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

1. 玻璃熔体的伏安研究应用差分脉冲伏安法研究了铁、锡、铈和S离子在钠石灰、磷酸盐和非碱玻璃熔体中的氧化还原反应。从电流-电位曲线的峰值位置计算半波电位，并讨论了半波电位与温度和熔体成分的关系。可以看出，还原离子的浓度随温度的升高而增加。以钠石灰熔体中的Fe离子为例，发现Fe^<2+>/Fe^<3+>的平衡受Fe^<3+>离子的络合生成反应和熔体碱度的控制。通过在非碱玻璃熔体中加入Na^+离子的量，并将Na^+离子浓度为零时的半波电位外推，可以讨论非碱玻璃熔体中Sn离子的平衡。玻璃光谱——核磁共振研究通过对非碱玻璃（MO(M_2O)-SiO_2-Al_2O_3-B_2O_3）的^<11>B、^<27>Al和^<29>Si核磁共振谱峰分离，测定了碱或碱土氧化物与SiO_2、Al_2O_3和B_2O_3的反应性。与B_2O_3的反应活性依次为K_2O>Na_2O>BaO>SrO>CaO>PbO>MgO>ZnO。用下面反应的平衡常数K来说明实验结果。Si (Q_3) + (Q_3) = Si (Q_4) + B和B (Q_4): K = [Si (Q_4)] [B (Q_4)] / [Si (Q_3)] [B (Q_3) 3。细化离子氧化还原反应的温度依赖性对细化过程的研究具有重要意义。对于金属离子而言，在玻璃熔融温度下，[Ox]/[Red]的浓度比保持一致是重要的，预计Sn离子适合作为非碱玻璃熔体中的细化离子。对于硫，硫酸钠的不可逆分解有助于精炼过程。

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.