A thermodynamic and kinetic study of trace iron removal from aqueous cobalt sulfate solutions using Monophos resin

Abstract

home/jbf high temperature and high pressure conditions and produces iron precipitates, which are difficult to separate from solutions. With solvent extraction, a general problem is emulsification, which causes loss of extractant and contamination of electrolyte. In addition, both chemical precipitation and solvent extraction methods are not able to Abstract Background: High purity cobalt has many important applications, such as magnetic recording media, magnetic recording heads, optoelectronic devices, magnetic sensors, and integrated circuits, etc. To produce 5N or higher purity cobalt in an electro-refining process, one of the challenges is to effectively reduce the Fe content of aqueous cobalt salt solution before electrolysis. This paper describes thermodynamic and kinetic investigations of the Fe adsorption process of a new sulfonated monophosphonic resin with the trade mark Monophos. Methods: Five cobalt sulfate solutions of different Co concentrations were prepared. Fe ions were removed from the solutions by ion exchange method using Monophos resin. Chemical analysis was carried out using a Perkin Elmer ICP-OES. Results: The initial Fe concentrations of about 0.9-2.0 mg/L can be reduced to about 0.3-0.8 mg/L, which is equivalent to an Fe removal rate of 60-67%. The Langmuir isothermal adsorption model applies well to the Fe removal process. A second-order type based on McKay equation fits better with experimental data than other kinetic models. The kinetic curve can be divided into two sections. For t < 30 min, particle diffusion may act as the controlling step, whereas chemical reaction may control the Fe adsorption process in the section t > 30 min. Conclusions: Monophos resin is effective for the removal of trace Fe from cobalt sulfate solution. This ion exchange process obeys the Langmuir isothermal adsorption model and the McKay equation of second-order kinetics.

Kinetic Studies of Wastewater Purification Using Local Sand Samples in Erbil, Kurdistan

“…qm and bL represent Langmuir constants linked with the maximum adsorption capacity (mg/g) and energy of adsorption (L/mg), respectively. A straight line with a slope of 1/qm and intercept 1/qmb should represent a plot of C e /q e versus C e if the adsorption follows the Langmuir equation [16].…”