Extraction of Gold from Alkaline Gold Leaching Solution by Tertiary Amine N235 and Phosphine Oxide
Extraction of gold from alkaline gold leaching solution by N235-TRPO synergistic system was studied. The effects of the concentrations of Tri-akylphosphine oxide(TRPO)and tertiary amine(N235), the initial pH, and the concentration of gold on the extraction of gold and the extraction isotherm were inspected. The ability of extracting other metal elements by this system had been investigated. The effect of alkali concentration on stripping of gold from loaded organic phase had also been studied. The experimental results indicate that the system consisting of 10% N235, 10% TRPO gave high extraction yield for gold along with the lesser extraction of silver and copper which are needed to recover. The gold extraction was over 94%, at pH=9~10 and the stripping of gold from loaded organic phase using 0.05mol/L NaOH can reach91.43%.
Solvent extraction separation of Zn(II), Fe(II), Fe(III) and Cd(II) using tributylphosphate and CYANEX 921 in kerosene from chloride medium
Abstract In this work, the extraction of Zn(II), Fe(II), Fe(III) and Cd(II) with tributylphosphate (TBP) and commercial trioctyl phosphine oxide (CYANEX 921) in kerosene from chloride medium has been studied. Different parameters affecting the extraction of the investigated metal ions such as hydrochloric acid, hydrogen ion, extractant, metal ion concentrations and temperature investigations were carried out. The stoichiometry of the extracted metal species investigated by TBP and CYANEX 921 were found to be HZnCl 3 ·3TBP, HFeCl 4 ·2TBP, H 2 CdCl 4 ·3TBP, HZnCl 3 ·2C921, HFeCl 4 ·C921 and H 2 CdCl 4 ·3C921, respectively. The stripping of the extracted metal species by nitric, sulfuric and hydrochloric acids and distilled water were carried out. Based on the obtained results undiluted TBP was selected as a suitable extractant for the recovery of zinc from pickling solution resulting from hot dipping galvanizing bath.
Electrochemical detection of copper(II) at a gold electrode modified with a self-assembled monolayer of penicillamine
A penicillamine (PCA) self-assembled monolayer (SAM) was prepared on a gold electrode. It has been found that the modified electrode exhibited a selective response to copper ions. As demonstrated by cyclic voltammetric experiments, the SAM-based electrode showed an attractive ability to preconcentrate efficiently traces of copper(II) from solutions. Under optimum conditions, the anodic peak current was proportional to the concentration of Cu(II) in the range from 8.0 × 10−7 to 1.0 × 10−4 M with a detection limit of 4.0 × 10−7 M. Moreover, this modified gold electrode is also characterized by excellent repeatability, showing a relative standard deviation of 3.2% for nine successive measurements of 1.0 × 10−5 M Cu(II). The PCA/Au SAM gold electrode was used for the determination of Cu(II) in a tap water sample and the results showed a good agreement with the data obtained by atomic emission spectrometry.