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

1.玻璃熔体的伏安研究用示差脉冲伏安法研究了铁、锡、Ce和S离子在钠钙、磷酸盐和无碱玻璃熔体中的氧化还原反应。从电流-电位曲线的峰位计算了半波电势，并讨论了其与温度和熔体组成的关系。结果表明，还原离子的浓度随着温度的升高而增加。对于钠钙熔体中的Fe离子，Fe^&lt；2&gt；/Fe^&lt；3&gt；平衡是由络合生成反应Fe^&lt；3&gt；离子和熔体的碱度决定的。在无碱玻璃熔体中加入Na~+离子的量，并将半波电势外推到Na~+为零浓度时，可以讨论锡离子在无碱玻璃熔体中的平衡。测定了无碱玻璃(MO(M_2O)-SiO_2-Al_2O_3-B_2O_3)、碱或碱土金属氧化物与SiO_2、Al_2O_3、B_2O_3的反应活性。与B_2O_3的反应活性按K_2O&gt；Na_2O&gt；BaO&gt；SrO&gt；CaO&gt；PbO&gt；MgO&gt；ZnO.顺序递增用下列反应的平衡常数K来解释实验结果。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.弄清细化离子氧化还原反应的温度依赖性对澄清细化过程具有重要意义。对于金属离子，在玻璃熔化温度时，[Ox]/[Red]的浓度比应保持一致，预计锡离子适合于无碱玻璃熔体中的细化离子。在硫磺的情况下，硫酸钠的不可逆分解有助于细化过程。

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.