Batch extraction of cobalt ions in hydrochloric acid solution with a hollow fiber supported liquid membrane in a single colum

Abstract

This research found out the possibility of simultaneously extracting and stripping cobalt from aqueous solutions through a hollow fiber supported liquid membrane (HFSLM) system. Various factors which had effects on this extraction system were also studied including the concentration of cobaltous ions in feed solutions in the range of 5,000 to 10,000 ppm, the pH of feed solutions within the acidic-pH range, the types of strip solution of oxalic acid and hydrochloric acid solutions, the operation modes of circulating and once-through modes, the volumetric flowrates in the range of 100 to 1,000 ml/min, the concentrations of D2EHPA – used as an extractant – in the range of 10 to 25 v/v%, and the types of organic solvent of toluene and n-dodecane. From the experiments, it was found that the oxalic acid could not be employed as a strip solution in this system. However, when the hydrochloric acid was employed as a strip solution, more than 50% of cobaltous ions were extracted and recovered after the third circulation. In comparison with the solvent-extraction batch experiments in which the extraction and the stripping performed separately, the extraction and recovery factors were increased more than four times.