eqilibrium

1.用微分脉冲伏安法研究了钠钙玻璃、磷酸盐玻璃和无碱玻璃熔体中Fe、Sn、Ce和S离子的氧化还原反应。从电流-电位曲线的峰值位置计算了半波电位，并讨论了半波电位与温度和熔体组成的关系。可以看出，还原离子的浓度随着温度的增加而增加。在碱石灰熔体中存在Fe离子的情况下，Fe^<2+>/Fe^<3+>平衡由Fe^<3+>离子与熔体碱度的络合反应决定。Sn离子在无碱玻璃熔体中的平衡可以通过加入熔体中Na^+离子的量，并将半波势外推到Na^+离子浓度为零时的半波势来讨论.玻璃的谱学--核磁共振研究通过对<11><27><29>无碱玻璃（MO（M_2O）-SiO_2-Al_2O_3-B_2O_3）的~（13）B、~（13）Al和~（13）Si核磁共振谱的峰分离，确定了碱金属或碱土金属氧化物与SiO_2、Al_2O_3和B_2O_3的反应活性。与B_2O_3的反应活性依次为K_2O&gt;Na_2O&gt;BaO&gt;SrO&gt;CaO&gt;PbO&gt;MgO&gt;ZnO。下面的反应的平衡常数，K，用于阐明实验结果。Si（Q_3）+B（Q_3）=Si（Q_4）+和B（Q_4）：K=[Si（Q_4）] [B（Q_4）] / [Si（Q_3）] [B（Q_3）]3.澄清离子的氧化还原反应的温度依赖性对于澄清澄清过程是重要的。在金属离子的情况下，[Ox]/[Red]浓度比在玻璃熔化温度下保持一致是很重要的，预计Sn离子适合作为无碱玻璃熔体中的澄清离子。在硫的情况下，硫酸钠的不可逆分解有助于澄清过程。

1. Voltammetric Studies of Glass MeltsThe differential pulse voltammetry was applied to investigate the Redox reaction of Fe, Sn, Ce and S ion in soda lime, phosphate, and non-alkali glass melts. Halfwave potential was computed from the peak position of current-potential curves, and discussed in relation with temperature and melt composition. It was seen that the concentration of reduced ions increases with an increase in temperature. In case of Fe ion in soda lime melt, it turns out that the Fe^<2+>/Fe^<3+> equilibrium is governed by the complex formation reaction Fe^<3+> ion and basicity of the melt. The equilibrium of Sn ion in nonalkali glass melt can be discussed by adding the amount of Na^+ ion in the melts and extrapolating the half wave potential to that of zero concentration of Na^+ ion.2. The Spectroscopy of Glasses -- NMR studyBy peak separation of ^<11>B, ^<27>Al and ^<29>Si NMR spectra of non-alkali glass(MO(M_2O)-SiO_2-Al_2O_3-B_2O_3), reactivity of alkali or alkaline earth oxides with SiO_2, Al_2O_3 and B_2O_3 was determined. The reactivity with B_2O_3 increase in order of K_2O>Na_2O>BaO>SrO>CaO>PbO>MgO>ZnO. The equilibrium constant, K, of the following reaction is applied to elucidate the experimental results. Si(Q_3)+B(Q_3)=Si(Q_4)+and B(Q_4) : K=[Si(Q_4)] [B(Q_4)] / [Si(Q_3)] [B(Q_3)]3. FiningThe temperature dependence of Redox reaction of fining ions is important forclarifyingthe fining process. In the case of metal ion, it was important that [Ox]/[Red] concentration ratio is about unity in glass melting temperature, and it wasexpected that Sn ion is suitable for fining ion in non-alkali glass melts. In case of sulfur, irreversible decomposition of sodium sulphate contributes to fining process.