五硼酸钾溶液中含硼物种的研究

Boron-11 Nuclear Magnetic Resonance Study of Aqueous Potassium Pentaborate Solution

中文关键词:  物种分布图  核磁共振  五硼酸钾  硼酸根离子

英文关键词:Formation constant  NMR  Potassium pentaborate  Borate anions

中文摘要:

      采用物种分布图与核磁共振实验研究了五硼酸钾溶液中含硼物种的类型、含量和溶液浓度间关系。研究表明五硼酸钾在稀溶液(0.05 mol/kg(H₂O))中几乎全部水解,主要物种为B(OH)₃和B(OH)-₄；在较浓溶液(0.20 mol/kg(H₂O))中主要物种为B(OH)₃和B₃O₃(OH)-₄,而B₅O₆(OH)-₄和[B₄O₅(OH)2-₄]的含量较小。核磁共振实验研究给出了B(OH)-₄、B₃O₃(OH)-₄和B₅O₆(OH)-₄的生成常数K₁、K₃,、K₅,研究得出B₅O₆(OH)-₄含量很少的原因是其解聚为其它类型硼酸根离子。外加离子促进五硼酸根离子的生成,而高温条件促进B₅O₆(OH)-₄发生解聚反应。

英文摘要:

      The relationship between the type,content and solution concentration of boron-containing species in potassium pentaborate solution was studied using species distribution diagrams and NMR experiments.Studies have shown that potassium pentaborate is almost completely hydrolyzed into B(OH)₃ and B(OH)-₄ in dilute solution(0.05 mol/kg(H₂O)).The main species in the concentrated solution(0.20 mol/kg(H₂O))are B(OH)3 and B₃O₃(OH)-₄,while the content of B₅O₆(OH)-₄ and [B₄O₅(OH)₄2-]is less.The formation constants K₁,K₃ and K₅ of B(OH)-₄,B₃O₃(OH)-₄ and B₅O₆(OH)-₄ were given by NMR experimental study.The reason for the low content of B₅O₆(OH)-₄ is that it depolymerizes into other borate ions.The addition of ions promoted the formation of pentaborate,while high temperature promoted the B₅O₆(OH)-₄ depolymerization.