Open AccessStudying electric double layer under sorption of gold on activated carbons from thiocarbamide solutions
Author(s) -
В. В. Ёлшин,
Ю. Э. Голодков
Publication year - 2021
Publication title -
vestnik irkutskogo gosudarstvennogo tehničeskogo universiteta
Language(s) - English
Resource type - Journals
eISSN - 2500-1590
pISSN - 1814-3520
DOI - 10.21285/1814-3520-2020-6-1337-1346
Subject(s) - sorbent , sorption , adsorption , chemistry , electrochemistry , inorganic chemistry , activated carbon , polarization (electrochemistry) , conductivity , analytical chemistry (journal) , electrode , organic chemistry
The purpose of the article is to research the mechanism of gold-thiocarbamide complex sorption by activated carbons by studying the properties of the resulting electric double layer. The study of the electric double layer of coal sorption surface is conducted using a polar conductometric method based on the simultaneous use of polarization dependences on direct current and conductometric measurements on alternating current. It is shown that the sorption of thiocarbamide complexes of gold occurs more intensively at the cathodic values of sorbent potentials. Dependence of the adsorption value on the potential is actually linear in the negative region from 0.05 to 0.2 V. The absolute value of goldthiocarbamide sorption at the negative sorbent potential of 0.2 V coincides with the maximum values of the polarization current for direct current and conductivity for alternating current. The electrochemical reduction reaction of thiocarbamide compounds results in the formation of neutral thiocarbamide molecules, it might be the reason for gold deposition in a metallic form on the surface of the carbon sorbent. Neutralization of active compounds in the electric double layer creates conditions for the activation of positively charged gold ions directing to the negatively charged sorbent surface. The anodic region of sorbent polarization is characterized by the maximum values of gold ion sorption at the positive potential of 0.2 V. In this case the sorbent surface should be recharged, since in the same region of the potential the maximum AC conductivity is observed. Such conditions should lead to the destruction of the thick part of the electric double layer and, consequently, create favorable sorption conditions. The conducted studies allowed to derive a conclusion that the sor ption of gold-thiocarbamide complexes by activated carbons is significantly influenced by the sorbent potential. The use of the polar conductometric method for studying the electric double layer makes it possible to explain the features of given compound sorption on activated carbons.