低温熱水溶液中でのフミン酸および単純有機物による金(III)イオンの還元

抄録

The reduction rate of gold (aq) complexes by humic acid simple organic materials were experimentally determined. The reduction rate of gold (aq) complex by humic acid in the range of 80-120℃ is fast. It's reaction rate constant is in the order of 10^-5s^-1 and the activation energy is 27 ± 3kJ・mol^-1. Comparison of the obtained data with earlier works indicates that the activation energy on the reduction of gold (aq) complexes has a tendency to increase with the increase of the maturity of organic materials (humic acid-lignite-anthracitic coal). Simple organic materials, for example, alcohol and carboxylic acid, were also found to reduce gold (aq) complexes. Ethanol showed one order higher reaction rate constant than acetic acid (ethanol: the order of 10^-5s^-1, acetic acid : the order of 10^-6s^-1). It suggests that the reduction rate depends on functional group of organic material. The reaction rate of gold (aq) complexes by natural organic matters and the activation energy may depend on functional groups and their amounts, the maturity and structure of natural organic matters.